RE: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Attached slides presented by Manish in the TF-A tech forum.
-----Original Message----- From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Madhukar Pappireddy via TF-A Sent: Tuesday, May 18, 2021 8:59 PM To: Joanna Farley Joanna.Farley@arm.com; Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; tf-a@lists.trustedfirmware.org; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi,
I tried to summarize the discussions in the previous TF-A tech forum regarding the proposal to adopt Hand-off Blocks (HOBs) for passing information along the boot chain. I am certain I could not capture all suggestions/concerns brought up during the call. I apologize if I missed and/or misinterpreted any comments and would appreciate it if everyone could share their thoughts in response to this email thread.
The idea is to share information to other boot phases:
Dynamic information: Created during runtime. Shared in the form of a chain of blobs(built as a linked list of C structure objects i.e., HOB list). Static information: Known at compile time. Historically, shared through the use of Device Tree/ACPI tables
Both the above requirements are common in many ecosystems and need to co-exist.
There are broadly 3 problems to solve: 1. Format of HOB structures: It looks like the consensus is that we could use existing mechanisms for this (BL_AUX_PARAM in TF-A or bloblist in u-boot). 2. Identification of HOB list entries: There is a debate about whether tags would suffice or if the HOB list producer and consumer would depend on UUID/GUIDs for identifying a specific HOB structure. Another suggestion was to use a hybrid approach. Reserve a single tag ID for identifying/constructing a HOB structure that further leverages UUID based identifier. This way, the generic HOB list doesn't need to support UUIDs and can work with tags. 3. The design contract for the static interface between two boot phases: The problem at hand is whether to pass a pointer to a HOB list or a device tree blob through the general-purpose registers for configuration hand-off between two boot phases. Some proposals that came up: > Proposal 1: Always pass a pointer to the device tree blob through the GP register and capture the pointer to the HOB list as a property of a node that is uniquely identifiable by the downstream boot phase. This needs to define a device tree binding such that producer and consumer agree on the information passed. > Proposal 2: Pass a pointer to a generic container through the GP register that can be interpreted appropriately by both boot loaders(i.e., producer and consumer of the boot info). This container can either be a dtb or a HOB list which can be simply inferred by checking for a magic header that indicates if the buffer appears to be a flattened device tree. > One another concern that was brought up offline is to make sure we don't break current design contracts between various boot loader phases in TF-A. Many of the general-purpose registers have a designated purpose such as to share configurations between BL images( such as firmware config dtb, SoC config dtb, Non trusted firmware config dtb, memory layout, entry point info, etc.).
If I am not mistaken, a single design may not fit the needs of every segment(client, Infra, embedded) and the forum is open to solutions tailored for individual segments. Joanna will be sending a follow up email with more information about future TF-A tech forums that serves as a platform for further discussions.
Thanks, Madhukar
-----Original Message----- From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Joanna Farley via TF-A Sent: Sunday, May 16, 2021 5:19 AM To: Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Apologies I failed with the recording. Manish/Madhu will reply early next week with the slides and some notes to help with a follow up session which we hope to hold this Thursday. Invite and agenda will also be sent out early next week.
Thanks
Joanna
On 14/05/2021, 13:30, "TF-A on behalf of Okash Khawaja via TF-A" <tf-a-bounces@lists.trustedfirmware.org on behalf of tf-a@lists.trustedfirmware.org> wrote:
Hi,
Do we have slides and video from last week's discussion?
Thanks, Okash
On Wed, May 5, 2021 at 11:52 PM Simon Glass via TF-A tf-a@lists.trustedfirmware.org wrote: > > Hi Harb, > > Thanks for the idea. I am still not completely sure what benefit UUID provides to an open project. I'd like to propose something different, more in the spirit of open collaboration. I also worry that the word 'standard' seems to be a synonym for UUIDs, UEFI, etc., i.e. enabling/preferring closed-source firmware and the continued decline of open-source projects. It really should not be. > > So I suggest: Use simple integer IDs and reserve some area for 'private' use. If you want to collaborate across projects outside your company, you either need to allocate a 'public' ID or agree privately between the parties which private ID to use. > > This means that the default and easiest option is for collaboration and a public ID, with private ones (whose purpose may be secret) reserved just for private use. > > Regards, > Simon > > On Wed, 5 May 2021 at 11:42, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote: >> >> Hey Folks, >> >> We wanted to put out a middle-ground proposal to help guide the discussion on the call tomorrow. >> >> >> >> A proposal that we have been discussing offline involves reserving a single tag ID for the purpose of construction UEFI PI HOB List structure, and that tag would be used to identify a HOB-specific structure that does leverage UUID based identifier. This will eliminate the burden of having to support UUID as the tag, and this enables projects that require UUID based identifiers for the broad range of HOB structures that need to be produced during the booting of the platform. Once we have a tag for a HOB list, this will enable various HOB producers that can add/extend the HOB list in TF-A code (or even pre-TF-A code), with a HOB consumer for that UUID/GUID on the other side (i.e. whatever the BL33 image is booting on that platform). >> >> >> >> Essentially, the idea is if someone would like to support HOB structures in a standard way using TF-A, they would wrap it up in a BL_AUX_PARAM/BLOB structure (whatever the group decides) and the way we identify the structure as a HOB list is with this new reserved tag. >> >> >> >> Hopefully that makes sense and less contentious. Look forward to discuss this further on the call. >> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: Manish Pandey2 Manish.Pandey2@arm.com >> Sent: Friday, April 30, 2021 8:14 AM >> To: François Ozog francois.ozog@linaro.org >> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> Hi All, >> >> >> >> Please find invite for next TF-A Tech Forum session to continue our discussions on HOB implementation, feel free to forward it to others. >> >> >> >> The next TF-A Tech Forum is scheduled for Thu 6th May 2021 16:00 – 17:00 (BST). >> >> >> >> Agenda: >> >> Discussion Session: Static and Dynamic Information Handling in TF-A >> >> Lead by Manish Pandey and Madhukar Pappireddy >> >> · There is ongoing mailing lists discussion[1] related with adopting a mechanism to pass information through boot stages. >> >> The requirement is two-fold: >> >> 1. Passing static information(config files) >> >> 2. Passing dynamic information (Hob list) >> >> In the upcoming TF-A tech forum, we can start with a discussion on dynamic information passing and if time permits, we can cover static information passing. The purpose of the call is to have an open discussion and continue the discussion from the trusted-substrate call[2] done earlier. We would like to understand the various requirements and possible ways to implement it in TF-A in a generalized way so that it can work with other Firmware projects. >> >> >> >> The two specific item which we would like to discuss are: >> >> 1. HOB format: TF-A/u-boot both has an existing bloblist implementation, which uses tag values. Question, can this be enhanced to use hybrid values(Tag and UUID) both? >> >> 2. Standardization on Physical register use to pass base of HoB data structure. >> >> References: >> >> [1] https://lists.trustedfirmware.org/pipermail/tf-a/2021-April/001069.html >> >> [2] https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q% >> >> >> >> Thanks >> >> >> >> Joanna >> >> >> >> You have been invited to the following event. >> >> TF-A Tech Forum >> >> When >> >> Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time >> >> Calendar >> >> tf-a@lists.trustedfirmware.org >> >> Who >> >> • >> >> Bill Fletcher- creator >> >> • >> >> tf-a@lists.trustedfirmware.org >> >> more details » >> >> >> >> We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC. >> >> >> >> Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/ >> >> >> >> Trusted Firmware is inviting you to a scheduled Zoom meeting. >> >> >> >> Join Zoom Meeting >> >> https://zoom.us/j/9159704974 >> >> >> >> Meeting ID: 915 970 4974 >> >> >> >> One tap mobile >> >> +16465588656,,9159704974# US (New York) >> >> +16699009128,,9159704974# US (San Jose) >> >> >> >> Dial by your location >> >> +1 646 558 8656 US (New York) >> >> +1 669 900 9128 US (San Jose) >> >> 877 853 5247 US Toll-free >> >> 888 788 0099 US Toll-free >> >> Meeting ID: 915 970 4974 >> >> Find your local number: https://zoom.us/u/ad27hc6t7h >> >> >> >> ________________________________ >> >> From: François Ozog francois.ozog@linaro.org >> Sent: 08 April 2021 16:50 >> To: Manish Pandey2 Manish.Pandey2@arm.com >> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> Hi >> >> >> >> here is the meeting recording: >> >> https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%z >> >> >> >> I am really sorry about the confusion related to the meeting time. I have now understood: the Collaborate portal uses a specific calendar which is tied to US/Chicago timezone while the actual Google Calendar is tied to Central Europe timezone. I am going to drop the Collaborate portal and use a shared Google calendar (it should be visible on the trusted-substrate.org page). >> >> >> >> I'll try to summarize what I learnt and highlight my view on what can be next steps in a future mail. >> >> >> >> Cheers >> >> >> >> FF >> >> >> >> On Thu, 8 Apr 2021 at 13:56, Manish Pandey2 via TF-A tf-a@lists.trustedfirmware.org wrote: >> >> Hi, >> >> >> >> From TF-A project point of view, we prefer to use existing mechanism to pass parameters across boot stages using linked list of tagged elements (as suggested by Julius). It has support for both generic and SiP-specific tags. Having said that, it does not stop partners to introduce new mechanisms suitable for their usecase in platform port initially and later move to generic code if its suitable for other platforms. >> >> >> >> To start with, Ampere can introduce a platform specific implementation of memory tag(speed/NUMA topology etc) which can be evaluated and discussed for generalization in future. The tag will be populated in BL2 stage and can be forwarded to further stages(and to BL33) by passing the head of list pointer in one of the registers. Initially any register can be used but going forward a standardization will be needed. >> >> >> >> The U-boot bloblist mentioned by Simon is conceptually similar to what TF-A is using, if there is consensus of using bloblist/taglist then TF-A tag list may be enhanced to take best of both the implementations. >> >> >> >> One of the potential problems of having structure used in different projects is maintainability, this can be avoided by having a single copy of these structures in TF-A (kept inside "include/export" which intended to be used by other projects.) >> >> >> >> Regarding usage of either UUID or tag, I echo the sentiments of Simon and Julius to keep it simple and use tag values. >> >> >> >> Looking forward to having further discussions on zoom call today. >> >> >> >> Thanks >> >> Manish P >> >> >> >> ________________________________ >> >> From: TF-A tf-a-bounces@lists.trustedfirmware.org on behalf of Julius Werner via TF-A tf-a@lists.trustedfirmware.org >> Sent: 25 March 2021 02:43 >> To: Simon Glass sjg@chromium.org >> Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> Just want to point out that TF-A currently already supports a (very simple) mechanism like this: >> >> >> >> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+... >> >> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+... >> >> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+... >> >> >> >> It's just a linked list of tagged elements. The tag space is split into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31. >> >> >> >> I would echo Simon's sentiment of keeping this as simple as possible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once. >> >> >> >> On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A tf-a@lists.trustedfirmware.org wrote: >> >> Hi Harb, >> >> >> >> On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote: >> >> Hello Folks, >> >> Appreciate the feedback and replies on this. Glad to see that there is interest in this topic. >> >> >> >> I try to address the comments/feedback from Francois and Simon below…. >> >> >> >> @François Ozog – happy to discuss this on a zoom call. I will make that time slot work, and will be available to attend April 8, 4pm CT. >> >> >> >> Note that I’m using the term “HOB” here more generically, as there are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases. >> >> >> >> The whole point here is to provide mechanism to develop firmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM). >> >> >> >> Keep in mind, in the server/datacenter market segment we are not building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model: >> >> “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2, BL31, and *possibly* one or more BL32 instances >> “Platform” or “board” firmware – in TF-A this may map to BL33 and *possibly* one or more BL32 instances. >> >> >> >> Even the platform firmware stack could be further fragmented by having multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code. >> >> >> >> To support a broad range of platform designs with a broad range of memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software. >> >> >> >> I understand the versatility of DT, but I see two major problems with DT: >> >> DT requires more complicated parsing to get properties, and even more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained. >> DT is probably overkill for this purpose – We really just want a list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob) >> >> >> >> I think that we should not mix the efforts around DT/ACPI specs with what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs). >> >> >> >> Frankly, I would personally push back pretty hard on defining SMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls. >> >> >> >> Please do let me know if you disagree and why. Look forward to discussing on this thread or on the call. >> >> >> >> @Simon Glass - Thanks for the pointer to bloblist. I briefly reviewed and it seems like a good baseline for what we may be looking for. >> >> >> >> That being said, I would say that there is some benefit in having some kind of unique identifiers (e.g. UUID or some unique signature) so that we can tie standardized data structures (based on some future TBD specs) to a particular ID. For example, if the TPM driver in BL33 is looking for the TPM structure in the HOB/BOB list, and may not care about the other data blobs. The driver needs a way to identify and locate the blob it cares about. >> >> >> >> The tag is intended to serve that purpose, although perhaps it should switch from an auto-allocating enum to one with explicit values for each entry and a range for 'local' use. >> >> >> >> I guess we can achieve this with the tag, but the problem with tag when you have eco-system with a lot of parties doing parallel development, you can end up with tag collisions and folks fighting about who has rights to what tag values. We would need some official process for folks to register tags for whatever new structures we define, or maybe some tag range for vendor specific structures. This comes with a lot of pain and bureaucracy. On the other hand, UUID has been a proven way to make it easy to just define your own blobs with *either* standard or vendor specific structures without worry of ID collisions between vendors. >> >> >> >> True. I think the pain is overstated, though. In this case I think we actually want something that can be shared between projects and orgs, so some amount of coordination could be considered a benefit. It could just be a github pull request. I find the UUID unfriendly and not just to code size and eyesight! Trying to discover what GUIDs mean or are valid is quite tricky. E.g. see this code: >> >> >> >> #define FSP_HOB_RESOURCE_OWNER_TSEG_GUID \ >> EFI_GUID(0xd038747c, 0xd00c, 0x4980, \ >> 0xb3, 0x19, 0x49, 0x01, 0x99, 0xa4, 0x7d, 0x55) >> >> (etc.) >> >> >> >> static struct guid_name { >> efi_guid_t guid; >> const char *name; >> } guid_name[] = { >> { FSP_HOB_RESOURCE_OWNER_TSEG_GUID, "TSEG" }, >> { FSP_HOB_RESOURCE_OWNER_FSP_GUID, "FSP" }, >> { FSP_HOB_RESOURCE_OWNER_SMM_PEI_SMRAM_GUID, "SMM PEI SMRAM" }, >> { FSP_NON_VOLATILE_STORAGE_HOB_GUID, "NVS" }, >> { FSP_VARIABLE_NV_DATA_HOB_GUID, "Variable NVS" }, >> { FSP_GRAPHICS_INFO_HOB_GUID, "Graphics info" }, >> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID1, "PCD database ea" }, >> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID2, "PCD database 9b" }, >> >> (never figured out what those two are) >> >> >> { FSP_HOB_RESOURCE_OWNER_PEIM_DXE_GUID, "PEIM Init DXE" }, >> { FSP_HOB_RESOURCE_OWNER_ALLOC_STACK_GUID, "Alloc stack" }, >> { FSP_HOB_RESOURCE_OWNER_SMBIOS_MEMORY_GUID, "SMBIOS memory" }, >> { {}, "zero-guid" }, >> {} >> }; >> >> static const char *guid_to_name(const efi_guid_t *guid) >> { >> struct guid_name *entry; >> >> for (entry = guid_name; entry->name; entry++) { >> if (!guidcmp(guid, &entry->guid)) >> return entry->name; >> } >> >> return NULL; >> } >> >> >> >> Believe it or not it took a fair bit of effort to find just that small list, with nearly every one in a separate doc, from memory. >> >> >> >> >> >> We can probably debate whether there is any value in GUID/UUID or not during the call… but again, boblist seems like a reasonable starting point as an alternative to HOB. >> >> >> >> Indeed. There is certainly value in both approaches. >> >> >> >> Regards, >> >> Simon >> >> >> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: François Ozog francois.ozog@linaro.org >> Sent: Tuesday, March 23, 2021 10:00 AM >> To: François Ozog francois.ozog@linaro.org; Ron Minnich rminnich@google.com; Paul Isaac's paul.isaacs@linaro.org >> Cc: Simon Glass sjg@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> +Ron Minnich +Paul Isaac's >> >> >> >> Adding Ron and Paul because I think this interface should be also benefiting LinuxBoot efforts. >> >> >> >> On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A tf-a@lists.trustedfirmware.org wrote: >> >> Hi, >> >> >> >> I propose we cover the topic at the next Trusted Substrate zoom call on April 8th 4pm CET. >> >> >> >> The agenda: >> >> ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, S-EL2, SCP) to adapt hardware description to some runtime conditions. >> >> runtime conditions here relates to DRAM size and topology detection, secure DRAM memory carvings, PSCI and SCMI interface publishing. >> >> >> >> For additional background on existing metadata: UEFI Platform Initialization Specification Version 1.7, 5.5 Resource Descriptor HOB >> >> Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY. >> >> This HOB lacks memory NUMA attachment or something that could be related to fill SRAT table for ACPI or relevant DT proximity domains. >> >> HOB is not consistent accros platforms: some platforms (Arm) lists memory from the booting NUMA node, other platforms (x86) lists all memory from all NUMA nodes. (At least this is the case on the two platforms I tested). >> >> >> >> There are two proposals to use memory structures from SPL/BLx up to the handover function (as defined in the Device Tree technical report) which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or EDK2. >> >> I would propose we also discuss possibility of FF-A interface to actually query information or request actions to be done (this is a model actually used in some SoCs with proprietary SMC calls). >> >> >> >> Requirements (to be validated): >> >> - ACPI and DT hardware descriptions. >> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2) >> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, TF-A/LinuxBoot) >> >> - at least allows complete DRAM description and "persistent" usage (reserved areas for secure world or other usages) >> >> - support secure world device assignment >> >> >> >> Cheers >> >> >> >> FF >> >> >> >> >> >> On Mon, 22 Mar 2021 at 19:56, Simon Glass sjg@chromium.org wrote: >> >> Hi, >> >> Can I suggest using bloblist for this instead? It is lightweight, >> easier to parse, doesn't have GUIDs and is already used within U-Boot >> for passing info between SPL/U-Boot, etc. >> >> Docs here: https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist >> Header file describes the format: >> https://github.com/u-boot/u-boot/blob/master/include/bloblist.h >> >> Full set of unit tests: >> https://github.com/u-boot/u-boot/blob/master/test/bloblist.c >> >> Regards, >> Simon >> >> On Mon, 22 Mar 2021 at 23:58, François Ozog francois.ozog@linaro.org wrote: >> > >> > +Boot Architecture Mailman List boot-architecture@lists.linaro.org >> > >> > standardization is very much welcomed here and need to accommodate a very >> > diverse set of situations. >> > For example, TEE OS may need to pass memory reservations to BL33 or >> > "capture" a device for the secure world. >> > >> > I have observed a number of architectures: >> > 1) pass information from BLx to BLy in the form of a specific object >> > 2) BLx called by BLy by a platform specific SMC to get information >> > 3) BLx called by BLy by a platform specific SMC to perform Device Tree >> > fixups >> > >> > I also imagined a standardized "broadcast" FF-A call so that any firmware >> > element can either provide information or "do something". >> > >> > My understanding of your proposal is about standardizing on architecture 1) >> > with the HOB format. >> > >> > The advantage of the HOB is simplicity but it may be difficult to implement >> > schemes such as pruning a DT because device assignment in the secure world. >> > >> > In any case, it looks feasible to have TF-A and OP-TEE complement the list >> > of HOBs to pass information downstream (the bootflow). >> > >> > It would be good to start with building the comprehensive list of >> > information that need to be conveyed between firmware elements: >> > >> > information. | authoritative entity | reporting entity | information >> > exchanged: >> > dram | TFA | TFA | >> > <format to be detailed, NUMA topology to build the SRAT table or DT >> > equivalent?> >> > PSCI | SCP | TFA? | >> > SCMI | SCP or TEE-OS | TFA? TEE-OS?| >> > secure SRAM | TFA. | TFA. | >> > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | >> > other? | | >> > | >> > >> > Cheers >> > >> > FF >> > >> > >> > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < >> > tf-a@lists.trustedfirmware.org> wrote: >> > >> > > Hello Folks, >> > > >> > > >> > > >> > > I'm emailing to start an open discussion about the adoption of a concept >> > > known as "hand-off blocks" or HOB to become a part of the TF-A Firmware >> > > Framework Architecture (FFA). This is something that is a pretty major >> > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s >> > > designed to enable a broad range of highly configurable datacenter >> > > platforms. >> > > >> > > >> > > >> > > >> > > >> > > What is a HOB (Background)? >> > > >> > > --------------------------- >> > > >> > > UEFI PI spec describes a particular definition for how HOB may be used for >> > > transitioning between the PEI and DXE boot phases, which is a good >> > > reference point for this discussion, but not necessarily the exact solution >> > > appropriate for TF-A. >> > > >> > > >> > > >> > > A HOB is simply a dynamically generated data structure passed in between >> > > two boot phases. This is information that was obtained through discovery >> > > and needs to be passed forward to the next boot phase *once*, with no API >> > > needed to call back (e.g. no call back into previous firmware phase is >> > > needed to fetch this information at run-time - it is simply passed one time >> > > during boot). >> > > >> > > >> > > >> > > There may be one or more HOBs passed in between boot phases. If there are >> > > more than one HOB that needs to be passed, this can be in a form of a "HOB >> > > table", which (for example) could be a UUID indexed array of pointers to >> > > HOB structures, used to locate a HOB of interest (based on UUID). In such >> > > cases, instead of passing a single HOB, the boot phases may rely on passing >> > > the pointer to the HOB table. >> > > >> > > >> > > >> > > This has been extremely useful concept to employ on highly configurable >> > > systems that must rely on flexible discovery mechanisms to initialize and >> > > boot the system. This is especially helpful when you have multiple >> > > >> > > >> > > >> > > >> > > >> > > Why do we need HOBs in TF-A?: >> > > >> > > ----------------------------- >> > > >> > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server SoC in >> > > a way that is SoC specific *but* platform agnostic. This means that a >> > > single ARM SoC that a SiP may deliver to customers may provide a single >> > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a broad >> > > range of platform designs and configurations in order to boot a platform >> > > specific firmware (e.g. BL33 and possibly even BL32 code). In order to >> > > achieve this, the platform configuration must be *discovered* instead of >> > > statically compiled as it is today in TF-A via device tree based >> > > enumeration. The mechanisms of discovery may differ broadly depending on >> > > the relevant industry standard, or in some cases may have rely on SiP >> > > specific discovery flows. >> > > >> > > >> > > >> > > For example: On server systems that support a broad range DIMM memory >> > > population/topologies, all the necessary information required to boot is >> > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over an >> > > I2C bus. Leveraging the SPD bus, may platform variants could be supported >> > > with a single TF-A binary. Not only is this information required to >> > > initialize memory in early boot phases (e.g. BL2), the subsequent boot >> > > phases will also need this SPD info to construct a system physical address >> > > map and properly initialize the MMU based on the memory present, and where >> > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) may >> > > need to generate standard firmware tables to the operating systems, such as >> > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. SLIT, >> > > SRAT, even NFIT if NVDIMM's are present). >> > > >> > > >> > > >> > > In short, it all starts with a standardized or vendor specific discovery >> > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of >> > > information to the next boot stages (e.g. BL31/BL32/BL33). >> > > >> > > >> > > >> > > Today, every HOB may be a vendor specific structure, but in the future >> > > there may be benefit of defining standard HOBs. This may be useful for >> > > memory discovery, passing the system physical address map, enabling TPM >> > > measured boot, and potentially many other common HOB use-cases. >> > > >> > > >> > > >> > > It would be extremely beneficial to the datacenter market segment if the >> > > TF-A community would adopt this concept of information passing between all >> > > boot phases as opposed to rely solely on device tree enumeration. This is >> > > not intended to replace device tree, rather intended as an alternative way >> > > to describe the info that must be discovered and dynamically generated. >> > > >> > > >> > > >> > > >> > > >> > > Conclusion: >> > > >> > > ----------- >> > > >> > > We are proposing that the TF-A community begin pursuing the adoption of >> > > HOBs as a mechanism used for information exchange between each boot stage >> > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term we >> > > want to explore standardizing some HOB structures for the BL33 phase (e.g. >> > > UEFI HOB structures), but initially would like to agree on this being a >> > > useful mechanism used to pass information between each boot stage. >> > > >> > > >> > > >> > > Thanks, >> > > >> > > --Harb >> > > >> > > >> > > >> > > >> > > >> > > >> > > -- >> > > TF-A mailing list >> > > TF-A@lists.trustedfirmware.org >> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> > > >> > >> > >> > -- >> > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* >> > T: +33.67221.6485 >> > francois.ozog@linaro.org | Skype: ffozog >> > _______________________________________________ >> > boot-architecture mailing list >> > boot-architecture@lists.linaro.org >> > https://lists.linaro.org/mailman/listinfo/boot-architecture >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group >> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group >> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group >> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> > > -- > TF-A mailing list > TF-A@lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a
-- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.
It’s a bit short notice to host another TF-A Tech-forum call on this tomorrow for a live debate as well as Manish who led the call last time is not available this week. So I propose our next TF-A Techforum session on Thursday 3rd June at 4pm BST and between now and then email discussions can possibly be pursued.
From a TF-A perspective we want to help facilitate a number of segments/use-cases we heard about as Madhu mentions below. As such any enablement we can provide in TF-A common code would be good to identify that contributors to other segments/use-cases can build upon in shared platform code in TF-A or elsewhere outside the TF-A repository of that works better for those segments/use-cases.
Thanks
Joanna
On 19/05/2021, 03:50, "Madhukar Pappireddy" Madhukar.Pappireddy@arm.com wrote:
Attached slides presented by Manish in the TF-A tech forum.
-----Original Message----- From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Madhukar Pappireddy via TF-A Sent: Tuesday, May 18, 2021 8:59 PM To: Joanna Farley Joanna.Farley@arm.com; Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; tf-a@lists.trustedfirmware.org; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi,
I tried to summarize the discussions in the previous TF-A tech forum regarding the proposal to adopt Hand-off Blocks (HOBs) for passing information along the boot chain. I am certain I could not capture all suggestions/concerns brought up during the call. I apologize if I missed and/or misinterpreted any comments and would appreciate it if everyone could share their thoughts in response to this email thread.
The idea is to share information to other boot phases: > Dynamic information: Created during runtime. Shared in the form of a chain of blobs(built as a linked list of C structure objects i.e., HOB list). > Static information: Known at compile time. Historically, shared through the use of Device Tree/ACPI tables
Both the above requirements are common in many ecosystems and need to co-exist.
There are broadly 3 problems to solve: 1. Format of HOB structures: It looks like the consensus is that we could use existing mechanisms for this (BL_AUX_PARAM in TF-A or bloblist in u-boot). 2. Identification of HOB list entries: There is a debate about whether tags would suffice or if the HOB list producer and consumer would depend on UUID/GUIDs for identifying a specific HOB structure. Another suggestion was to use a hybrid approach. Reserve a single tag ID for identifying/constructing a HOB structure that further leverages UUID based identifier. This way, the generic HOB list doesn't need to support UUIDs and can work with tags. 3. The design contract for the static interface between two boot phases: The problem at hand is whether to pass a pointer to a HOB list or a device tree blob through the general-purpose registers for configuration hand-off between two boot phases. Some proposals that came up: > Proposal 1: Always pass a pointer to the device tree blob through the GP register and capture the pointer to the HOB list as a property of a node that is uniquely identifiable by the downstream boot phase. This needs to define a device tree binding such that producer and consumer agree on the information passed. > Proposal 2: Pass a pointer to a generic container through the GP register that can be interpreted appropriately by both boot loaders(i.e., producer and consumer of the boot info). This container can either be a dtb or a HOB list which can be simply inferred by checking for a magic header that indicates if the buffer appears to be a flattened device tree. > One another concern that was brought up offline is to make sure we don't break current design contracts between various boot loader phases in TF-A. Many of the general-purpose registers have a designated purpose such as to share configurations between BL images( such as firmware config dtb, SoC config dtb, Non trusted firmware config dtb, memory layout, entry point info, etc.).
If I am not mistaken, a single design may not fit the needs of every segment(client, Infra, embedded) and the forum is open to solutions tailored for individual segments. Joanna will be sending a follow up email with more information about future TF-A tech forums that serves as a platform for further discussions.
Thanks, Madhukar
-----Original Message----- From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Joanna Farley via TF-A Sent: Sunday, May 16, 2021 5:19 AM To: Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Apologies I failed with the recording. Manish/Madhu will reply early next week with the slides and some notes to help with a follow up session which we hope to hold this Thursday. Invite and agenda will also be sent out early next week.
Thanks
Joanna
On 14/05/2021, 13:30, "TF-A on behalf of Okash Khawaja via TF-A" <tf-a-bounces@lists.trustedfirmware.org on behalf of tf-a@lists.trustedfirmware.org> wrote:
Hi,
Do we have slides and video from last week's discussion?
Thanks, Okash
On Wed, May 5, 2021 at 11:52 PM Simon Glass via TF-A tf-a@lists.trustedfirmware.org wrote: > > Hi Harb, > > Thanks for the idea. I am still not completely sure what benefit UUID provides to an open project. I'd like to propose something different, more in the spirit of open collaboration. I also worry that the word 'standard' seems to be a synonym for UUIDs, UEFI, etc., i.e. enabling/preferring closed-source firmware and the continued decline of open-source projects. It really should not be. > > So I suggest: Use simple integer IDs and reserve some area for 'private' use. If you want to collaborate across projects outside your company, you either need to allocate a 'public' ID or agree privately between the parties which private ID to use. > > This means that the default and easiest option is for collaboration and a public ID, with private ones (whose purpose may be secret) reserved just for private use. > > Regards, > Simon > > On Wed, 5 May 2021 at 11:42, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote: >> >> Hey Folks, >> >> We wanted to put out a middle-ground proposal to help guide the discussion on the call tomorrow. >> >> >> >> A proposal that we have been discussing offline involves reserving a single tag ID for the purpose of construction UEFI PI HOB List structure, and that tag would be used to identify a HOB-specific structure that does leverage UUID based identifier. This will eliminate the burden of having to support UUID as the tag, and this enables projects that require UUID based identifiers for the broad range of HOB structures that need to be produced during the booting of the platform. Once we have a tag for a HOB list, this will enable various HOB producers that can add/extend the HOB list in TF-A code (or even pre-TF-A code), with a HOB consumer for that UUID/GUID on the other side (i.e. whatever the BL33 image is booting on that platform). >> >> >> >> Essentially, the idea is if someone would like to support HOB structures in a standard way using TF-A, they would wrap it up in a BL_AUX_PARAM/BLOB structure (whatever the group decides) and the way we identify the structure as a HOB list is with this new reserved tag. >> >> >> >> Hopefully that makes sense and less contentious. Look forward to discuss this further on the call. >> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: Manish Pandey2 Manish.Pandey2@arm.com >> Sent: Friday, April 30, 2021 8:14 AM >> To: François Ozog francois.ozog@linaro.org >> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> Hi All, >> >> >> >> Please find invite for next TF-A Tech Forum session to continue our discussions on HOB implementation, feel free to forward it to others. >> >> >> >> The next TF-A Tech Forum is scheduled for Thu 6th May 2021 16:00 – 17:00 (BST). >> >> >> >> Agenda: >> >> Discussion Session: Static and Dynamic Information Handling in TF-A >> >> Lead by Manish Pandey and Madhukar Pappireddy >> >> · There is ongoing mailing lists discussion[1] related with adopting a mechanism to pass information through boot stages. >> >> The requirement is two-fold: >> >> 1. Passing static information(config files) >> >> 2. Passing dynamic information (Hob list) >> >> In the upcoming TF-A tech forum, we can start with a discussion on dynamic information passing and if time permits, we can cover static information passing. The purpose of the call is to have an open discussion and continue the discussion from the trusted-substrate call[2] done earlier. We would like to understand the various requirements and possible ways to implement it in TF-A in a generalized way so that it can work with other Firmware projects. >> >> >> >> The two specific item which we would like to discuss are: >> >> 1. HOB format: TF-A/u-boot both has an existing bloblist implementation, which uses tag values. Question, can this be enhanced to use hybrid values(Tag and UUID) both? >> >> 2. Standardization on Physical register use to pass base of HoB data structure. >> >> References: >> >> [1] https://lists.trustedfirmware.org/pipermail/tf-a/2021-April/001069.html >> >> [2] https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q% >> >> >> >> Thanks >> >> >> >> Joanna >> >> >> >> You have been invited to the following event. >> >> TF-A Tech Forum >> >> When >> >> Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time >> >> Calendar >> >> tf-a@lists.trustedfirmware.org >> >> Who >> >> • >> >> Bill Fletcher- creator >> >> • >> >> tf-a@lists.trustedfirmware.org >> >> more details » >> >> >> >> We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC. >> >> >> >> Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/ >> >> >> >> Trusted Firmware is inviting you to a scheduled Zoom meeting. >> >> >> >> Join Zoom Meeting >> >> https://zoom.us/j/9159704974 >> >> >> >> Meeting ID: 915 970 4974 >> >> >> >> One tap mobile >> >> +16465588656,,9159704974# US (New York) >> >> +16699009128,,9159704974# US (San Jose) >> >> >> >> Dial by your location >> >> +1 646 558 8656 US (New York) >> >> +1 669 900 9128 US (San Jose) >> >> 877 853 5247 US Toll-free >> >> 888 788 0099 US Toll-free >> >> Meeting ID: 915 970 4974 >> >> Find your local number: https://zoom.us/u/ad27hc6t7h >> >> >> >> ________________________________ >> >> From: François Ozog francois.ozog@linaro.org >> Sent: 08 April 2021 16:50 >> To: Manish Pandey2 Manish.Pandey2@arm.com >> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> Hi >> >> >> >> here is the meeting recording: >> >> https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%z >> >> >> >> I am really sorry about the confusion related to the meeting time. I have now understood: the Collaborate portal uses a specific calendar which is tied to US/Chicago timezone while the actual Google Calendar is tied to Central Europe timezone. I am going to drop the Collaborate portal and use a shared Google calendar (it should be visible on the trusted-substrate.org page). >> >> >> >> I'll try to summarize what I learnt and highlight my view on what can be next steps in a future mail. >> >> >> >> Cheers >> >> >> >> FF >> >> >> >> On Thu, 8 Apr 2021 at 13:56, Manish Pandey2 via TF-A tf-a@lists.trustedfirmware.org wrote: >> >> Hi, >> >> >> >> From TF-A project point of view, we prefer to use existing mechanism to pass parameters across boot stages using linked list of tagged elements (as suggested by Julius). It has support for both generic and SiP-specific tags. Having said that, it does not stop partners to introduce new mechanisms suitable for their usecase in platform port initially and later move to generic code if its suitable for other platforms. >> >> >> >> To start with, Ampere can introduce a platform specific implementation of memory tag(speed/NUMA topology etc) which can be evaluated and discussed for generalization in future. The tag will be populated in BL2 stage and can be forwarded to further stages(and to BL33) by passing the head of list pointer in one of the registers. Initially any register can be used but going forward a standardization will be needed. >> >> >> >> The U-boot bloblist mentioned by Simon is conceptually similar to what TF-A is using, if there is consensus of using bloblist/taglist then TF-A tag list may be enhanced to take best of both the implementations. >> >> >> >> One of the potential problems of having structure used in different projects is maintainability, this can be avoided by having a single copy of these structures in TF-A (kept inside "include/export" which intended to be used by other projects.) >> >> >> >> Regarding usage of either UUID or tag, I echo the sentiments of Simon and Julius to keep it simple and use tag values. >> >> >> >> Looking forward to having further discussions on zoom call today. >> >> >> >> Thanks >> >> Manish P >> >> >> >> ________________________________ >> >> From: TF-A tf-a-bounces@lists.trustedfirmware.org on behalf of Julius Werner via TF-A tf-a@lists.trustedfirmware.org >> Sent: 25 March 2021 02:43 >> To: Simon Glass sjg@chromium.org >> Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> Just want to point out that TF-A currently already supports a (very simple) mechanism like this: >> >> >> >> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+... >> >> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+... >> >> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+... >> >> >> >> It's just a linked list of tagged elements. The tag space is split into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31. >> >> >> >> I would echo Simon's sentiment of keeping this as simple as possible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once. >> >> >> >> On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A tf-a@lists.trustedfirmware.org wrote: >> >> Hi Harb, >> >> >> >> On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote: >> >> Hello Folks, >> >> Appreciate the feedback and replies on this. Glad to see that there is interest in this topic. >> >> >> >> I try to address the comments/feedback from Francois and Simon below…. >> >> >> >> @François Ozog – happy to discuss this on a zoom call. I will make that time slot work, and will be available to attend April 8, 4pm CT. >> >> >> >> Note that I’m using the term “HOB” here more generically, as there are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases. >> >> >> >> The whole point here is to provide mechanism to develop firmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM). >> >> >> >> Keep in mind, in the server/datacenter market segment we are not building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model: >> >> “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2, BL31, and *possibly* one or more BL32 instances >> “Platform” or “board” firmware – in TF-A this may map to BL33 and *possibly* one or more BL32 instances. >> >> >> >> Even the platform firmware stack could be further fragmented by having multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code. >> >> >> >> To support a broad range of platform designs with a broad range of memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software. >> >> >> >> I understand the versatility of DT, but I see two major problems with DT: >> >> DT requires more complicated parsing to get properties, and even more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained. >> DT is probably overkill for this purpose – We really just want a list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob) >> >> >> >> I think that we should not mix the efforts around DT/ACPI specs with what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs). >> >> >> >> Frankly, I would personally push back pretty hard on defining SMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls. >> >> >> >> Please do let me know if you disagree and why. Look forward to discussing on this thread or on the call. >> >> >> >> @Simon Glass - Thanks for the pointer to bloblist. I briefly reviewed and it seems like a good baseline for what we may be looking for. >> >> >> >> That being said, I would say that there is some benefit in having some kind of unique identifiers (e.g. UUID or some unique signature) so that we can tie standardized data structures (based on some future TBD specs) to a particular ID. For example, if the TPM driver in BL33 is looking for the TPM structure in the HOB/BOB list, and may not care about the other data blobs. The driver needs a way to identify and locate the blob it cares about. >> >> >> >> The tag is intended to serve that purpose, although perhaps it should switch from an auto-allocating enum to one with explicit values for each entry and a range for 'local' use. >> >> >> >> I guess we can achieve this with the tag, but the problem with tag when you have eco-system with a lot of parties doing parallel development, you can end up with tag collisions and folks fighting about who has rights to what tag values. We would need some official process for folks to register tags for whatever new structures we define, or maybe some tag range for vendor specific structures. This comes with a lot of pain and bureaucracy. On the other hand, UUID has been a proven way to make it easy to just define your own blobs with *either* standard or vendor specific structures without worry of ID collisions between vendors. >> >> >> >> True. I think the pain is overstated, though. In this case I think we actually want something that can be shared between projects and orgs, so some amount of coordination could be considered a benefit. It could just be a github pull request. I find the UUID unfriendly and not just to code size and eyesight! Trying to discover what GUIDs mean or are valid is quite tricky. E.g. see this code: >> >> >> >> #define FSP_HOB_RESOURCE_OWNER_TSEG_GUID \ >> EFI_GUID(0xd038747c, 0xd00c, 0x4980, \ >> 0xb3, 0x19, 0x49, 0x01, 0x99, 0xa4, 0x7d, 0x55) >> >> (etc.) >> >> >> >> static struct guid_name { >> efi_guid_t guid; >> const char *name; >> } guid_name[] = { >> { FSP_HOB_RESOURCE_OWNER_TSEG_GUID, "TSEG" }, >> { FSP_HOB_RESOURCE_OWNER_FSP_GUID, "FSP" }, >> { FSP_HOB_RESOURCE_OWNER_SMM_PEI_SMRAM_GUID, "SMM PEI SMRAM" }, >> { FSP_NON_VOLATILE_STORAGE_HOB_GUID, "NVS" }, >> { FSP_VARIABLE_NV_DATA_HOB_GUID, "Variable NVS" }, >> { FSP_GRAPHICS_INFO_HOB_GUID, "Graphics info" }, >> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID1, "PCD database ea" }, >> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID2, "PCD database 9b" }, >> >> (never figured out what those two are) >> >> >> { FSP_HOB_RESOURCE_OWNER_PEIM_DXE_GUID, "PEIM Init DXE" }, >> { FSP_HOB_RESOURCE_OWNER_ALLOC_STACK_GUID, "Alloc stack" }, >> { FSP_HOB_RESOURCE_OWNER_SMBIOS_MEMORY_GUID, "SMBIOS memory" }, >> { {}, "zero-guid" }, >> {} >> }; >> >> static const char *guid_to_name(const efi_guid_t *guid) >> { >> struct guid_name *entry; >> >> for (entry = guid_name; entry->name; entry++) { >> if (!guidcmp(guid, &entry->guid)) >> return entry->name; >> } >> >> return NULL; >> } >> >> >> >> Believe it or not it took a fair bit of effort to find just that small list, with nearly every one in a separate doc, from memory. >> >> >> >> >> >> We can probably debate whether there is any value in GUID/UUID or not during the call… but again, boblist seems like a reasonable starting point as an alternative to HOB. >> >> >> >> Indeed. There is certainly value in both approaches. >> >> >> >> Regards, >> >> Simon >> >> >> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: François Ozog francois.ozog@linaro.org >> Sent: Tuesday, March 23, 2021 10:00 AM >> To: François Ozog francois.ozog@linaro.org; Ron Minnich rminnich@google.com; Paul Isaac's paul.isaacs@linaro.org >> Cc: Simon Glass sjg@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> +Ron Minnich +Paul Isaac's >> >> >> >> Adding Ron and Paul because I think this interface should be also benefiting LinuxBoot efforts. >> >> >> >> On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A tf-a@lists.trustedfirmware.org wrote: >> >> Hi, >> >> >> >> I propose we cover the topic at the next Trusted Substrate zoom call on April 8th 4pm CET. >> >> >> >> The agenda: >> >> ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, S-EL2, SCP) to adapt hardware description to some runtime conditions. >> >> runtime conditions here relates to DRAM size and topology detection, secure DRAM memory carvings, PSCI and SCMI interface publishing. >> >> >> >> For additional background on existing metadata: UEFI Platform Initialization Specification Version 1.7, 5.5 Resource Descriptor HOB >> >> Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY. >> >> This HOB lacks memory NUMA attachment or something that could be related to fill SRAT table for ACPI or relevant DT proximity domains. >> >> HOB is not consistent accros platforms: some platforms (Arm) lists memory from the booting NUMA node, other platforms (x86) lists all memory from all NUMA nodes. (At least this is the case on the two platforms I tested). >> >> >> >> There are two proposals to use memory structures from SPL/BLx up to the handover function (as defined in the Device Tree technical report) which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or EDK2. >> >> I would propose we also discuss possibility of FF-A interface to actually query information or request actions to be done (this is a model actually used in some SoCs with proprietary SMC calls). >> >> >> >> Requirements (to be validated): >> >> - ACPI and DT hardware descriptions. >> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2) >> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, TF-A/LinuxBoot) >> >> - at least allows complete DRAM description and "persistent" usage (reserved areas for secure world or other usages) >> >> - support secure world device assignment >> >> >> >> Cheers >> >> >> >> FF >> >> >> >> >> >> On Mon, 22 Mar 2021 at 19:56, Simon Glass sjg@chromium.org wrote: >> >> Hi, >> >> Can I suggest using bloblist for this instead? It is lightweight, >> easier to parse, doesn't have GUIDs and is already used within U-Boot >> for passing info between SPL/U-Boot, etc. >> >> Docs here: https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist >> Header file describes the format: >> https://github.com/u-boot/u-boot/blob/master/include/bloblist.h >> >> Full set of unit tests: >> https://github.com/u-boot/u-boot/blob/master/test/bloblist.c >> >> Regards, >> Simon >> >> On Mon, 22 Mar 2021 at 23:58, François Ozog francois.ozog@linaro.org wrote: >> > >> > +Boot Architecture Mailman List boot-architecture@lists.linaro.org >> > >> > standardization is very much welcomed here and need to accommodate a very >> > diverse set of situations. >> > For example, TEE OS may need to pass memory reservations to BL33 or >> > "capture" a device for the secure world. >> > >> > I have observed a number of architectures: >> > 1) pass information from BLx to BLy in the form of a specific object >> > 2) BLx called by BLy by a platform specific SMC to get information >> > 3) BLx called by BLy by a platform specific SMC to perform Device Tree >> > fixups >> > >> > I also imagined a standardized "broadcast" FF-A call so that any firmware >> > element can either provide information or "do something". >> > >> > My understanding of your proposal is about standardizing on architecture 1) >> > with the HOB format. >> > >> > The advantage of the HOB is simplicity but it may be difficult to implement >> > schemes such as pruning a DT because device assignment in the secure world. >> > >> > In any case, it looks feasible to have TF-A and OP-TEE complement the list >> > of HOBs to pass information downstream (the bootflow). >> > >> > It would be good to start with building the comprehensive list of >> > information that need to be conveyed between firmware elements: >> > >> > information. | authoritative entity | reporting entity | information >> > exchanged: >> > dram | TFA | TFA | >> > <format to be detailed, NUMA topology to build the SRAT table or DT >> > equivalent?> >> > PSCI | SCP | TFA? | >> > SCMI | SCP or TEE-OS | TFA? TEE-OS?| >> > secure SRAM | TFA. | TFA. | >> > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | >> > other? | | >> > | >> > >> > Cheers >> > >> > FF >> > >> > >> > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < >> > tf-a@lists.trustedfirmware.org> wrote: >> > >> > > Hello Folks, >> > > >> > > >> > > >> > > I'm emailing to start an open discussion about the adoption of a concept >> > > known as "hand-off blocks" or HOB to become a part of the TF-A Firmware >> > > Framework Architecture (FFA). This is something that is a pretty major >> > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s >> > > designed to enable a broad range of highly configurable datacenter >> > > platforms. >> > > >> > > >> > > >> > > >> > > >> > > What is a HOB (Background)? >> > > >> > > --------------------------- >> > > >> > > UEFI PI spec describes a particular definition for how HOB may be used for >> > > transitioning between the PEI and DXE boot phases, which is a good >> > > reference point for this discussion, but not necessarily the exact solution >> > > appropriate for TF-A. >> > > >> > > >> > > >> > > A HOB is simply a dynamically generated data structure passed in between >> > > two boot phases. This is information that was obtained through discovery >> > > and needs to be passed forward to the next boot phase *once*, with no API >> > > needed to call back (e.g. no call back into previous firmware phase is >> > > needed to fetch this information at run-time - it is simply passed one time >> > > during boot). >> > > >> > > >> > > >> > > There may be one or more HOBs passed in between boot phases. If there are >> > > more than one HOB that needs to be passed, this can be in a form of a "HOB >> > > table", which (for example) could be a UUID indexed array of pointers to >> > > HOB structures, used to locate a HOB of interest (based on UUID). In such >> > > cases, instead of passing a single HOB, the boot phases may rely on passing >> > > the pointer to the HOB table. >> > > >> > > >> > > >> > > This has been extremely useful concept to employ on highly configurable >> > > systems that must rely on flexible discovery mechanisms to initialize and >> > > boot the system. This is especially helpful when you have multiple >> > > >> > > >> > > >> > > >> > > >> > > Why do we need HOBs in TF-A?: >> > > >> > > ----------------------------- >> > > >> > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server SoC in >> > > a way that is SoC specific *but* platform agnostic. This means that a >> > > single ARM SoC that a SiP may deliver to customers may provide a single >> > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a broad >> > > range of platform designs and configurations in order to boot a platform >> > > specific firmware (e.g. BL33 and possibly even BL32 code). In order to >> > > achieve this, the platform configuration must be *discovered* instead of >> > > statically compiled as it is today in TF-A via device tree based >> > > enumeration. The mechanisms of discovery may differ broadly depending on >> > > the relevant industry standard, or in some cases may have rely on SiP >> > > specific discovery flows. >> > > >> > > >> > > >> > > For example: On server systems that support a broad range DIMM memory >> > > population/topologies, all the necessary information required to boot is >> > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over an >> > > I2C bus. Leveraging the SPD bus, may platform variants could be supported >> > > with a single TF-A binary. Not only is this information required to >> > > initialize memory in early boot phases (e.g. BL2), the subsequent boot >> > > phases will also need this SPD info to construct a system physical address >> > > map and properly initialize the MMU based on the memory present, and where >> > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) may >> > > need to generate standard firmware tables to the operating systems, such as >> > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. SLIT, >> > > SRAT, even NFIT if NVDIMM's are present). >> > > >> > > >> > > >> > > In short, it all starts with a standardized or vendor specific discovery >> > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of >> > > information to the next boot stages (e.g. BL31/BL32/BL33). >> > > >> > > >> > > >> > > Today, every HOB may be a vendor specific structure, but in the future >> > > there may be benefit of defining standard HOBs. This may be useful for >> > > memory discovery, passing the system physical address map, enabling TPM >> > > measured boot, and potentially many other common HOB use-cases. >> > > >> > > >> > > >> > > It would be extremely beneficial to the datacenter market segment if the >> > > TF-A community would adopt this concept of information passing between all >> > > boot phases as opposed to rely solely on device tree enumeration. This is >> > > not intended to replace device tree, rather intended as an alternative way >> > > to describe the info that must be discovered and dynamically generated. >> > > >> > > >> > > >> > > >> > > >> > > Conclusion: >> > > >> > > ----------- >> > > >> > > We are proposing that the TF-A community begin pursuing the adoption of >> > > HOBs as a mechanism used for information exchange between each boot stage >> > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term we >> > > want to explore standardizing some HOB structures for the BL33 phase (e.g. >> > > UEFI HOB structures), but initially would like to agree on this being a >> > > useful mechanism used to pass information between each boot stage. >> > > >> > > >> > > >> > > Thanks, >> > > >> > > --Harb >> > > >> > > >> > > >> > > >> > > >> > > >> > > -- >> > > TF-A mailing list >> > > TF-A@lists.trustedfirmware.org >> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> > > >> > >> > >> > -- >> > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* >> > T: +33.67221.6485 >> > francois.ozog@linaro.org | Skype: ffozog >> > _______________________________________________ >> > boot-architecture mailing list >> > boot-architecture@lists.linaro.org >> > https://lists.linaro.org/mailman/listinfo/boot-architecture >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group >> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group >> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group >> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> > > -- > TF-A mailing list > TF-A@lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a
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Looks tf-a@lists.trustedfirmware.org got dropped. Adding that back in.
Joanna
On 19/05/2021, 15:33, "Joanna Farley" Joanna.Farley@arm.com wrote:
It’s a bit short notice to host another TF-A Tech-forum call on this tomorrow for a live debate as well as Manish who led the call last time is not available this week. So I propose our next TF-A Techforum session on Thursday 3rd June at 4pm BST and between now and then email discussions can possibly be pursued.
From a TF-A perspective we want to help facilitate a number of segments/use-cases we heard about as Madhu mentions below. As such any enablement we can provide in TF-A common code would be good to identify that contributors to other segments/use-cases can build upon in shared platform code in TF-A or elsewhere outside the TF-A repository of that works better for those segments/use-cases.
Thanks
Joanna
On 19/05/2021, 03:50, "Madhukar Pappireddy" Madhukar.Pappireddy@arm.com wrote:
Attached slides presented by Manish in the TF-A tech forum.
-----Original Message----- From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Madhukar Pappireddy via TF-A Sent: Tuesday, May 18, 2021 8:59 PM To: Joanna Farley Joanna.Farley@arm.com; Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; tf-a@lists.trustedfirmware.org; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi,
I tried to summarize the discussions in the previous TF-A tech forum regarding the proposal to adopt Hand-off Blocks (HOBs) for passing information along the boot chain. I am certain I could not capture all suggestions/concerns brought up during the call. I apologize if I missed and/or misinterpreted any comments and would appreciate it if everyone could share their thoughts in response to this email thread.
The idea is to share information to other boot phases: > Dynamic information: Created during runtime. Shared in the form of a chain of blobs(built as a linked list of C structure objects i.e., HOB list). > Static information: Known at compile time. Historically, shared through the use of Device Tree/ACPI tables
Both the above requirements are common in many ecosystems and need to co-exist.
There are broadly 3 problems to solve: 1. Format of HOB structures: It looks like the consensus is that we could use existing mechanisms for this (BL_AUX_PARAM in TF-A or bloblist in u-boot). 2. Identification of HOB list entries: There is a debate about whether tags would suffice or if the HOB list producer and consumer would depend on UUID/GUIDs for identifying a specific HOB structure. Another suggestion was to use a hybrid approach. Reserve a single tag ID for identifying/constructing a HOB structure that further leverages UUID based identifier. This way, the generic HOB list doesn't need to support UUIDs and can work with tags. 3. The design contract for the static interface between two boot phases: The problem at hand is whether to pass a pointer to a HOB list or a device tree blob through the general-purpose registers for configuration hand-off between two boot phases. Some proposals that came up: > Proposal 1: Always pass a pointer to the device tree blob through the GP register and capture the pointer to the HOB list as a property of a node that is uniquely identifiable by the downstream boot phase. This needs to define a device tree binding such that producer and consumer agree on the information passed. > Proposal 2: Pass a pointer to a generic container through the GP register that can be interpreted appropriately by both boot loaders(i.e., producer and consumer of the boot info). This container can either be a dtb or a HOB list which can be simply inferred by checking for a magic header that indicates if the buffer appears to be a flattened device tree. > One another concern that was brought up offline is to make sure we don't break current design contracts between various boot loader phases in TF-A. Many of the general-purpose registers have a designated purpose such as to share configurations between BL images( such as firmware config dtb, SoC config dtb, Non trusted firmware config dtb, memory layout, entry point info, etc.).
If I am not mistaken, a single design may not fit the needs of every segment(client, Infra, embedded) and the forum is open to solutions tailored for individual segments. Joanna will be sending a follow up email with more information about future TF-A tech forums that serves as a platform for further discussions.
Thanks, Madhukar
-----Original Message----- From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Joanna Farley via TF-A Sent: Sunday, May 16, 2021 5:19 AM To: Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Apologies I failed with the recording. Manish/Madhu will reply early next week with the slides and some notes to help with a follow up session which we hope to hold this Thursday. Invite and agenda will also be sent out early next week.
Thanks
Joanna
On 14/05/2021, 13:30, "TF-A on behalf of Okash Khawaja via TF-A" <tf-a-bounces@lists.trustedfirmware.org on behalf of tf-a@lists.trustedfirmware.org> wrote:
Hi,
Do we have slides and video from last week's discussion?
Thanks, Okash
On Wed, May 5, 2021 at 11:52 PM Simon Glass via TF-A tf-a@lists.trustedfirmware.org wrote: > > Hi Harb, > > Thanks for the idea. I am still not completely sure what benefit UUID provides to an open project. I'd like to propose something different, more in the spirit of open collaboration. I also worry that the word 'standard' seems to be a synonym for UUIDs, UEFI, etc., i.e. enabling/preferring closed-source firmware and the continued decline of open-source projects. It really should not be. > > So I suggest: Use simple integer IDs and reserve some area for 'private' use. If you want to collaborate across projects outside your company, you either need to allocate a 'public' ID or agree privately between the parties which private ID to use. > > This means that the default and easiest option is for collaboration and a public ID, with private ones (whose purpose may be secret) reserved just for private use. > > Regards, > Simon > > On Wed, 5 May 2021 at 11:42, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote: >> >> Hey Folks, >> >> We wanted to put out a middle-ground proposal to help guide the discussion on the call tomorrow. >> >> >> >> A proposal that we have been discussing offline involves reserving a single tag ID for the purpose of construction UEFI PI HOB List structure, and that tag would be used to identify a HOB-specific structure that does leverage UUID based identifier. This will eliminate the burden of having to support UUID as the tag, and this enables projects that require UUID based identifiers for the broad range of HOB structures that need to be produced during the booting of the platform. Once we have a tag for a HOB list, this will enable various HOB producers that can add/extend the HOB list in TF-A code (or even pre-TF-A code), with a HOB consumer for that UUID/GUID on the other side (i.e. whatever the BL33 image is booting on that platform). >> >> >> >> Essentially, the idea is if someone would like to support HOB structures in a standard way using TF-A, they would wrap it up in a BL_AUX_PARAM/BLOB structure (whatever the group decides) and the way we identify the structure as a HOB list is with this new reserved tag. >> >> >> >> Hopefully that makes sense and less contentious. Look forward to discuss this further on the call. >> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: Manish Pandey2 Manish.Pandey2@arm.com >> Sent: Friday, April 30, 2021 8:14 AM >> To: François Ozog francois.ozog@linaro.org >> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> Hi All, >> >> >> >> Please find invite for next TF-A Tech Forum session to continue our discussions on HOB implementation, feel free to forward it to others. >> >> >> >> The next TF-A Tech Forum is scheduled for Thu 6th May 2021 16:00 – 17:00 (BST). >> >> >> >> Agenda: >> >> Discussion Session: Static and Dynamic Information Handling in TF-A >> >> Lead by Manish Pandey and Madhukar Pappireddy >> >> · There is ongoing mailing lists discussion[1] related with adopting a mechanism to pass information through boot stages. >> >> The requirement is two-fold: >> >> 1. Passing static information(config files) >> >> 2. Passing dynamic information (Hob list) >> >> In the upcoming TF-A tech forum, we can start with a discussion on dynamic information passing and if time permits, we can cover static information passing. The purpose of the call is to have an open discussion and continue the discussion from the trusted-substrate call[2] done earlier. We would like to understand the various requirements and possible ways to implement it in TF-A in a generalized way so that it can work with other Firmware projects. >> >> >> >> The two specific item which we would like to discuss are: >> >> 1. HOB format: TF-A/u-boot both has an existing bloblist implementation, which uses tag values. Question, can this be enhanced to use hybrid values(Tag and UUID) both? >> >> 2. Standardization on Physical register use to pass base of HoB data structure. >> >> References: >> >> [1] https://lists.trustedfirmware.org/pipermail/tf-a/2021-April/001069.html >> >> [2] https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q% >> >> >> >> Thanks >> >> >> >> Joanna >> >> >> >> You have been invited to the following event. >> >> TF-A Tech Forum >> >> When >> >> Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time >> >> Calendar >> >> tf-a@lists.trustedfirmware.org >> >> Who >> >> • >> >> Bill Fletcher- creator >> >> • >> >> tf-a@lists.trustedfirmware.org >> >> more details » >> >> >> >> We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC. >> >> >> >> Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/ >> >> >> >> Trusted Firmware is inviting you to a scheduled Zoom meeting. >> >> >> >> Join Zoom Meeting >> >> https://zoom.us/j/9159704974 >> >> >> >> Meeting ID: 915 970 4974 >> >> >> >> One tap mobile >> >> +16465588656,,9159704974# US (New York) >> >> +16699009128,,9159704974# US (San Jose) >> >> >> >> Dial by your location >> >> +1 646 558 8656 US (New York) >> >> +1 669 900 9128 US (San Jose) >> >> 877 853 5247 US Toll-free >> >> 888 788 0099 US Toll-free >> >> Meeting ID: 915 970 4974 >> >> Find your local number: https://zoom.us/u/ad27hc6t7h >> >> >> >> ________________________________ >> >> From: François Ozog francois.ozog@linaro.org >> Sent: 08 April 2021 16:50 >> To: Manish Pandey2 Manish.Pandey2@arm.com >> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> Hi >> >> >> >> here is the meeting recording: >> >> https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%z >> >> >> >> I am really sorry about the confusion related to the meeting time. I have now understood: the Collaborate portal uses a specific calendar which is tied to US/Chicago timezone while the actual Google Calendar is tied to Central Europe timezone. I am going to drop the Collaborate portal and use a shared Google calendar (it should be visible on the trusted-substrate.org page). >> >> >> >> I'll try to summarize what I learnt and highlight my view on what can be next steps in a future mail. >> >> >> >> Cheers >> >> >> >> FF >> >> >> >> On Thu, 8 Apr 2021 at 13:56, Manish Pandey2 via TF-A tf-a@lists.trustedfirmware.org wrote: >> >> Hi, >> >> >> >> From TF-A project point of view, we prefer to use existing mechanism to pass parameters across boot stages using linked list of tagged elements (as suggested by Julius). It has support for both generic and SiP-specific tags. Having said that, it does not stop partners to introduce new mechanisms suitable for their usecase in platform port initially and later move to generic code if its suitable for other platforms. >> >> >> >> To start with, Ampere can introduce a platform specific implementation of memory tag(speed/NUMA topology etc) which can be evaluated and discussed for generalization in future. The tag will be populated in BL2 stage and can be forwarded to further stages(and to BL33) by passing the head of list pointer in one of the registers. Initially any register can be used but going forward a standardization will be needed. >> >> >> >> The U-boot bloblist mentioned by Simon is conceptually similar to what TF-A is using, if there is consensus of using bloblist/taglist then TF-A tag list may be enhanced to take best of both the implementations. >> >> >> >> One of the potential problems of having structure used in different projects is maintainability, this can be avoided by having a single copy of these structures in TF-A (kept inside "include/export" which intended to be used by other projects.) >> >> >> >> Regarding usage of either UUID or tag, I echo the sentiments of Simon and Julius to keep it simple and use tag values. >> >> >> >> Looking forward to having further discussions on zoom call today. >> >> >> >> Thanks >> >> Manish P >> >> >> >> ________________________________ >> >> From: TF-A tf-a-bounces@lists.trustedfirmware.org on behalf of Julius Werner via TF-A tf-a@lists.trustedfirmware.org >> Sent: 25 March 2021 02:43 >> To: Simon Glass sjg@chromium.org >> Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> Just want to point out that TF-A currently already supports a (very simple) mechanism like this: >> >> >> >> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+... >> >> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+... >> >> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+... >> >> >> >> It's just a linked list of tagged elements. The tag space is split into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31. >> >> >> >> I would echo Simon's sentiment of keeping this as simple as possible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once. >> >> >> >> On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A tf-a@lists.trustedfirmware.org wrote: >> >> Hi Harb, >> >> >> >> On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote: >> >> Hello Folks, >> >> Appreciate the feedback and replies on this. Glad to see that there is interest in this topic. >> >> >> >> I try to address the comments/feedback from Francois and Simon below…. >> >> >> >> @François Ozog – happy to discuss this on a zoom call. I will make that time slot work, and will be available to attend April 8, 4pm CT. >> >> >> >> Note that I’m using the term “HOB” here more generically, as there are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases. >> >> >> >> The whole point here is to provide mechanism to develop firmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM). >> >> >> >> Keep in mind, in the server/datacenter market segment we are not building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model: >> >> “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2, BL31, and *possibly* one or more BL32 instances >> “Platform” or “board” firmware – in TF-A this may map to BL33 and *possibly* one or more BL32 instances. >> >> >> >> Even the platform firmware stack could be further fragmented by having multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code. >> >> >> >> To support a broad range of platform designs with a broad range of memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software. >> >> >> >> I understand the versatility of DT, but I see two major problems with DT: >> >> DT requires more complicated parsing to get properties, and even more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained. >> DT is probably overkill for this purpose – We really just want a list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob) >> >> >> >> I think that we should not mix the efforts around DT/ACPI specs with what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs). >> >> >> >> Frankly, I would personally push back pretty hard on defining SMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls. >> >> >> >> Please do let me know if you disagree and why. Look forward to discussing on this thread or on the call. >> >> >> >> @Simon Glass - Thanks for the pointer to bloblist. I briefly reviewed and it seems like a good baseline for what we may be looking for. >> >> >> >> That being said, I would say that there is some benefit in having some kind of unique identifiers (e.g. UUID or some unique signature) so that we can tie standardized data structures (based on some future TBD specs) to a particular ID. For example, if the TPM driver in BL33 is looking for the TPM structure in the HOB/BOB list, and may not care about the other data blobs. The driver needs a way to identify and locate the blob it cares about. >> >> >> >> The tag is intended to serve that purpose, although perhaps it should switch from an auto-allocating enum to one with explicit values for each entry and a range for 'local' use. >> >> >> >> I guess we can achieve this with the tag, but the problem with tag when you have eco-system with a lot of parties doing parallel development, you can end up with tag collisions and folks fighting about who has rights to what tag values. We would need some official process for folks to register tags for whatever new structures we define, or maybe some tag range for vendor specific structures. This comes with a lot of pain and bureaucracy. On the other hand, UUID has been a proven way to make it easy to just define your own blobs with *either* standard or vendor specific structures without worry of ID collisions between vendors. >> >> >> >> True. I think the pain is overstated, though. In this case I think we actually want something that can be shared between projects and orgs, so some amount of coordination could be considered a benefit. It could just be a github pull request. I find the UUID unfriendly and not just to code size and eyesight! Trying to discover what GUIDs mean or are valid is quite tricky. E.g. see this code: >> >> >> >> #define FSP_HOB_RESOURCE_OWNER_TSEG_GUID \ >> EFI_GUID(0xd038747c, 0xd00c, 0x4980, \ >> 0xb3, 0x19, 0x49, 0x01, 0x99, 0xa4, 0x7d, 0x55) >> >> (etc.) >> >> >> >> static struct guid_name { >> efi_guid_t guid; >> const char *name; >> } guid_name[] = { >> { FSP_HOB_RESOURCE_OWNER_TSEG_GUID, "TSEG" }, >> { FSP_HOB_RESOURCE_OWNER_FSP_GUID, "FSP" }, >> { FSP_HOB_RESOURCE_OWNER_SMM_PEI_SMRAM_GUID, "SMM PEI SMRAM" }, >> { FSP_NON_VOLATILE_STORAGE_HOB_GUID, "NVS" }, >> { FSP_VARIABLE_NV_DATA_HOB_GUID, "Variable NVS" }, >> { FSP_GRAPHICS_INFO_HOB_GUID, "Graphics info" }, >> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID1, "PCD database ea" }, >> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID2, "PCD database 9b" }, >> >> (never figured out what those two are) >> >> >> { FSP_HOB_RESOURCE_OWNER_PEIM_DXE_GUID, "PEIM Init DXE" }, >> { FSP_HOB_RESOURCE_OWNER_ALLOC_STACK_GUID, "Alloc stack" }, >> { FSP_HOB_RESOURCE_OWNER_SMBIOS_MEMORY_GUID, "SMBIOS memory" }, >> { {}, "zero-guid" }, >> {} >> }; >> >> static const char *guid_to_name(const efi_guid_t *guid) >> { >> struct guid_name *entry; >> >> for (entry = guid_name; entry->name; entry++) { >> if (!guidcmp(guid, &entry->guid)) >> return entry->name; >> } >> >> return NULL; >> } >> >> >> >> Believe it or not it took a fair bit of effort to find just that small list, with nearly every one in a separate doc, from memory. >> >> >> >> >> >> We can probably debate whether there is any value in GUID/UUID or not during the call… but again, boblist seems like a reasonable starting point as an alternative to HOB. >> >> >> >> Indeed. There is certainly value in both approaches. >> >> >> >> Regards, >> >> Simon >> >> >> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: François Ozog francois.ozog@linaro.org >> Sent: Tuesday, March 23, 2021 10:00 AM >> To: François Ozog francois.ozog@linaro.org; Ron Minnich rminnich@google.com; Paul Isaac's paul.isaacs@linaro.org >> Cc: Simon Glass sjg@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org >> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages >> >> >> >> +Ron Minnich +Paul Isaac's >> >> >> >> Adding Ron and Paul because I think this interface should be also benefiting LinuxBoot efforts. >> >> >> >> On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A tf-a@lists.trustedfirmware.org wrote: >> >> Hi, >> >> >> >> I propose we cover the topic at the next Trusted Substrate zoom call on April 8th 4pm CET. >> >> >> >> The agenda: >> >> ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, S-EL2, SCP) to adapt hardware description to some runtime conditions. >> >> runtime conditions here relates to DRAM size and topology detection, secure DRAM memory carvings, PSCI and SCMI interface publishing. >> >> >> >> For additional background on existing metadata: UEFI Platform Initialization Specification Version 1.7, 5.5 Resource Descriptor HOB >> >> Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY. >> >> This HOB lacks memory NUMA attachment or something that could be related to fill SRAT table for ACPI or relevant DT proximity domains. >> >> HOB is not consistent accros platforms: some platforms (Arm) lists memory from the booting NUMA node, other platforms (x86) lists all memory from all NUMA nodes. (At least this is the case on the two platforms I tested). >> >> >> >> There are two proposals to use memory structures from SPL/BLx up to the handover function (as defined in the Device Tree technical report) which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or EDK2. >> >> I would propose we also discuss possibility of FF-A interface to actually query information or request actions to be done (this is a model actually used in some SoCs with proprietary SMC calls). >> >> >> >> Requirements (to be validated): >> >> - ACPI and DT hardware descriptions. >> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2) >> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, TF-A/LinuxBoot) >> >> - at least allows complete DRAM description and "persistent" usage (reserved areas for secure world or other usages) >> >> - support secure world device assignment >> >> >> >> Cheers >> >> >> >> FF >> >> >> >> >> >> On Mon, 22 Mar 2021 at 19:56, Simon Glass sjg@chromium.org wrote: >> >> Hi, >> >> Can I suggest using bloblist for this instead? It is lightweight, >> easier to parse, doesn't have GUIDs and is already used within U-Boot >> for passing info between SPL/U-Boot, etc. >> >> Docs here: https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist >> Header file describes the format: >> https://github.com/u-boot/u-boot/blob/master/include/bloblist.h >> >> Full set of unit tests: >> https://github.com/u-boot/u-boot/blob/master/test/bloblist.c >> >> Regards, >> Simon >> >> On Mon, 22 Mar 2021 at 23:58, François Ozog francois.ozog@linaro.org wrote: >> > >> > +Boot Architecture Mailman List boot-architecture@lists.linaro.org >> > >> > standardization is very much welcomed here and need to accommodate a very >> > diverse set of situations. >> > For example, TEE OS may need to pass memory reservations to BL33 or >> > "capture" a device for the secure world. >> > >> > I have observed a number of architectures: >> > 1) pass information from BLx to BLy in the form of a specific object >> > 2) BLx called by BLy by a platform specific SMC to get information >> > 3) BLx called by BLy by a platform specific SMC to perform Device Tree >> > fixups >> > >> > I also imagined a standardized "broadcast" FF-A call so that any firmware >> > element can either provide information or "do something". >> > >> > My understanding of your proposal is about standardizing on architecture 1) >> > with the HOB format. >> > >> > The advantage of the HOB is simplicity but it may be difficult to implement >> > schemes such as pruning a DT because device assignment in the secure world. >> > >> > In any case, it looks feasible to have TF-A and OP-TEE complement the list >> > of HOBs to pass information downstream (the bootflow). >> > >> > It would be good to start with building the comprehensive list of >> > information that need to be conveyed between firmware elements: >> > >> > information. | authoritative entity | reporting entity | information >> > exchanged: >> > dram | TFA | TFA | >> > <format to be detailed, NUMA topology to build the SRAT table or DT >> > equivalent?> >> > PSCI | SCP | TFA? | >> > SCMI | SCP or TEE-OS | TFA? TEE-OS?| >> > secure SRAM | TFA. | TFA. | >> > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | >> > other? | | >> > | >> > >> > Cheers >> > >> > FF >> > >> > >> > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < >> > tf-a@lists.trustedfirmware.org> wrote: >> > >> > > Hello Folks, >> > > >> > > >> > > >> > > I'm emailing to start an open discussion about the adoption of a concept >> > > known as "hand-off blocks" or HOB to become a part of the TF-A Firmware >> > > Framework Architecture (FFA). This is something that is a pretty major >> > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s >> > > designed to enable a broad range of highly configurable datacenter >> > > platforms. >> > > >> > > >> > > >> > > >> > > >> > > What is a HOB (Background)? >> > > >> > > --------------------------- >> > > >> > > UEFI PI spec describes a particular definition for how HOB may be used for >> > > transitioning between the PEI and DXE boot phases, which is a good >> > > reference point for this discussion, but not necessarily the exact solution >> > > appropriate for TF-A. >> > > >> > > >> > > >> > > A HOB is simply a dynamically generated data structure passed in between >> > > two boot phases. This is information that was obtained through discovery >> > > and needs to be passed forward to the next boot phase *once*, with no API >> > > needed to call back (e.g. no call back into previous firmware phase is >> > > needed to fetch this information at run-time - it is simply passed one time >> > > during boot). >> > > >> > > >> > > >> > > There may be one or more HOBs passed in between boot phases. If there are >> > > more than one HOB that needs to be passed, this can be in a form of a "HOB >> > > table", which (for example) could be a UUID indexed array of pointers to >> > > HOB structures, used to locate a HOB of interest (based on UUID). In such >> > > cases, instead of passing a single HOB, the boot phases may rely on passing >> > > the pointer to the HOB table. >> > > >> > > >> > > >> > > This has been extremely useful concept to employ on highly configurable >> > > systems that must rely on flexible discovery mechanisms to initialize and >> > > boot the system. This is especially helpful when you have multiple >> > > >> > > >> > > >> > > >> > > >> > > Why do we need HOBs in TF-A?: >> > > >> > > ----------------------------- >> > > >> > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server SoC in >> > > a way that is SoC specific *but* platform agnostic. This means that a >> > > single ARM SoC that a SiP may deliver to customers may provide a single >> > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a broad >> > > range of platform designs and configurations in order to boot a platform >> > > specific firmware (e.g. BL33 and possibly even BL32 code). In order to >> > > achieve this, the platform configuration must be *discovered* instead of >> > > statically compiled as it is today in TF-A via device tree based >> > > enumeration. The mechanisms of discovery may differ broadly depending on >> > > the relevant industry standard, or in some cases may have rely on SiP >> > > specific discovery flows. >> > > >> > > >> > > >> > > For example: On server systems that support a broad range DIMM memory >> > > population/topologies, all the necessary information required to boot is >> > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over an >> > > I2C bus. Leveraging the SPD bus, may platform variants could be supported >> > > with a single TF-A binary. Not only is this information required to >> > > initialize memory in early boot phases (e.g. BL2), the subsequent boot >> > > phases will also need this SPD info to construct a system physical address >> > > map and properly initialize the MMU based on the memory present, and where >> > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) may >> > > need to generate standard firmware tables to the operating systems, such as >> > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. SLIT, >> > > SRAT, even NFIT if NVDIMM's are present). >> > > >> > > >> > > >> > > In short, it all starts with a standardized or vendor specific discovery >> > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of >> > > information to the next boot stages (e.g. BL31/BL32/BL33). >> > > >> > > >> > > >> > > Today, every HOB may be a vendor specific structure, but in the future >> > > there may be benefit of defining standard HOBs. This may be useful for >> > > memory discovery, passing the system physical address map, enabling TPM >> > > measured boot, and potentially many other common HOB use-cases. >> > > >> > > >> > > >> > > It would be extremely beneficial to the datacenter market segment if the >> > > TF-A community would adopt this concept of information passing between all >> > > boot phases as opposed to rely solely on device tree enumeration. This is >> > > not intended to replace device tree, rather intended as an alternative way >> > > to describe the info that must be discovered and dynamically generated. >> > > >> > > >> > > >> > > >> > > >> > > Conclusion: >> > > >> > > ----------- >> > > >> > > We are proposing that the TF-A community begin pursuing the adoption of >> > > HOBs as a mechanism used for information exchange between each boot stage >> > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term we >> > > want to explore standardizing some HOB structures for the BL33 phase (e.g. >> > > UEFI HOB structures), but initially would like to agree on this being a >> > > useful mechanism used to pass information between each boot stage. >> > > >> > > >> > > >> > > Thanks, >> > > >> > > --Harb >> > > >> > > >> > > >> > > >> > > >> > > >> > > -- >> > > TF-A mailing list >> > > TF-A@lists.trustedfirmware.org >> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> > > >> > >> > >> > -- >> > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* >> > T: +33.67221.6485 >> > francois.ozog@linaro.org | Skype: ffozog >> > _______________________________________________ >> > boot-architecture mailing list >> > boot-architecture@lists.linaro.org >> > https://lists.linaro.org/mailman/listinfo/boot-architecture >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group >> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group >> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group >> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> > > -- > TF-A mailing list > TF-A@lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a
-- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a
Hi Everyone,
The Manish Pandy and Madhukar Pappireddy of the TF-A team are planning to host another TF-A Tech Forum this Thursday to continue the live discussion.
Here is their agenda:
On tech forum this week, we would like to continue discussions on HOB list design.
The topics which we would like to cover is
1. Evaluate different proposals of passing information through boot phases.
2. If we don't get an agreement on one solution fit for all then we would try to get consensus for Infra segment platform(to solve original problem mentioned by Harb)
3. Try to get an agreement on size of tags and how "hybrid and tag only" HOB list can co-exist together?
Details of the call are:
======================
TF-A Tech Forum
When Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time
Calendar tf-a@lists.trustedfirmware.org
Who • Bill Fletcher- creator
• tf-a@lists.trustedfirmware.org
We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
Trusted Firmware is inviting you to a scheduled Zoom meeting.
Join Zoom Meeting
Meeting ID: 915 970 4974
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================
Joanna
On 19/05/2021, 03:50, "Madhukar Pappireddy" Madhukar.Pappireddy@arm.com wrote:
Attached slides presented by Manish in the TF-A tech forum.
-----Original Message-----
From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Madhukar Pappireddy via TF-A
Sent: Tuesday, May 18, 2021 8:59 PM
To: Joanna Farley Joanna.Farley@arm.com; Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org
Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; tf-a@lists.trustedfirmware.org; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi,
I tried to summarize the discussions in the previous TF-A tech forum regarding the proposal to adopt Hand-off Blocks (HOBs) for passing information along the boot chain. I am certain I could not capture all suggestions/concerns brought up during the call. I apologize if I missed and/or misinterpreted any comments and would appreciate it if everyone could share their thoughts in response to this email thread.
The idea is to share information to other boot phases:
> Dynamic information: Created during runtime. Shared in the form of a chain of blobs(built as a linked list of C structure objects i.e., HOB list).
> Static information: Known at compile time. Historically, shared through the use of Device Tree/ACPI tables
Both the above requirements are common in many ecosystems and need to co-exist.
There are broadly 3 problems to solve:
1. Format of HOB structures: It looks like the consensus is that we could use existing mechanisms for this (BL_AUX_PARAM in TF-A or bloblist in u-boot).
2. Identification of HOB list entries: There is a debate about whether tags would suffice or if the HOB list producer and consumer would depend on UUID/GUIDs for identifying a specific HOB structure. Another suggestion was to use a hybrid approach. Reserve a single tag ID for identifying/constructing a HOB structure that further leverages UUID based identifier. This way, the generic HOB list doesn't need to support UUIDs and can work with tags.
3. The design contract for the static interface between two boot phases: The problem at hand is whether to pass a pointer to a HOB list or a device tree blob through the general-purpose registers for configuration hand-off between two boot phases. Some proposals that came up:
> Proposal 1: Always pass a pointer to the device tree blob through the GP register and capture the pointer to the HOB list as a property of a node that is uniquely identifiable by the downstream boot phase. This needs to define a device tree binding such that producer and consumer agree on the information passed.
> Proposal 2: Pass a pointer to a generic container through the GP register that can be interpreted appropriately by both boot loaders(i.e., producer and consumer of the boot info). This container can either be a dtb or a HOB list which can be simply inferred by checking for a magic header that indicates if the buffer appears to be a flattened device tree.
> One another concern that was brought up offline is to make sure we don't break current design contracts between various boot loader phases in TF-A. Many of the general-purpose registers have a designated purpose such as to share configurations between BL images( such as firmware config dtb, SoC config dtb, Non trusted firmware config dtb, memory layout, entry point info, etc.).
If I am not mistaken, a single design may not fit the needs of every segment(client, Infra, embedded) and the forum is open to solutions tailored for individual segments. Joanna will be sending a follow up email with more information about future TF-A tech forums that serves as a platform for further discussions.
Thanks,
Madhukar
-----Original Message-----
From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Joanna Farley via TF-A
Sent: Sunday, May 16, 2021 5:19 AM
To: Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org
Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Apologies I failed with the recording. Manish/Madhu will reply early next week with the slides and some notes to help with a follow up session which we hope to hold this Thursday. Invite and agenda will also be sent out early next week.
Thanks
Joanna
On 14/05/2021, 13:30, "TF-A on behalf of Okash Khawaja via TF-A" <tf-a-bounces@lists.trustedfirmware.org on behalf of tf-a@lists.trustedfirmware.org> wrote:
Hi,
Do we have slides and video from last week's discussion?
Thanks,
Okash
On Wed, May 5, 2021 at 11:52 PM Simon Glass via TF-A
tf-a@lists.trustedfirmware.org wrote:
>
> Hi Harb,
>
> Thanks for the idea. I am still not completely sure what benefit UUID provides to an open project. I'd like to propose something different, more in the spirit of open collaboration. I also worry that the word 'standard' seems to be a synonym for UUIDs, UEFI, etc., i.e. enabling/preferring closed-source firmware and the continued decline of open-source projects. It really should not be.
>
> So I suggest: Use simple integer IDs and reserve some area for 'private' use. If you want to collaborate across projects outside your company, you either need to allocate a 'public' ID or agree privately between the parties which private ID to use.
>
> This means that the default and easiest option is for collaboration and a public ID, with private ones (whose purpose may be secret) reserved just for private use.
>
> Regards,
> Simon
>
> On Wed, 5 May 2021 at 11:42, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote:
>>
>> Hey Folks,
>>
>> We wanted to put out a middle-ground proposal to help guide the discussion on the call tomorrow.
>>
>>
>>
>> A proposal that we have been discussing offline involves reserving a single tag ID for the purpose of construction UEFI PI HOB List structure, and that tag would be used to identify a HOB-specific structure that does leverage UUID based identifier. This will eliminate the burden of having to support UUID as the tag, and this enables projects that require UUID based identifiers for the broad range of HOB structures that need to be produced during the booting of the platform. Once we have a tag for a HOB list, this will enable various HOB producers that can add/extend the HOB list in TF-A code (or even pre-TF-A code), with a HOB consumer for that UUID/GUID on the other side (i.e. whatever the BL33 image is booting on that platform).
>>
>>
>>
>> Essentially, the idea is if someone would like to support HOB structures in a standard way using TF-A, they would wrap it up in a BL_AUX_PARAM/BLOB structure (whatever the group decides) and the way we identify the structure as a HOB list is with this new reserved tag.
>>
>>
>>
>> Hopefully that makes sense and less contentious. Look forward to discuss this further on the call.
>>
>>
>>
>> Thanks,
>>
>> --Harb
>>
>>
>>
>> From: Manish Pandey2 Manish.Pandey2@arm.com
>> Sent: Friday, April 30, 2021 8:14 AM
>> To: François Ozog francois.ozog@linaro.org
>> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> Hi All,
>>
>>
>>
>> Please find invite for next TF-A Tech Forum session to continue our discussions on HOB implementation, feel free to forward it to others.
>>
>>
>>
>> The next TF-A Tech Forum is scheduled for Thu 6th May 2021 16:00 – 17:00 (BST).
>>
>>
>>
>> Agenda:
>>
>> Discussion Session: Static and Dynamic Information Handling in TF-A
>>
>> Lead by Manish Pandey and Madhukar Pappireddy
>>
>> · There is ongoing mailing lists discussion[1] related with adopting a mechanism to pass information through boot stages.
>>
>> The requirement is two-fold:
>>
>> 1. Passing static information(config files)
>>
>> 2. Passing dynamic information (Hob list)
>>
>> In the upcoming TF-A tech forum, we can start with a discussion on dynamic information passing and if time permits, we can cover static information passing. The purpose of the call is to have an open discussion and continue the discussion from the trusted-substrate call[2] done earlier. We would like to understand the various requirements and possible ways to implement it in TF-A in a generalized way so that it can work with other Firmware projects.
>>
>>
>>
>> The two specific item which we would like to discuss are:
>>
>> 1. HOB format: TF-A/u-boot both has an existing bloblist implementation, which uses tag values. Question, can this be enhanced to use hybrid values(Tag and UUID) both?
>>
>> 2. Standardization on Physical register use to pass base of HoB data structure.
>>
>> References:
>>
>> [1] https://lists.trustedfirmware.org/pipermail/tf-a/2021-April/001069.html
>>
>> [2] https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%
>>
>>
>>
>> Thanks
>>
>>
>>
>> Joanna
>>
>>
>>
>> You have been invited to the following event.
>>
>> TF-A Tech Forum
>>
>> When
>>
>> Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time
>>
>> Calendar
>>
>> tf-a@lists.trustedfirmware.org
>>
>> Who
>>
>> •
>>
>> Bill Fletcher- creator
>>
>> •
>>
>> tf-a@lists.trustedfirmware.org
>>
>> more details »
>>
>>
>>
>> We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
>>
>>
>>
>> Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
>>
>>
>>
>> Trusted Firmware is inviting you to a scheduled Zoom meeting.
>>
>>
>>
>> Join Zoom Meeting
>>
>> https://zoom.us/j/9159704974
>>
>>
>>
>> Meeting ID: 915 970 4974
>>
>>
>>
>> One tap mobile
>>
>> +16465588656,,9159704974# US (New York)
>>
>> +16699009128,,9159704974# US (San Jose)
>>
>>
>>
>> Dial by your location
>>
>> +1 646 558 8656 US (New York)
>>
>> +1 669 900 9128 US (San Jose)
>>
>> 877 853 5247 US Toll-free
>>
>> 888 788 0099 US Toll-free
>>
>> Meeting ID: 915 970 4974
>>
>> Find your local number: https://zoom.us/u/ad27hc6t7h
>>
>>
>>
>> ________________________________
>>
>> From: François Ozog francois.ozog@linaro.org
>> Sent: 08 April 2021 16:50
>> To: Manish Pandey2 Manish.Pandey2@arm.com
>> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> Hi
>>
>>
>>
>> here is the meeting recording:
>>
>> https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%z
>>
>>
>>
>> I am really sorry about the confusion related to the meeting time. I have now understood: the Collaborate portal uses a specific calendar which is tied to US/Chicago timezone while the actual Google Calendar is tied to Central Europe timezone. I am going to drop the Collaborate portal and use a shared Google calendar (it should be visible on the trusted-substrate.org page).
>>
>>
>>
>> I'll try to summarize what I learnt and highlight my view on what can be next steps in a future mail.
>>
>>
>>
>> Cheers
>>
>>
>>
>> FF
>>
>>
>>
>> On Thu, 8 Apr 2021 at 13:56, Manish Pandey2 via TF-A tf-a@lists.trustedfirmware.org wrote:
>>
>> Hi,
>>
>>
>>
>> From TF-A project point of view, we prefer to use existing mechanism to pass parameters across boot stages using linked list of tagged elements (as suggested by Julius). It has support for both generic and SiP-specific tags. Having said that, it does not stop partners to introduce new mechanisms suitable for their usecase in platform port initially and later move to generic code if its suitable for other platforms.
>>
>>
>>
>> To start with, Ampere can introduce a platform specific implementation of memory tag(speed/NUMA topology etc) which can be evaluated and discussed for generalization in future. The tag will be populated in BL2 stage and can be forwarded to further stages(and to BL33) by passing the head of list pointer in one of the registers. Initially any register can be used but going forward a standardization will be needed.
>>
>>
>>
>> The U-boot bloblist mentioned by Simon is conceptually similar to what TF-A is using, if there is consensus of using bloblist/taglist then TF-A tag list may be enhanced to take best of both the implementations.
>>
>>
>>
>> One of the potential problems of having structure used in different projects is maintainability, this can be avoided by having a single copy of these structures in TF-A (kept inside "include/export" which intended to be used by other projects.)
>>
>>
>>
>> Regarding usage of either UUID or tag, I echo the sentiments of Simon and Julius to keep it simple and use tag values.
>>
>>
>>
>> Looking forward to having further discussions on zoom call today.
>>
>>
>>
>> Thanks
>>
>> Manish P
>>
>>
>>
>> ________________________________
>>
>> From: TF-A tf-a-bounces@lists.trustedfirmware.org on behalf of Julius Werner via TF-A tf-a@lists.trustedfirmware.org
>> Sent: 25 March 2021 02:43
>> To: Simon Glass sjg@chromium.org
>> Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> Just want to point out that TF-A currently already supports a (very simple) mechanism like this:
>>
>>
>>
>> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>>
>> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>>
>> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>>
>>
>>
>> It's just a linked list of tagged elements. The tag space is split into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31.
>>
>>
>>
>> I would echo Simon's sentiment of keeping this as simple as possible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once.
>>
>>
>>
>> On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A tf-a@lists.trustedfirmware.org wrote:
>>
>> Hi Harb,
>>
>>
>>
>> On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote:
>>
>> Hello Folks,
>>
>> Appreciate the feedback and replies on this. Glad to see that there is interest in this topic.
>>
>>
>>
>> I try to address the comments/feedback from Francois and Simon below….
>>
>>
>>
>> @François Ozog – happy to discuss this on a zoom call. I will make that time slot work, and will be available to attend April 8, 4pm CT.
>>
>>
>>
>> Note that I’m using the term “HOB” here more generically, as there are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases.
>>
>>
>>
>> The whole point here is to provide mechanism to develop firmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM).
>>
>>
>>
>> Keep in mind, in the server/datacenter market segment we are not building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model:
>>
>> “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2, BL31, and *possibly* one or more BL32 instances
>> “Platform” or “board” firmware – in TF-A this may map to BL33 and *possibly* one or more BL32 instances.
>>
>>
>>
>> Even the platform firmware stack could be further fragmented by having multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code.
>>
>>
>>
>> To support a broad range of platform designs with a broad range of memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software.
>>
>>
>>
>> I understand the versatility of DT, but I see two major problems with DT:
>>
>> DT requires more complicated parsing to get properties, and even more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained.
>> DT is probably overkill for this purpose – We really just want a list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob)
>>
>>
>>
>> I think that we should not mix the efforts around DT/ACPI specs with what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs).
>>
>>
>>
>> Frankly, I would personally push back pretty hard on defining SMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls.
>>
>>
>>
>> Please do let me know if you disagree and why. Look forward to discussing on this thread or on the call.
>>
>>
>>
>> @Simon Glass - Thanks for the pointer to bloblist. I briefly reviewed and it seems like a good baseline for what we may be looking for.
>>
>>
>>
>> That being said, I would say that there is some benefit in having some kind of unique identifiers (e.g. UUID or some unique signature) so that we can tie standardized data structures (based on some future TBD specs) to a particular ID. For example, if the TPM driver in BL33 is looking for the TPM structure in the HOB/BOB list, and may not care about the other data blobs. The driver needs a way to identify and locate the blob it cares about.
>>
>>
>>
>> The tag is intended to serve that purpose, although perhaps it should switch from an auto-allocating enum to one with explicit values for each entry and a range for 'local' use.
>>
>>
>>
>> I guess we can achieve this with the tag, but the problem with tag when you have eco-system with a lot of parties doing parallel development, you can end up with tag collisions and folks fighting about who has rights to what tag values. We would need some official process for folks to register tags for whatever new structures we define, or maybe some tag range for vendor specific structures. This comes with a lot of pain and bureaucracy. On the other hand, UUID has been a proven way to make it easy to just define your own blobs with *either* standard or vendor specific structures without worry of ID collisions between vendors.
>>
>>
>>
>> True. I think the pain is overstated, though. In this case I think we actually want something that can be shared between projects and orgs, so some amount of coordination could be considered a benefit. It could just be a github pull request. I find the UUID unfriendly and not just to code size and eyesight! Trying to discover what GUIDs mean or are valid is quite tricky. E.g. see this code:
>>
>>
>>
>> #define FSP_HOB_RESOURCE_OWNER_TSEG_GUID \
>> EFI_GUID(0xd038747c, 0xd00c, 0x4980, \
>> 0xb3, 0x19, 0x49, 0x01, 0x99, 0xa4, 0x7d, 0x55)
>>
>> (etc.)
>>
>>
>>
>> static struct guid_name {
>> efi_guid_t guid;
>> const char *name;
>> } guid_name[] = {
>> { FSP_HOB_RESOURCE_OWNER_TSEG_GUID, "TSEG" },
>> { FSP_HOB_RESOURCE_OWNER_FSP_GUID, "FSP" },
>> { FSP_HOB_RESOURCE_OWNER_SMM_PEI_SMRAM_GUID, "SMM PEI SMRAM" },
>> { FSP_NON_VOLATILE_STORAGE_HOB_GUID, "NVS" },
>> { FSP_VARIABLE_NV_DATA_HOB_GUID, "Variable NVS" },
>> { FSP_GRAPHICS_INFO_HOB_GUID, "Graphics info" },
>> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID1, "PCD database ea" },
>> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID2, "PCD database 9b" },
>>
>> (never figured out what those two are)
>>
>>
>> { FSP_HOB_RESOURCE_OWNER_PEIM_DXE_GUID, "PEIM Init DXE" },
>> { FSP_HOB_RESOURCE_OWNER_ALLOC_STACK_GUID, "Alloc stack" },
>> { FSP_HOB_RESOURCE_OWNER_SMBIOS_MEMORY_GUID, "SMBIOS memory" },
>> { {}, "zero-guid" },
>> {}
>> };
>>
>> static const char *guid_to_name(const efi_guid_t *guid)
>> {
>> struct guid_name *entry;
>>
>> for (entry = guid_name; entry->name; entry++) {
>> if (!guidcmp(guid, &entry->guid))
>> return entry->name;
>> }
>>
>> return NULL;
>> }
>>
>>
>>
>> Believe it or not it took a fair bit of effort to find just that small list, with nearly every one in a separate doc, from memory.
>>
>>
>>
>>
>>
>> We can probably debate whether there is any value in GUID/UUID or not during the call… but again, boblist seems like a reasonable starting point as an alternative to HOB.
>>
>>
>>
>> Indeed. There is certainly value in both approaches.
>>
>>
>>
>> Regards,
>>
>> Simon
>>
>>
>>
>>
>>
>> Thanks,
>>
>> --Harb
>>
>>
>>
>> From: François Ozog francois.ozog@linaro.org
>> Sent: Tuesday, March 23, 2021 10:00 AM
>> To: François Ozog francois.ozog@linaro.org; Ron Minnich rminnich@google.com; Paul Isaac's paul.isaacs@linaro.org
>> Cc: Simon Glass sjg@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> +Ron Minnich +Paul Isaac's
>>
>>
>>
>> Adding Ron and Paul because I think this interface should be also benefiting LinuxBoot efforts.
>>
>>
>>
>> On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A tf-a@lists.trustedfirmware.org wrote:
>>
>> Hi,
>>
>>
>>
>> I propose we cover the topic at the next Trusted Substrate zoom call on April 8th 4pm CET.
>>
>>
>>
>> The agenda:
>>
>> ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, S-EL2, SCP) to adapt hardware description to some runtime conditions.
>>
>> runtime conditions here relates to DRAM size and topology detection, secure DRAM memory carvings, PSCI and SCMI interface publishing.
>>
>>
>>
>> For additional background on existing metadata: UEFI Platform Initialization Specification Version 1.7, 5.5 Resource Descriptor HOB
>>
>> Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY.
>>
>> This HOB lacks memory NUMA attachment or something that could be related to fill SRAT table for ACPI or relevant DT proximity domains.
>>
>> HOB is not consistent accros platforms: some platforms (Arm) lists memory from the booting NUMA node, other platforms (x86) lists all memory from all NUMA nodes. (At least this is the case on the two platforms I tested).
>>
>>
>>
>> There are two proposals to use memory structures from SPL/BLx up to the handover function (as defined in the Device Tree technical report) which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or EDK2.
>>
>> I would propose we also discuss possibility of FF-A interface to actually query information or request actions to be done (this is a model actually used in some SoCs with proprietary SMC calls).
>>
>>
>>
>> Requirements (to be validated):
>>
>> - ACPI and DT hardware descriptions.
>>
>> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2)
>>
>> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, TF-A/LinuxBoot)
>>
>> - at least allows complete DRAM description and "persistent" usage (reserved areas for secure world or other usages)
>>
>> - support secure world device assignment
>>
>>
>>
>> Cheers
>>
>>
>>
>> FF
>>
>>
>>
>>
>>
>> On Mon, 22 Mar 2021 at 19:56, Simon Glass sjg@chromium.org wrote:
>>
>> Hi,
>>
>> Can I suggest using bloblist for this instead? It is lightweight,
>> easier to parse, doesn't have GUIDs and is already used within U-Boot
>> for passing info between SPL/U-Boot, etc.
>>
>> Docs here: https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist
>> Header file describes the format:
>> https://github.com/u-boot/u-boot/blob/master/include/bloblist.h
>>
>> Full set of unit tests:
>> https://github.com/u-boot/u-boot/blob/master/test/bloblist.c
>>
>> Regards,
>> Simon
>>
>> On Mon, 22 Mar 2021 at 23:58, François Ozog francois.ozog@linaro.org wrote:
>> >
>> > +Boot Architecture Mailman List boot-architecture@lists.linaro.org
>> >
>> > standardization is very much welcomed here and need to accommodate a very
>> > diverse set of situations.
>> > For example, TEE OS may need to pass memory reservations to BL33 or
>> > "capture" a device for the secure world.
>> >
>> > I have observed a number of architectures:
>> > 1) pass information from BLx to BLy in the form of a specific object
>> > 2) BLx called by BLy by a platform specific SMC to get information
>> > 3) BLx called by BLy by a platform specific SMC to perform Device Tree
>> > fixups
>> >
>> > I also imagined a standardized "broadcast" FF-A call so that any firmware
>> > element can either provide information or "do something".
>> >
>> > My understanding of your proposal is about standardizing on architecture 1)
>> > with the HOB format.
>> >
>> > The advantage of the HOB is simplicity but it may be difficult to implement
>> > schemes such as pruning a DT because device assignment in the secure world.
>> >
>> > In any case, it looks feasible to have TF-A and OP-TEE complement the list
>> > of HOBs to pass information downstream (the bootflow).
>> >
>> > It would be good to start with building the comprehensive list of
>> > information that need to be conveyed between firmware elements:
>> >
>> > information. | authoritative entity | reporting entity | information
>> > exchanged:
>> > dram | TFA | TFA |
>> > <format to be detailed, NUMA topology to build the SRAT table or DT
>> > equivalent?>
>> > PSCI | SCP | TFA? |
>> > SCMI | SCP or TEE-OS | TFA? TEE-OS?|
>> > secure SRAM | TFA. | TFA. |
>> > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? |
>> > other? | |
>> > |
>> >
>> > Cheers
>> >
>> > FF
>> >
>> >
>> > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A <
>> > tf-a@lists.trustedfirmware.org> wrote:
>> >
>> > > Hello Folks,
>> > >
>> > >
>> > >
>> > > I'm emailing to start an open discussion about the adoption of a concept
>> > > known as "hand-off blocks" or HOB to become a part of the TF-A Firmware
>> > > Framework Architecture (FFA). This is something that is a pretty major
>> > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s
>> > > designed to enable a broad range of highly configurable datacenter
>> > > platforms.
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > What is a HOB (Background)?
>> > >
>> > > ---------------------------
>> > >
>> > > UEFI PI spec describes a particular definition for how HOB may be used for
>> > > transitioning between the PEI and DXE boot phases, which is a good
>> > > reference point for this discussion, but not necessarily the exact solution
>> > > appropriate for TF-A.
>> > >
>> > >
>> > >
>> > > A HOB is simply a dynamically generated data structure passed in between
>> > > two boot phases. This is information that was obtained through discovery
>> > > and needs to be passed forward to the next boot phase *once*, with no API
>> > > needed to call back (e.g. no call back into previous firmware phase is
>> > > needed to fetch this information at run-time - it is simply passed one time
>> > > during boot).
>> > >
>> > >
>> > >
>> > > There may be one or more HOBs passed in between boot phases. If there are
>> > > more than one HOB that needs to be passed, this can be in a form of a "HOB
>> > > table", which (for example) could be a UUID indexed array of pointers to
>> > > HOB structures, used to locate a HOB of interest (based on UUID). In such
>> > > cases, instead of passing a single HOB, the boot phases may rely on passing
>> > > the pointer to the HOB table.
>> > >
>> > >
>> > >
>> > > This has been extremely useful concept to employ on highly configurable
>> > > systems that must rely on flexible discovery mechanisms to initialize and
>> > > boot the system. This is especially helpful when you have multiple
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > Why do we need HOBs in TF-A?:
>> > >
>> > > -----------------------------
>> > >
>> > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server SoC in
>> > > a way that is SoC specific *but* platform agnostic. This means that a
>> > > single ARM SoC that a SiP may deliver to customers may provide a single
>> > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a broad
>> > > range of platform designs and configurations in order to boot a platform
>> > > specific firmware (e.g. BL33 and possibly even BL32 code). In order to
>> > > achieve this, the platform configuration must be *discovered* instead of
>> > > statically compiled as it is today in TF-A via device tree based
>> > > enumeration. The mechanisms of discovery may differ broadly depending on
>> > > the relevant industry standard, or in some cases may have rely on SiP
>> > > specific discovery flows.
>> > >
>> > >
>> > >
>> > > For example: On server systems that support a broad range DIMM memory
>> > > population/topologies, all the necessary information required to boot is
>> > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over an
>> > > I2C bus. Leveraging the SPD bus, may platform variants could be supported
>> > > with a single TF-A binary. Not only is this information required to
>> > > initialize memory in early boot phases (e.g. BL2), the subsequent boot
>> > > phases will also need this SPD info to construct a system physical address
>> > > map and properly initialize the MMU based on the memory present, and where
>> > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) may
>> > > need to generate standard firmware tables to the operating systems, such as
>> > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. SLIT,
>> > > SRAT, even NFIT if NVDIMM's are present).
>> > >
>> > >
>> > >
>> > > In short, it all starts with a standardized or vendor specific discovery
>> > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of
>> > > information to the next boot stages (e.g. BL31/BL32/BL33).
>> > >
>> > >
>> > >
>> > > Today, every HOB may be a vendor specific structure, but in the future
>> > > there may be benefit of defining standard HOBs. This may be useful for
>> > > memory discovery, passing the system physical address map, enabling TPM
>> > > measured boot, and potentially many other common HOB use-cases.
>> > >
>> > >
>> > >
>> > > It would be extremely beneficial to the datacenter market segment if the
>> > > TF-A community would adopt this concept of information passing between all
>> > > boot phases as opposed to rely solely on device tree enumeration. This is
>> > > not intended to replace device tree, rather intended as an alternative way
>> > > to describe the info that must be discovered and dynamically generated.
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > Conclusion:
>> > >
>> > > -----------
>> > >
>> > > We are proposing that the TF-A community begin pursuing the adoption of
>> > > HOBs as a mechanism used for information exchange between each boot stage
>> > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term we
>> > > want to explore standardizing some HOB structures for the BL33 phase (e.g.
>> > > UEFI HOB structures), but initially would like to agree on this being a
>> > > useful mechanism used to pass information between each boot stage.
>> > >
>> > >
>> > >
>> > > Thanks,
>> > >
>> > > --Harb
>> > >
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > --
>> > > TF-A mailing list
>> > > TF-A@lists.trustedfirmware.org
>> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>> > >
>> >
>> >
>> > --
>> > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group*
>> > T: +33.67221.6485
>> > francois.ozog@linaro.org | Skype: ffozog
>> > _______________________________________________
>> > boot-architecture mailing list
>> > boot-architecture@lists.linaro.org
>> > https://lists.linaro.org/mailman/listinfo/boot-architecture
>>
>>
>>
>>
>> --
>>
>> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group
>>
>> T: +33.67221.6485
>> francois.ozog@linaro.org | Skype: ffozog
>>
>>
>>
>> --
>> TF-A mailing list
>> TF-A@lists.trustedfirmware.org
>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>>
>>
>>
>>
>> --
>>
>> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group
>>
>> T: +33.67221.6485
>> francois.ozog@linaro.org | Skype: ffozog
>>
>>
>>
>> --
>> TF-A mailing list
>> TF-A@lists.trustedfirmware.org
>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>>
>> --
>> TF-A mailing list
>> TF-A@lists.trustedfirmware.org
>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>>
>>
>>
>>
>> --
>>
>> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group
>>
>> T: +33.67221.6485
>> francois.ozog@linaro.org | Skype: ffozog
>>
>>
>
> --
> TF-A mailing list
> TF-A@lists.trustedfirmware.org
> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
--
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+ TF-A list that got dropped (again)!
Joanna
From: Joanna Farley Joanna.Farley@arm.com Date: Wednesday, 2 June 2021 at 15:29 To: Madhukar Pappireddy Madhukar.Pappireddy@arm.com, Okash Khawaja okash.khawaja@gmail.com, Simon Glass sjg@chromium.org Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com, Boot Architecture Mailman List boot-architecture@lists.linaro.org, Ed Stuber edstuber@amperecomputing.com, Arjun Khare akhare@amperecomputing.com, U-Boot Mailing List u-boot@lists.denx.de, Paul Isaac's paul.isaacs@linaro.org, Ron Minnich rminnich@google.com, Moe Ammar moe@amperecomputing.com Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi Everyone,
The Manish Pandy and Madhukar Pappireddy of the TF-A team are planning to host another TF-A Tech Forum this Thursday to continue the live discussion.
Here is their agenda:
On tech forum this week, we would like to continue discussions on HOB list design.
The topics which we would like to cover is
1. Evaluate different proposals of passing information through boot phases.
2. If we don't get an agreement on one solution fit for all then we would try to get consensus for Infra segment platform(to solve original problem mentioned by Harb)
3. Try to get an agreement on size of tags and how "hybrid and tag only" HOB list can co-exist together?
Details of the call are:
======================
TF-A Tech Forum
When Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time
Calendar tf-a@lists.trustedfirmware.org
Who • Bill Fletcher- creator
• tf-a@lists.trustedfirmware.org
We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
Trusted Firmware is inviting you to a scheduled Zoom meeting.
Join Zoom Meeting
Meeting ID: 915 970 4974
One tap mobile
+16465588656,,9159704974# US (New York)
+16699009128,,9159704974# US (San Jose)
Dial by your location
+1 646 558 8656 US (New York)
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Meeting ID: 915 970 4974
Find your local number: https://zoom.us/u/ad27hc6t7h
================
Joanna
On 19/05/2021, 03:50, "Madhukar Pappireddy" Madhukar.Pappireddy@arm.com wrote:
Attached slides presented by Manish in the TF-A tech forum.
-----Original Message-----
From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Madhukar Pappireddy via TF-A
Sent: Tuesday, May 18, 2021 8:59 PM
To: Joanna Farley Joanna.Farley@arm.com; Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org
Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; tf-a@lists.trustedfirmware.org; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi,
I tried to summarize the discussions in the previous TF-A tech forum regarding the proposal to adopt Hand-off Blocks (HOBs) for passing information along the boot chain. I am certain I could not capture all suggestions/concerns brought up during the call. I apologize if I missed and/or misinterpreted any comments and would appreciate it if everyone could share their thoughts in response to this email thread.
The idea is to share information to other boot phases:
> Dynamic information: Created during runtime. Shared in the form of a chain of blobs(built as a linked list of C structure objects i.e., HOB list).
> Static information: Known at compile time. Historically, shared through the use of Device Tree/ACPI tables
Both the above requirements are common in many ecosystems and need to co-exist.
There are broadly 3 problems to solve:
1. Format of HOB structures: It looks like the consensus is that we could use existing mechanisms for this (BL_AUX_PARAM in TF-A or bloblist in u-boot).
2. Identification of HOB list entries: There is a debate about whether tags would suffice or if the HOB list producer and consumer would depend on UUID/GUIDs for identifying a specific HOB structure. Another suggestion was to use a hybrid approach. Reserve a single tag ID for identifying/constructing a HOB structure that further leverages UUID based identifier. This way, the generic HOB list doesn't need to support UUIDs and can work with tags.
3. The design contract for the static interface between two boot phases: The problem at hand is whether to pass a pointer to a HOB list or a device tree blob through the general-purpose registers for configuration hand-off between two boot phases. Some proposals that came up:
> Proposal 1: Always pass a pointer to the device tree blob through the GP register and capture the pointer to the HOB list as a property of a node that is uniquely identifiable by the downstream boot phase. This needs to define a device tree binding such that producer and consumer agree on the information passed.
> Proposal 2: Pass a pointer to a generic container through the GP register that can be interpreted appropriately by both boot loaders(i.e., producer and consumer of the boot info). This container can either be a dtb or a HOB list which can be simply inferred by checking for a magic header that indicates if the buffer appears to be a flattened device tree.
> One another concern that was brought up offline is to make sure we don't break current design contracts between various boot loader phases in TF-A. Many of the general-purpose registers have a designated purpose such as to share configurations between BL images( such as firmware config dtb, SoC config dtb, Non trusted firmware config dtb, memory layout, entry point info, etc.).
If I am not mistaken, a single design may not fit the needs of every segment(client, Infra, embedded) and the forum is open to solutions tailored for individual segments. Joanna will be sending a follow up email with more information about future TF-A tech forums that serves as a platform for further discussions.
Thanks,
Madhukar
-----Original Message-----
From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Joanna Farley via TF-A
Sent: Sunday, May 16, 2021 5:19 AM
To: Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org
Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Apologies I failed with the recording. Manish/Madhu will reply early next week with the slides and some notes to help with a follow up session which we hope to hold this Thursday. Invite and agenda will also be sent out early next week.
Thanks
Joanna
On 14/05/2021, 13:30, "TF-A on behalf of Okash Khawaja via TF-A" <tf-a-bounces@lists.trustedfirmware.org on behalf of tf-a@lists.trustedfirmware.org> wrote:
Hi,
Do we have slides and video from last week's discussion?
Thanks,
Okash
On Wed, May 5, 2021 at 11:52 PM Simon Glass via TF-A
tf-a@lists.trustedfirmware.org wrote:
>
> Hi Harb,
>
> Thanks for the idea. I am still not completely sure what benefit UUID provides to an open project. I'd like to propose something different, more in the spirit of open collaboration. I also worry that the word 'standard' seems to be a synonym for UUIDs, UEFI, etc., i.e. enabling/preferring closed-source firmware and the continued decline of open-source projects. It really should not be.
>
> So I suggest: Use simple integer IDs and reserve some area for 'private' use. If you want to collaborate across projects outside your company, you either need to allocate a 'public' ID or agree privately between the parties which private ID to use.
>
> This means that the default and easiest option is for collaboration and a public ID, with private ones (whose purpose may be secret) reserved just for private use.
>
> Regards,
> Simon
>
> On Wed, 5 May 2021 at 11:42, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote:
>>
>> Hey Folks,
>>
>> We wanted to put out a middle-ground proposal to help guide the discussion on the call tomorrow.
>>
>>
>>
>> A proposal that we have been discussing offline involves reserving a single tag ID for the purpose of construction UEFI PI HOB List structure, and that tag would be used to identify a HOB-specific structure that does leverage UUID based identifier. This will eliminate the burden of having to support UUID as the tag, and this enables projects that require UUID based identifiers for the broad range of HOB structures that need to be produced during the booting of the platform. Once we have a tag for a HOB list, this will enable various HOB producers that can add/extend the HOB list in TF-A code (or even pre-TF-A code), with a HOB consumer for that UUID/GUID on the other side (i.e. whatever the BL33 image is booting on that platform).
>>
>>
>>
>> Essentially, the idea is if someone would like to support HOB structures in a standard way using TF-A, they would wrap it up in a BL_AUX_PARAM/BLOB structure (whatever the group decides) and the way we identify the structure as a HOB list is with this new reserved tag.
>>
>>
>>
>> Hopefully that makes sense and less contentious. Look forward to discuss this further on the call.
>>
>>
>>
>> Thanks,
>>
>> --Harb
>>
>>
>>
>> From: Manish Pandey2 Manish.Pandey2@arm.com
>> Sent: Friday, April 30, 2021 8:14 AM
>> To: François Ozog francois.ozog@linaro.org
>> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> Hi All,
>>
>>
>>
>> Please find invite for next TF-A Tech Forum session to continue our discussions on HOB implementation, feel free to forward it to others.
>>
>>
>>
>> The next TF-A Tech Forum is scheduled for Thu 6th May 2021 16:00 – 17:00 (BST).
>>
>>
>>
>> Agenda:
>>
>> Discussion Session: Static and Dynamic Information Handling in TF-A
>>
>> Lead by Manish Pandey and Madhukar Pappireddy
>>
>> · There is ongoing mailing lists discussion[1] related with adopting a mechanism to pass information through boot stages.
>>
>> The requirement is two-fold:
>>
>> 1. Passing static information(config files)
>>
>> 2. Passing dynamic information (Hob list)
>>
>> In the upcoming TF-A tech forum, we can start with a discussion on dynamic information passing and if time permits, we can cover static information passing. The purpose of the call is to have an open discussion and continue the discussion from the trusted-substrate call[2] done earlier. We would like to understand the various requirements and possible ways to implement it in TF-A in a generalized way so that it can work with other Firmware projects.
>>
>>
>>
>> The two specific item which we would like to discuss are:
>>
>> 1. HOB format: TF-A/u-boot both has an existing bloblist implementation, which uses tag values. Question, can this be enhanced to use hybrid values(Tag and UUID) both?
>>
>> 2. Standardization on Physical register use to pass base of HoB data structure.
>>
>> References:
>>
>> [1] https://lists.trustedfirmware.org/pipermail/tf-a/2021-April/001069.html
>>
>> [2] https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%
>>
>>
>>
>> Thanks
>>
>>
>>
>> Joanna
>>
>>
>>
>> You have been invited to the following event.
>>
>> TF-A Tech Forum
>>
>> When
>>
>> Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time
>>
>> Calendar
>>
>> tf-a@lists.trustedfirmware.org
>>
>> Who
>>
>> •
>>
>> Bill Fletcher- creator
>>
>> •
>>
>> tf-a@lists.trustedfirmware.org
>>
>> more details »
>>
>>
>>
>> We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
>>
>>
>>
>> Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
>>
>>
>>
>> Trusted Firmware is inviting you to a scheduled Zoom meeting.
>>
>>
>>
>> Join Zoom Meeting
>>
>> https://zoom.us/j/9159704974
>>
>>
>>
>> Meeting ID: 915 970 4974
>>
>>
>>
>> One tap mobile
>>
>> +16465588656,,9159704974# US (New York)
>>
>> +16699009128,,9159704974# US (San Jose)
>>
>>
>>
>> Dial by your location
>>
>> +1 646 558 8656 US (New York)
>>
>> +1 669 900 9128 US (San Jose)
>>
>> 877 853 5247 US Toll-free
>>
>> 888 788 0099 US Toll-free
>>
>> Meeting ID: 915 970 4974
>>
>> Find your local number: https://zoom.us/u/ad27hc6t7h
>>
>>
>>
>> ________________________________
>>
>> From: François Ozog francois.ozog@linaro.org
>> Sent: 08 April 2021 16:50
>> To: Manish Pandey2 Manish.Pandey2@arm.com
>> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> Hi
>>
>>
>>
>> here is the meeting recording:
>>
>> https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%z
>>
>>
>>
>> I am really sorry about the confusion related to the meeting time. I have now understood: the Collaborate portal uses a specific calendar which is tied to US/Chicago timezone while the actual Google Calendar is tied to Central Europe timezone. I am going to drop the Collaborate portal and use a shared Google calendar (it should be visible on the trusted-substrate.org page).
>>
>>
>>
>> I'll try to summarize what I learnt and highlight my view on what can be next steps in a future mail.
>>
>>
>>
>> Cheers
>>
>>
>>
>> FF
>>
>>
>>
>> On Thu, 8 Apr 2021 at 13:56, Manish Pandey2 via TF-A tf-a@lists.trustedfirmware.org wrote:
>>
>> Hi,
>>
>>
>>
>> From TF-A project point of view, we prefer to use existing mechanism to pass parameters across boot stages using linked list of tagged elements (as suggested by Julius). It has support for both generic and SiP-specific tags. Having said that, it does not stop partners to introduce new mechanisms suitable for their usecase in platform port initially and later move to generic code if its suitable for other platforms.
>>
>>
>>
>> To start with, Ampere can introduce a platform specific implementation of memory tag(speed/NUMA topology etc) which can be evaluated and discussed for generalization in future. The tag will be populated in BL2 stage and can be forwarded to further stages(and to BL33) by passing the head of list pointer in one of the registers. Initially any register can be used but going forward a standardization will be needed.
>>
>>
>>
>> The U-boot bloblist mentioned by Simon is conceptually similar to what TF-A is using, if there is consensus of using bloblist/taglist then TF-A tag list may be enhanced to take best of both the implementations.
>>
>>
>>
>> One of the potential problems of having structure used in different projects is maintainability, this can be avoided by having a single copy of these structures in TF-A (kept inside "include/export" which intended to be used by other projects.)
>>
>>
>>
>> Regarding usage of either UUID or tag, I echo the sentiments of Simon and Julius to keep it simple and use tag values.
>>
>>
>>
>> Looking forward to having further discussions on zoom call today.
>>
>>
>>
>> Thanks
>>
>> Manish P
>>
>>
>>
>> ________________________________
>>
>> From: TF-A tf-a-bounces@lists.trustedfirmware.org on behalf of Julius Werner via TF-A tf-a@lists.trustedfirmware.org
>> Sent: 25 March 2021 02:43
>> To: Simon Glass sjg@chromium.org
>> Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> Just want to point out that TF-A currently already supports a (very simple) mechanism like this:
>>
>>
>>
>> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>>
>> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>>
>> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>>
>>
>>
>> It's just a linked list of tagged elements. The tag space is split into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31.
>>
>>
>>
>> I would echo Simon's sentiment of keeping this as simple as possible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once.
>>
>>
>>
>> On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A tf-a@lists.trustedfirmware.org wrote:
>>
>> Hi Harb,
>>
>>
>>
>> On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote:
>>
>> Hello Folks,
>>
>> Appreciate the feedback and replies on this. Glad to see that there is interest in this topic.
>>
>>
>>
>> I try to address the comments/feedback from Francois and Simon below….
>>
>>
>>
>> @François Ozog – happy to discuss this on a zoom call. I will make that time slot work, and will be available to attend April 8, 4pm CT.
>>
>>
>>
>> Note that I’m using the term “HOB” here more generically, as there are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases.
>>
>>
>>
>> The whole point here is to provide mechanism to develop firmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM).
>>
>>
>>
>> Keep in mind, in the server/datacenter market segment we are not building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model:
>>
>> “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2, BL31, and *possibly* one or more BL32 instances
>> “Platform” or “board” firmware – in TF-A this may map to BL33 and *possibly* one or more BL32 instances.
>>
>>
>>
>> Even the platform firmware stack could be further fragmented by having multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code.
>>
>>
>>
>> To support a broad range of platform designs with a broad range of memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software.
>>
>>
>>
>> I understand the versatility of DT, but I see two major problems with DT:
>>
>> DT requires more complicated parsing to get properties, and even more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained.
>> DT is probably overkill for this purpose – We really just want a list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob)
>>
>>
>>
>> I think that we should not mix the efforts around DT/ACPI specs with what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs).
>>
>>
>>
>> Frankly, I would personally push back pretty hard on defining SMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls.
>>
>>
>>
>> Please do let me know if you disagree and why. Look forward to discussing on this thread or on the call.
>>
>>
>>
>> @Simon Glass - Thanks for the pointer to bloblist. I briefly reviewed and it seems like a good baseline for what we may be looking for.
>>
>>
>>
>> That being said, I would say that there is some benefit in having some kind of unique identifiers (e.g. UUID or some unique signature) so that we can tie standardized data structures (based on some future TBD specs) to a particular ID. For example, if the TPM driver in BL33 is looking for the TPM structure in the HOB/BOB list, and may not care about the other data blobs. The driver needs a way to identify and locate the blob it cares about.
>>
>>
>>
>> The tag is intended to serve that purpose, although perhaps it should switch from an auto-allocating enum to one with explicit values for each entry and a range for 'local' use.
>>
>>
>>
>> I guess we can achieve this with the tag, but the problem with tag when you have eco-system with a lot of parties doing parallel development, you can end up with tag collisions and folks fighting about who has rights to what tag values. We would need some official process for folks to register tags for whatever new structures we define, or maybe some tag range for vendor specific structures. This comes with a lot of pain and bureaucracy. On the other hand, UUID has been a proven way to make it easy to just define your own blobs with *either* standard or vendor specific structures without worry of ID collisions between vendors.
>>
>>
>>
>> True. I think the pain is overstated, though. In this case I think we actually want something that can be shared between projects and orgs, so some amount of coordination could be considered a benefit. It could just be a github pull request. I find the UUID unfriendly and not just to code size and eyesight! Trying to discover what GUIDs mean or are valid is quite tricky. E.g. see this code:
>>
>>
>>
>> #define FSP_HOB_RESOURCE_OWNER_TSEG_GUID \
>> EFI_GUID(0xd038747c, 0xd00c, 0x4980, \
>> 0xb3, 0x19, 0x49, 0x01, 0x99, 0xa4, 0x7d, 0x55)
>>
>> (etc.)
>>
>>
>>
>> static struct guid_name {
>> efi_guid_t guid;
>> const char *name;
>> } guid_name[] = {
>> { FSP_HOB_RESOURCE_OWNER_TSEG_GUID, "TSEG" },
>> { FSP_HOB_RESOURCE_OWNER_FSP_GUID, "FSP" },
>> { FSP_HOB_RESOURCE_OWNER_SMM_PEI_SMRAM_GUID, "SMM PEI SMRAM" },
>> { FSP_NON_VOLATILE_STORAGE_HOB_GUID, "NVS" },
>> { FSP_VARIABLE_NV_DATA_HOB_GUID, "Variable NVS" },
>> { FSP_GRAPHICS_INFO_HOB_GUID, "Graphics info" },
>> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID1, "PCD database ea" },
>> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID2, "PCD database 9b" },
>>
>> (never figured out what those two are)
>>
>>
>> { FSP_HOB_RESOURCE_OWNER_PEIM_DXE_GUID, "PEIM Init DXE" },
>> { FSP_HOB_RESOURCE_OWNER_ALLOC_STACK_GUID, "Alloc stack" },
>> { FSP_HOB_RESOURCE_OWNER_SMBIOS_MEMORY_GUID, "SMBIOS memory" },
>> { {}, "zero-guid" },
>> {}
>> };
>>
>> static const char *guid_to_name(const efi_guid_t *guid)
>> {
>> struct guid_name *entry;
>>
>> for (entry = guid_name; entry->name; entry++) {
>> if (!guidcmp(guid, &entry->guid))
>> return entry->name;
>> }
>>
>> return NULL;
>> }
>>
>>
>>
>> Believe it or not it took a fair bit of effort to find just that small list, with nearly every one in a separate doc, from memory.
>>
>>
>>
>>
>>
>> We can probably debate whether there is any value in GUID/UUID or not during the call… but again, boblist seems like a reasonable starting point as an alternative to HOB.
>>
>>
>>
>> Indeed. There is certainly value in both approaches.
>>
>>
>>
>> Regards,
>>
>> Simon
>>
>>
>>
>>
>>
>> Thanks,
>>
>> --Harb
>>
>>
>>
>> From: François Ozog francois.ozog@linaro.org
>> Sent: Tuesday, March 23, 2021 10:00 AM
>> To: François Ozog francois.ozog@linaro.org; Ron Minnich rminnich@google.com; Paul Isaac's paul.isaacs@linaro.org
>> Cc: Simon Glass sjg@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> +Ron Minnich +Paul Isaac's
>>
>>
>>
>> Adding Ron and Paul because I think this interface should be also benefiting LinuxBoot efforts.
>>
>>
>>
>> On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A tf-a@lists.trustedfirmware.org wrote:
>>
>> Hi,
>>
>>
>>
>> I propose we cover the topic at the next Trusted Substrate zoom call on April 8th 4pm CET.
>>
>>
>>
>> The agenda:
>>
>> ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, S-EL2, SCP) to adapt hardware description to some runtime conditions.
>>
>> runtime conditions here relates to DRAM size and topology detection, secure DRAM memory carvings, PSCI and SCMI interface publishing.
>>
>>
>>
>> For additional background on existing metadata: UEFI Platform Initialization Specification Version 1.7, 5.5 Resource Descriptor HOB
>>
>> Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY.
>>
>> This HOB lacks memory NUMA attachment or something that could be related to fill SRAT table for ACPI or relevant DT proximity domains.
>>
>> HOB is not consistent accros platforms: some platforms (Arm) lists memory from the booting NUMA node, other platforms (x86) lists all memory from all NUMA nodes. (At least this is the case on the two platforms I tested).
>>
>>
>>
>> There are two proposals to use memory structures from SPL/BLx up to the handover function (as defined in the Device Tree technical report) which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or EDK2.
>>
>> I would propose we also discuss possibility of FF-A interface to actually query information or request actions to be done (this is a model actually used in some SoCs with proprietary SMC calls).
>>
>>
>>
>> Requirements (to be validated):
>>
>> - ACPI and DT hardware descriptions.
>>
>> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2)
>>
>> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, TF-A/LinuxBoot)
>>
>> - at least allows complete DRAM description and "persistent" usage (reserved areas for secure world or other usages)
>>
>> - support secure world device assignment
>>
>>
>>
>> Cheers
>>
>>
>>
>> FF
>>
>>
>>
>>
>>
>> On Mon, 22 Mar 2021 at 19:56, Simon Glass sjg@chromium.org wrote:
>>
>> Hi,
>>
>> Can I suggest using bloblist for this instead? It is lightweight,
>> easier to parse, doesn't have GUIDs and is already used within U-Boot
>> for passing info between SPL/U-Boot, etc.
>>
>> Docs here: https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist
>> Header file describes the format:
>> https://github.com/u-boot/u-boot/blob/master/include/bloblist.h
>>
>> Full set of unit tests:
>> https://github.com/u-boot/u-boot/blob/master/test/bloblist.c
>>
>> Regards,
>> Simon
>>
>> On Mon, 22 Mar 2021 at 23:58, François Ozog francois.ozog@linaro.org wrote:
>> >
>> > +Boot Architecture Mailman List boot-architecture@lists.linaro.org
>> >
>> > standardization is very much welcomed here and need to accommodate a very
>> > diverse set of situations.
>> > For example, TEE OS may need to pass memory reservations to BL33 or
>> > "capture" a device for the secure world.
>> >
>> > I have observed a number of architectures:
>> > 1) pass information from BLx to BLy in the form of a specific object
>> > 2) BLx called by BLy by a platform specific SMC to get information
>> > 3) BLx called by BLy by a platform specific SMC to perform Device Tree
>> > fixups
>> >
>> > I also imagined a standardized "broadcast" FF-A call so that any firmware
>> > element can either provide information or "do something".
>> >
>> > My understanding of your proposal is about standardizing on architecture 1)
>> > with the HOB format.
>> >
>> > The advantage of the HOB is simplicity but it may be difficult to implement
>> > schemes such as pruning a DT because device assignment in the secure world.
>> >
>> > In any case, it looks feasible to have TF-A and OP-TEE complement the list
>> > of HOBs to pass information downstream (the bootflow).
>> >
>> > It would be good to start with building the comprehensive list of
>> > information that need to be conveyed between firmware elements:
>> >
>> > information. | authoritative entity | reporting entity | information
>> > exchanged:
>> > dram | TFA | TFA |
>> > <format to be detailed, NUMA topology to build the SRAT table or DT
>> > equivalent?>
>> > PSCI | SCP | TFA? |
>> > SCMI | SCP or TEE-OS | TFA? TEE-OS?|
>> > secure SRAM | TFA. | TFA. |
>> > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? |
>> > other? | |
>> > |
>> >
>> > Cheers
>> >
>> > FF
>> >
>> >
>> > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A <
>> > tf-a@lists.trustedfirmware.org> wrote:
>> >
>> > > Hello Folks,
>> > >
>> > >
>> > >
>> > > I'm emailing to start an open discussion about the adoption of a concept
>> > > known as "hand-off blocks" or HOB to become a part of the TF-A Firmware
>> > > Framework Architecture (FFA). This is something that is a pretty major
>> > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s
>> > > designed to enable a broad range of highly configurable datacenter
>> > > platforms.
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > What is a HOB (Background)?
>> > >
>> > > ---------------------------
>> > >
>> > > UEFI PI spec describes a particular definition for how HOB may be used for
>> > > transitioning between the PEI and DXE boot phases, which is a good
>> > > reference point for this discussion, but not necessarily the exact solution
>> > > appropriate for TF-A.
>> > >
>> > >
>> > >
>> > > A HOB is simply a dynamically generated data structure passed in between
>> > > two boot phases. This is information that was obtained through discovery
>> > > and needs to be passed forward to the next boot phase *once*, with no API
>> > > needed to call back (e.g. no call back into previous firmware phase is
>> > > needed to fetch this information at run-time - it is simply passed one time
>> > > during boot).
>> > >
>> > >
>> > >
>> > > There may be one or more HOBs passed in between boot phases. If there are
>> > > more than one HOB that needs to be passed, this can be in a form of a "HOB
>> > > table", which (for example) could be a UUID indexed array of pointers to
>> > > HOB structures, used to locate a HOB of interest (based on UUID). In such
>> > > cases, instead of passing a single HOB, the boot phases may rely on passing
>> > > the pointer to the HOB table.
>> > >
>> > >
>> > >
>> > > This has been extremely useful concept to employ on highly configurable
>> > > systems that must rely on flexible discovery mechanisms to initialize and
>> > > boot the system. This is especially helpful when you have multiple
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > Why do we need HOBs in TF-A?:
>> > >
>> > > -----------------------------
>> > >
>> > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server SoC in
>> > > a way that is SoC specific *but* platform agnostic. This means that a
>> > > single ARM SoC that a SiP may deliver to customers may provide a single
>> > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a broad
>> > > range of platform designs and configurations in order to boot a platform
>> > > specific firmware (e.g. BL33 and possibly even BL32 code). In order to
>> > > achieve this, the platform configuration must be *discovered* instead of
>> > > statically compiled as it is today in TF-A via device tree based
>> > > enumeration. The mechanisms of discovery may differ broadly depending on
>> > > the relevant industry standard, or in some cases may have rely on SiP
>> > > specific discovery flows.
>> > >
>> > >
>> > >
>> > > For example: On server systems that support a broad range DIMM memory
>> > > population/topologies, all the necessary information required to boot is
>> > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over an
>> > > I2C bus. Leveraging the SPD bus, may platform variants could be supported
>> > > with a single TF-A binary. Not only is this information required to
>> > > initialize memory in early boot phases (e.g. BL2), the subsequent boot
>> > > phases will also need this SPD info to construct a system physical address
>> > > map and properly initialize the MMU based on the memory present, and where
>> > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) may
>> > > need to generate standard firmware tables to the operating systems, such as
>> > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. SLIT,
>> > > SRAT, even NFIT if NVDIMM's are present).
>> > >
>> > >
>> > >
>> > > In short, it all starts with a standardized or vendor specific discovery
>> > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of
>> > > information to the next boot stages (e.g. BL31/BL32/BL33).
>> > >
>> > >
>> > >
>> > > Today, every HOB may be a vendor specific structure, but in the future
>> > > there may be benefit of defining standard HOBs. This may be useful for
>> > > memory discovery, passing the system physical address map, enabling TPM
>> > > measured boot, and potentially many other common HOB use-cases.
>> > >
>> > >
>> > >
>> > > It would be extremely beneficial to the datacenter market segment if the
>> > > TF-A community would adopt this concept of information passing between all
>> > > boot phases as opposed to rely solely on device tree enumeration. This is
>> > > not intended to replace device tree, rather intended as an alternative way
>> > > to describe the info that must be discovered and dynamically generated.
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > Conclusion:
>> > >
>> > > -----------
>> > >
>> > > We are proposing that the TF-A community begin pursuing the adoption of
>> > > HOBs as a mechanism used for information exchange between each boot stage
>> > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term we
>> > > want to explore standardizing some HOB structures for the BL33 phase (e.g.
>> > > UEFI HOB structures), but initially would like to agree on this being a
>> > > useful mechanism used to pass information between each boot stage.
>> > >
>> > >
>> > >
>> > > Thanks,
>> > >
>> > > --Harb
>> > >
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > --
>> > > TF-A mailing list
>> > > TF-A@lists.trustedfirmware.org
>> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>> > >
>> >
>> >
>> > --
>> > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group*
>> > T: +33.67221.6485
>> > francois.ozog@linaro.org | Skype: ffozog
>> > _______________________________________________
>> > boot-architecture mailing list
>> > boot-architecture@lists.linaro.org
>> > https://lists.linaro.org/mailman/listinfo/boot-architecture
>>
>>
>>
>>
>> --
>>
>> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group
>>
>> T: +33.67221.6485
>> francois.ozog@linaro.org | Skype: ffozog
>>
>>
>>
>> --
>> TF-A mailing list
>> TF-A@lists.trustedfirmware.org
>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>>
>>
>>
>>
>> --
>>
>> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group
>>
>> T: +33.67221.6485
>> francois.ozog@linaro.org | Skype: ffozog
>>
>>
>>
>> --
>> TF-A mailing list
>> TF-A@lists.trustedfirmware.org
>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>>
>> --
>> TF-A mailing list
>> TF-A@lists.trustedfirmware.org
>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>>
>>
>>
>>
>> --
>>
>> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group
>>
>> T: +33.67221.6485
>> francois.ozog@linaro.org | Skype: ffozog
>>
>>
>
> --
> TF-A mailing list
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> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
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Hi Everyone,
I have tried to conclude the discussions we had in two of the TF-A tech forum sessions and on mailing list.
The problem we are trying to solve is already solved in different projects in different ways, the purpose of these discussions was to come up with a standard way which can be adopted widely. Considering that many Firmware projects are not DT aware its better to avoid its usage and use simple C structures for wider acceptance. Based on the discussions following design came up as most acceptable solution
* Use list of pre-defined C data structures(blobs) to pass information, let's call it bloblist * Only bootloaders stages will participate * Blobs will be identified by either tags or UUIDs * Pass pointer to the bloblist head through x0 * Existing usage of x0 will be translated into a blob
Going forward we would provide core changes to demonstrate this design on various TF-A boundries, BL1<->BL2, BL2<->BL31 and BL31<->BL33(only BL31 part)
Please share your thoughts if you disagree to the proposed solution.
Also, refer to attached slide deck which was presented during last tech forum session on 3rd june, it also captures the points discussed during meeting and next steps for implementing it in TF-A.
Thanks Manish Pandey ________________________________ From: Joanna Farley Joanna.Farley@arm.com Sent: 02 June 2021 16:26 To: Madhukar Pappireddy Madhukar.Pappireddy@arm.com; Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; Manish Pandey2 Manish.Pandey2@arm.com Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
+ TF-A list that got dropped (again)!
Joanna
From: Joanna Farley Joanna.Farley@arm.com Date: Wednesday, 2 June 2021 at 15:29 To: Madhukar Pappireddy Madhukar.Pappireddy@arm.com, Okash Khawaja okash.khawaja@gmail.com, Simon Glass sjg@chromium.org Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com, Boot Architecture Mailman List boot-architecture@lists.linaro.org, Ed Stuber edstuber@amperecomputing.com, Arjun Khare akhare@amperecomputing.com, U-Boot Mailing List u-boot@lists.denx.de, Paul Isaac's paul.isaacs@linaro.org, Ron Minnich rminnich@google.com, Moe Ammar moe@amperecomputing.com Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi Everyone,
The Manish Pandy and Madhukar Pappireddy of the TF-A team are planning to host another TF-A Tech Forum this Thursday to continue the live discussion.
Here is their agenda:
On tech forum this week, we would like to continue discussions on HOB list design.
The topics which we would like to cover is
1. Evaluate different proposals of passing information through boot phases.
2. If we don't get an agreement on one solution fit for all then we would try to get consensus for Infra segment platform(to solve original problem mentioned by Harb)
3. Try to get an agreement on size of tags and how "hybrid and tag only" HOB list can co-exist together?
Details of the call are:
======================
TF-A Tech Forum
When Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time
Calendar tf-a@lists.trustedfirmware.org
Who • Bill Fletcher- creator
• tf-a@lists.trustedfirmware.org
We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
Trusted Firmware is inviting you to a scheduled Zoom meeting.
Join Zoom Meeting
Meeting ID: 915 970 4974
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================
Joanna
On 19/05/2021, 03:50, "Madhukar Pappireddy" Madhukar.Pappireddy@arm.com wrote:
Attached slides presented by Manish in the TF-A tech forum.
-----Original Message-----
From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Madhukar Pappireddy via TF-A
Sent: Tuesday, May 18, 2021 8:59 PM
To: Joanna Farley Joanna.Farley@arm.com; Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org
Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; tf-a@lists.trustedfirmware.org; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi,
I tried to summarize the discussions in the previous TF-A tech forum regarding the proposal to adopt Hand-off Blocks (HOBs) for passing information along the boot chain. I am certain I could not capture all suggestions/concerns brought up during the call. I apologize if I missed and/or misinterpreted any comments and would appreciate it if everyone could share their thoughts in response to this email thread.
The idea is to share information to other boot phases:
> Dynamic information: Created during runtime. Shared in the form of a chain of blobs(built as a linked list of C structure objects i.e., HOB list).
> Static information: Known at compile time. Historically, shared through the use of Device Tree/ACPI tables
Both the above requirements are common in many ecosystems and need to co-exist.
There are broadly 3 problems to solve:
1. Format of HOB structures: It looks like the consensus is that we could use existing mechanisms for this (BL_AUX_PARAM in TF-A or bloblist in u-boot).
2. Identification of HOB list entries: There is a debate about whether tags would suffice or if the HOB list producer and consumer would depend on UUID/GUIDs for identifying a specific HOB structure. Another suggestion was to use a hybrid approach. Reserve a single tag ID for identifying/constructing a HOB structure that further leverages UUID based identifier. This way, the generic HOB list doesn't need to support UUIDs and can work with tags.
3. The design contract for the static interface between two boot phases: The problem at hand is whether to pass a pointer to a HOB list or a device tree blob through the general-purpose registers for configuration hand-off between two boot phases. Some proposals that came up:
> Proposal 1: Always pass a pointer to the device tree blob through the GP register and capture the pointer to the HOB list as a property of a node that is uniquely identifiable by the downstream boot phase. This needs to define a device tree binding such that producer and consumer agree on the information passed.
> Proposal 2: Pass a pointer to a generic container through the GP register that can be interpreted appropriately by both boot loaders(i.e., producer and consumer of the boot info). This container can either be a dtb or a HOB list which can be simply inferred by checking for a magic header that indicates if the buffer appears to be a flattened device tree.
> One another concern that was brought up offline is to make sure we don't break current design contracts between various boot loader phases in TF-A. Many of the general-purpose registers have a designated purpose such as to share configurations between BL images( such as firmware config dtb, SoC config dtb, Non trusted firmware config dtb, memory layout, entry point info, etc.).
If I am not mistaken, a single design may not fit the needs of every segment(client, Infra, embedded) and the forum is open to solutions tailored for individual segments. Joanna will be sending a follow up email with more information about future TF-A tech forums that serves as a platform for further discussions.
Thanks,
Madhukar
-----Original Message-----
From: TF-A tf-a-bounces@lists.trustedfirmware.org On Behalf Of Joanna Farley via TF-A
Sent: Sunday, May 16, 2021 5:19 AM
To: Okash Khawaja okash.khawaja@gmail.com; Simon Glass sjg@chromium.org
Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Apologies I failed with the recording. Manish/Madhu will reply early next week with the slides and some notes to help with a follow up session which we hope to hold this Thursday. Invite and agenda will also be sent out early next week.
Thanks
Joanna
On 14/05/2021, 13:30, "TF-A on behalf of Okash Khawaja via TF-A" <tf-a-bounces@lists.trustedfirmware.org on behalf of tf-a@lists.trustedfirmware.org> wrote:
Hi,
Do we have slides and video from last week's discussion?
Thanks,
Okash
On Wed, May 5, 2021 at 11:52 PM Simon Glass via TF-A
tf-a@lists.trustedfirmware.org wrote:
>
> Hi Harb,
>
> Thanks for the idea. I am still not completely sure what benefit UUID provides to an open project. I'd like to propose something different, more in the spirit of open collaboration. I also worry that the word 'standard' seems to be a synonym for UUIDs, UEFI, etc., i.e. enabling/preferring closed-source firmware and the continued decline of open-source projects. It really should not be.
>
> So I suggest: Use simple integer IDs and reserve some area for 'private' use. If you want to collaborate across projects outside your company, you either need to allocate a 'public' ID or agree privately between the parties which private ID to use.
>
> This means that the default and easiest option is for collaboration and a public ID, with private ones (whose purpose may be secret) reserved just for private use.
>
> Regards,
> Simon
>
> On Wed, 5 May 2021 at 11:42, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote:
>>
>> Hey Folks,
>>
>> We wanted to put out a middle-ground proposal to help guide the discussion on the call tomorrow.
>>
>>
>>
>> A proposal that we have been discussing offline involves reserving a single tag ID for the purpose of construction UEFI PI HOB List structure, and that tag would be used to identify a HOB-specific structure that does leverage UUID based identifier. This will eliminate the burden of having to support UUID as the tag, and this enables projects that require UUID based identifiers for the broad range of HOB structures that need to be produced during the booting of the platform. Once we have a tag for a HOB list, this will enable various HOB producers that can add/extend the HOB list in TF-A code (or even pre-TF-A code), with a HOB consumer for that UUID/GUID on the other side (i.e. whatever the BL33 image is booting on that platform).
>>
>>
>>
>> Essentially, the idea is if someone would like to support HOB structures in a standard way using TF-A, they would wrap it up in a BL_AUX_PARAM/BLOB structure (whatever the group decides) and the way we identify the structure as a HOB list is with this new reserved tag.
>>
>>
>>
>> Hopefully that makes sense and less contentious. Look forward to discuss this further on the call.
>>
>>
>>
>> Thanks,
>>
>> --Harb
>>
>>
>>
>> From: Manish Pandey2 Manish.Pandey2@arm.com
>> Sent: Friday, April 30, 2021 8:14 AM
>> To: François Ozog francois.ozog@linaro.org
>> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> Hi All,
>>
>>
>>
>> Please find invite for next TF-A Tech Forum session to continue our discussions on HOB implementation, feel free to forward it to others.
>>
>>
>>
>> The next TF-A Tech Forum is scheduled for Thu 6th May 2021 16:00 – 17:00 (BST).
>>
>>
>>
>> Agenda:
>>
>> Discussion Session: Static and Dynamic Information Handling in TF-A
>>
>> Lead by Manish Pandey and Madhukar Pappireddy
>>
>> · There is ongoing mailing lists discussion[1] related with adopting a mechanism to pass information through boot stages.
>>
>> The requirement is two-fold:
>>
>> 1. Passing static information(config files)
>>
>> 2. Passing dynamic information (Hob list)
>>
>> In the upcoming TF-A tech forum, we can start with a discussion on dynamic information passing and if time permits, we can cover static information passing. The purpose of the call is to have an open discussion and continue the discussion from the trusted-substrate call[2] done earlier. We would like to understand the various requirements and possible ways to implement it in TF-A in a generalized way so that it can work with other Firmware projects.
>>
>>
>>
>> The two specific item which we would like to discuss are:
>>
>> 1. HOB format: TF-A/u-boot both has an existing bloblist implementation, which uses tag values. Question, can this be enhanced to use hybrid values(Tag and UUID) both?
>>
>> 2. Standardization on Physical register use to pass base of HoB data structure.
>>
>> References:
>>
>> [1] https://lists.trustedfirmware.org/pipermail/tf-a/2021-April/001069.html
>>
>> [2] https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%
>>
>>
>>
>> Thanks
>>
>>
>>
>> Joanna
>>
>>
>>
>> You have been invited to the following event.
>>
>> TF-A Tech Forum
>>
>> When
>>
>> Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time
>>
>> Calendar
>>
>> tf-a@lists.trustedfirmware.org
>>
>> Who
>>
>> •
>>
>> Bill Fletcher- creator
>>
>> •
>>
>> tf-a@lists.trustedfirmware.org
>>
>> more details »
>>
>>
>>
>> We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
>>
>>
>>
>> Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
>>
>>
>>
>> Trusted Firmware is inviting you to a scheduled Zoom meeting.
>>
>>
>>
>> Join Zoom Meeting
>>
>> https://zoom.us/j/9159704974
>>
>>
>>
>> Meeting ID: 915 970 4974
>>
>>
>>
>> One tap mobile
>>
>> +16465588656,,9159704974# US (New York)
>>
>> +16699009128,,9159704974# US (San Jose)
>>
>>
>>
>> Dial by your location
>>
>> +1 646 558 8656 US (New York)
>>
>> +1 669 900 9128 US (San Jose)
>>
>> 877 853 5247 US Toll-free
>>
>> 888 788 0099 US Toll-free
>>
>> Meeting ID: 915 970 4974
>>
>> Find your local number: https://zoom.us/u/ad27hc6t7h
>>
>>
>>
>> ________________________________
>>
>> From: François Ozog francois.ozog@linaro.org
>> Sent: 08 April 2021 16:50
>> To: Manish Pandey2 Manish.Pandey2@arm.com
>> Cc: Simon Glass sjg@chromium.org; Julius Werner jwerner@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> Hi
>>
>>
>>
>> here is the meeting recording:
>>
>> https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%z
>>
>>
>>
>> I am really sorry about the confusion related to the meeting time. I have now understood: the Collaborate portal uses a specific calendar which is tied to US/Chicago timezone while the actual Google Calendar is tied to Central Europe timezone. I am going to drop the Collaborate portal and use a shared Google calendar (it should be visible on the trusted-substrate.org page).
>>
>>
>>
>> I'll try to summarize what I learnt and highlight my view on what can be next steps in a future mail.
>>
>>
>>
>> Cheers
>>
>>
>>
>> FF
>>
>>
>>
>> On Thu, 8 Apr 2021 at 13:56, Manish Pandey2 via TF-A tf-a@lists.trustedfirmware.org wrote:
>>
>> Hi,
>>
>>
>>
>> From TF-A project point of view, we prefer to use existing mechanism to pass parameters across boot stages using linked list of tagged elements (as suggested by Julius). It has support for both generic and SiP-specific tags. Having said that, it does not stop partners to introduce new mechanisms suitable for their usecase in platform port initially and later move to generic code if its suitable for other platforms.
>>
>>
>>
>> To start with, Ampere can introduce a platform specific implementation of memory tag(speed/NUMA topology etc) which can be evaluated and discussed for generalization in future. The tag will be populated in BL2 stage and can be forwarded to further stages(and to BL33) by passing the head of list pointer in one of the registers. Initially any register can be used but going forward a standardization will be needed.
>>
>>
>>
>> The U-boot bloblist mentioned by Simon is conceptually similar to what TF-A is using, if there is consensus of using bloblist/taglist then TF-A tag list may be enhanced to take best of both the implementations.
>>
>>
>>
>> One of the potential problems of having structure used in different projects is maintainability, this can be avoided by having a single copy of these structures in TF-A (kept inside "include/export" which intended to be used by other projects.)
>>
>>
>>
>> Regarding usage of either UUID or tag, I echo the sentiments of Simon and Julius to keep it simple and use tag values.
>>
>>
>>
>> Looking forward to having further discussions on zoom call today.
>>
>>
>>
>> Thanks
>>
>> Manish P
>>
>>
>>
>> ________________________________
>>
>> From: TF-A tf-a-bounces@lists.trustedfirmware.org on behalf of Julius Werner via TF-A tf-a@lists.trustedfirmware.org
>> Sent: 25 March 2021 02:43
>> To: Simon Glass sjg@chromium.org
>> Cc: Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> Just want to point out that TF-A currently already supports a (very simple) mechanism like this:
>>
>>
>>
>> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>>
>> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>>
>> https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>>
>>
>>
>> It's just a linked list of tagged elements. The tag space is split into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31.
>>
>>
>>
>> I would echo Simon's sentiment of keeping this as simple as possible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once.
>>
>>
>>
>> On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A tf-a@lists.trustedfirmware.org wrote:
>>
>> Hi Harb,
>>
>>
>>
>> On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS abdulhamid@os.amperecomputing.com wrote:
>>
>> Hello Folks,
>>
>> Appreciate the feedback and replies on this. Glad to see that there is interest in this topic.
>>
>>
>>
>> I try to address the comments/feedback from Francois and Simon below….
>>
>>
>>
>> @François Ozog – happy to discuss this on a zoom call. I will make that time slot work, and will be available to attend April 8, 4pm CT.
>>
>>
>>
>> Note that I’m using the term “HOB” here more generically, as there are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases.
>>
>>
>>
>> The whole point here is to provide mechanism to develop firmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM).
>>
>>
>>
>> Keep in mind, in the server/datacenter market segment we are not building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model:
>>
>> “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2, BL31, and *possibly* one or more BL32 instances
>> “Platform” or “board” firmware – in TF-A this may map to BL33 and *possibly* one or more BL32 instances.
>>
>>
>>
>> Even the platform firmware stack could be further fragmented by having multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code.
>>
>>
>>
>> To support a broad range of platform designs with a broad range of memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software.
>>
>>
>>
>> I understand the versatility of DT, but I see two major problems with DT:
>>
>> DT requires more complicated parsing to get properties, and even more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained.
>> DT is probably overkill for this purpose – We really just want a list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob)
>>
>>
>>
>> I think that we should not mix the efforts around DT/ACPI specs with what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs).
>>
>>
>>
>> Frankly, I would personally push back pretty hard on defining SMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls.
>>
>>
>>
>> Please do let me know if you disagree and why. Look forward to discussing on this thread or on the call.
>>
>>
>>
>> @Simon Glass - Thanks for the pointer to bloblist. I briefly reviewed and it seems like a good baseline for what we may be looking for.
>>
>>
>>
>> That being said, I would say that there is some benefit in having some kind of unique identifiers (e.g. UUID or some unique signature) so that we can tie standardized data structures (based on some future TBD specs) to a particular ID. For example, if the TPM driver in BL33 is looking for the TPM structure in the HOB/BOB list, and may not care about the other data blobs. The driver needs a way to identify and locate the blob it cares about.
>>
>>
>>
>> The tag is intended to serve that purpose, although perhaps it should switch from an auto-allocating enum to one with explicit values for each entry and a range for 'local' use.
>>
>>
>>
>> I guess we can achieve this with the tag, but the problem with tag when you have eco-system with a lot of parties doing parallel development, you can end up with tag collisions and folks fighting about who has rights to what tag values. We would need some official process for folks to register tags for whatever new structures we define, or maybe some tag range for vendor specific structures. This comes with a lot of pain and bureaucracy. On the other hand, UUID has been a proven way to make it easy to just define your own blobs with *either* standard or vendor specific structures without worry of ID collisions between vendors.
>>
>>
>>
>> True. I think the pain is overstated, though. In this case I think we actually want something that can be shared between projects and orgs, so some amount of coordination could be considered a benefit. It could just be a github pull request. I find the UUID unfriendly and not just to code size and eyesight! Trying to discover what GUIDs mean or are valid is quite tricky. E.g. see this code:
>>
>>
>>
>> #define FSP_HOB_RESOURCE_OWNER_TSEG_GUID \
>> EFI_GUID(0xd038747c, 0xd00c, 0x4980, \
>> 0xb3, 0x19, 0x49, 0x01, 0x99, 0xa4, 0x7d, 0x55)
>>
>> (etc.)
>>
>>
>>
>> static struct guid_name {
>> efi_guid_t guid;
>> const char *name;
>> } guid_name[] = {
>> { FSP_HOB_RESOURCE_OWNER_TSEG_GUID, "TSEG" },
>> { FSP_HOB_RESOURCE_OWNER_FSP_GUID, "FSP" },
>> { FSP_HOB_RESOURCE_OWNER_SMM_PEI_SMRAM_GUID, "SMM PEI SMRAM" },
>> { FSP_NON_VOLATILE_STORAGE_HOB_GUID, "NVS" },
>> { FSP_VARIABLE_NV_DATA_HOB_GUID, "Variable NVS" },
>> { FSP_GRAPHICS_INFO_HOB_GUID, "Graphics info" },
>> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID1, "PCD database ea" },
>> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID2, "PCD database 9b" },
>>
>> (never figured out what those two are)
>>
>>
>> { FSP_HOB_RESOURCE_OWNER_PEIM_DXE_GUID, "PEIM Init DXE" },
>> { FSP_HOB_RESOURCE_OWNER_ALLOC_STACK_GUID, "Alloc stack" },
>> { FSP_HOB_RESOURCE_OWNER_SMBIOS_MEMORY_GUID, "SMBIOS memory" },
>> { {}, "zero-guid" },
>> {}
>> };
>>
>> static const char *guid_to_name(const efi_guid_t *guid)
>> {
>> struct guid_name *entry;
>>
>> for (entry = guid_name; entry->name; entry++) {
>> if (!guidcmp(guid, &entry->guid))
>> return entry->name;
>> }
>>
>> return NULL;
>> }
>>
>>
>>
>> Believe it or not it took a fair bit of effort to find just that small list, with nearly every one in a separate doc, from memory.
>>
>>
>>
>>
>>
>> We can probably debate whether there is any value in GUID/UUID or not during the call… but again, boblist seems like a reasonable starting point as an alternative to HOB.
>>
>>
>>
>> Indeed. There is certainly value in both approaches.
>>
>>
>>
>> Regards,
>>
>> Simon
>>
>>
>>
>>
>>
>> Thanks,
>>
>> --Harb
>>
>>
>>
>> From: François Ozog francois.ozog@linaro.org
>> Sent: Tuesday, March 23, 2021 10:00 AM
>> To: François Ozog francois.ozog@linaro.org; Ron Minnich rminnich@google.com; Paul Isaac's paul.isaacs@linaro.org
>> Cc: Simon Glass sjg@chromium.org; Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
>>
>>
>>
>> +Ron Minnich +Paul Isaac's
>>
>>
>>
>> Adding Ron and Paul because I think this interface should be also benefiting LinuxBoot efforts.
>>
>>
>>
>> On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A tf-a@lists.trustedfirmware.org wrote:
>>
>> Hi,
>>
>>
>>
>> I propose we cover the topic at the next Trusted Substrate zoom call on April 8th 4pm CET.
>>
>>
>>
>> The agenda:
>>
>> ABI between non-secure firmware and the rest of firmware (EL3, S-EL1, S-EL2, SCP) to adapt hardware description to some runtime conditions.
>>
>> runtime conditions here relates to DRAM size and topology detection, secure DRAM memory carvings, PSCI and SCMI interface publishing.
>>
>>
>>
>> For additional background on existing metadata: UEFI Platform Initialization Specification Version 1.7, 5.5 Resource Descriptor HOB
>>
>> Out of the ResourceType we care about is EFI_RESOURCE_SYSTEM_MEMORY.
>>
>> This HOB lacks memory NUMA attachment or something that could be related to fill SRAT table for ACPI or relevant DT proximity domains.
>>
>> HOB is not consistent accros platforms: some platforms (Arm) lists memory from the booting NUMA node, other platforms (x86) lists all memory from all NUMA nodes. (At least this is the case on the two platforms I tested).
>>
>>
>>
>> There are two proposals to use memory structures from SPL/BLx up to the handover function (as defined in the Device Tree technical report) which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or EDK2.
>>
>> I would propose we also discuss possibility of FF-A interface to actually query information or request actions to be done (this is a model actually used in some SoCs with proprietary SMC calls).
>>
>>
>>
>> Requirements (to be validated):
>>
>> - ACPI and DT hardware descriptions.
>>
>> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2)
>>
>> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot, TF-A/EDK2, TF-A/LinuxBoot)
>>
>> - at least allows complete DRAM description and "persistent" usage (reserved areas for secure world or other usages)
>>
>> - support secure world device assignment
>>
>>
>>
>> Cheers
>>
>>
>>
>> FF
>>
>>
>>
>>
>>
>> On Mon, 22 Mar 2021 at 19:56, Simon Glass sjg@chromium.org wrote:
>>
>> Hi,
>>
>> Can I suggest using bloblist for this instead? It is lightweight,
>> easier to parse, doesn't have GUIDs and is already used within U-Boot
>> for passing info between SPL/U-Boot, etc.
>>
>> Docs here: https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist
>> Header file describes the format:
>> https://github.com/u-boot/u-boot/blob/master/include/bloblist.h
>>
>> Full set of unit tests:
>> https://github.com/u-boot/u-boot/blob/master/test/bloblist.c
>>
>> Regards,
>> Simon
>>
>> On Mon, 22 Mar 2021 at 23:58, François Ozog francois.ozog@linaro.org wrote:
>> >
>> > +Boot Architecture Mailman List boot-architecture@lists.linaro.org
>> >
>> > standardization is very much welcomed here and need to accommodate a very
>> > diverse set of situations.
>> > For example, TEE OS may need to pass memory reservations to BL33 or
>> > "capture" a device for the secure world.
>> >
>> > I have observed a number of architectures:
>> > 1) pass information from BLx to BLy in the form of a specific object
>> > 2) BLx called by BLy by a platform specific SMC to get information
>> > 3) BLx called by BLy by a platform specific SMC to perform Device Tree
>> > fixups
>> >
>> > I also imagined a standardized "broadcast" FF-A call so that any firmware
>> > element can either provide information or "do something".
>> >
>> > My understanding of your proposal is about standardizing on architecture 1)
>> > with the HOB format.
>> >
>> > The advantage of the HOB is simplicity but it may be difficult to implement
>> > schemes such as pruning a DT because device assignment in the secure world.
>> >
>> > In any case, it looks feasible to have TF-A and OP-TEE complement the list
>> > of HOBs to pass information downstream (the bootflow).
>> >
>> > It would be good to start with building the comprehensive list of
>> > information that need to be conveyed between firmware elements:
>> >
>> > information. | authoritative entity | reporting entity | information
>> > exchanged:
>> > dram | TFA | TFA |
>> > <format to be detailed, NUMA topology to build the SRAT table or DT
>> > equivalent?>
>> > PSCI | SCP | TFA? |
>> > SCMI | SCP or TEE-OS | TFA? TEE-OS?|
>> > secure SRAM | TFA. | TFA. |
>> > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? |
>> > other? | |
>> > |
>> >
>> > Cheers
>> >
>> > FF
>> >
>> >
>> > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A <
>> > tf-a@lists.trustedfirmware.org> wrote:
>> >
>> > > Hello Folks,
>> > >
>> > >
>> > >
>> > > I'm emailing to start an open discussion about the adoption of a concept
>> > > known as "hand-off blocks" or HOB to become a part of the TF-A Firmware
>> > > Framework Architecture (FFA). This is something that is a pretty major
>> > > pain point when it comes to the adoption of TF-A in ARM Server SoC’s
>> > > designed to enable a broad range of highly configurable datacenter
>> > > platforms.
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > What is a HOB (Background)?
>> > >
>> > > ---------------------------
>> > >
>> > > UEFI PI spec describes a particular definition for how HOB may be used for
>> > > transitioning between the PEI and DXE boot phases, which is a good
>> > > reference point for this discussion, but not necessarily the exact solution
>> > > appropriate for TF-A.
>> > >
>> > >
>> > >
>> > > A HOB is simply a dynamically generated data structure passed in between
>> > > two boot phases. This is information that was obtained through discovery
>> > > and needs to be passed forward to the next boot phase *once*, with no API
>> > > needed to call back (e.g. no call back into previous firmware phase is
>> > > needed to fetch this information at run-time - it is simply passed one time
>> > > during boot).
>> > >
>> > >
>> > >
>> > > There may be one or more HOBs passed in between boot phases. If there are
>> > > more than one HOB that needs to be passed, this can be in a form of a "HOB
>> > > table", which (for example) could be a UUID indexed array of pointers to
>> > > HOB structures, used to locate a HOB of interest (based on UUID). In such
>> > > cases, instead of passing a single HOB, the boot phases may rely on passing
>> > > the pointer to the HOB table.
>> > >
>> > >
>> > >
>> > > This has been extremely useful concept to employ on highly configurable
>> > > systems that must rely on flexible discovery mechanisms to initialize and
>> > > boot the system. This is especially helpful when you have multiple
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > Why do we need HOBs in TF-A?:
>> > >
>> > > -----------------------------
>> > >
>> > > It is desirable that EL3 firmware (e.g. TF-A) built for ARM Server SoC in
>> > > a way that is SoC specific *but* platform agnostic. This means that a
>> > > single ARM SoC that a SiP may deliver to customers may provide a single
>> > > TF-A binary (e.g. BL1, BL2, BL31) that could be used to support a broad
>> > > range of platform designs and configurations in order to boot a platform
>> > > specific firmware (e.g. BL33 and possibly even BL32 code). In order to
>> > > achieve this, the platform configuration must be *discovered* instead of
>> > > statically compiled as it is today in TF-A via device tree based
>> > > enumeration. The mechanisms of discovery may differ broadly depending on
>> > > the relevant industry standard, or in some cases may have rely on SiP
>> > > specific discovery flows.
>> > >
>> > >
>> > >
>> > > For example: On server systems that support a broad range DIMM memory
>> > > population/topologies, all the necessary information required to boot is
>> > > fully discovered via standard JEDEC Serial Presence Detect (SPD) over an
>> > > I2C bus. Leveraging the SPD bus, may platform variants could be supported
>> > > with a single TF-A binary. Not only is this information required to
>> > > initialize memory in early boot phases (e.g. BL2), the subsequent boot
>> > > phases will also need this SPD info to construct a system physical address
>> > > map and properly initialize the MMU based on the memory present, and where
>> > > the memory may be present. Subsequent boot phases (e.g. BL33 / UEFI) may
>> > > need to generate standard firmware tables to the operating systems, such as
>> > > SMBIOS tables describing DIMM topology and various ACPI tables (e.g. SLIT,
>> > > SRAT, even NFIT if NVDIMM's are present).
>> > >
>> > >
>> > >
>> > > In short, it all starts with a standardized or vendor specific discovery
>> > > flow in an early boot stage (e.g. BL1/BL2), followed by the passing of
>> > > information to the next boot stages (e.g. BL31/BL32/BL33).
>> > >
>> > >
>> > >
>> > > Today, every HOB may be a vendor specific structure, but in the future
>> > > there may be benefit of defining standard HOBs. This may be useful for
>> > > memory discovery, passing the system physical address map, enabling TPM
>> > > measured boot, and potentially many other common HOB use-cases.
>> > >
>> > >
>> > >
>> > > It would be extremely beneficial to the datacenter market segment if the
>> > > TF-A community would adopt this concept of information passing between all
>> > > boot phases as opposed to rely solely on device tree enumeration. This is
>> > > not intended to replace device tree, rather intended as an alternative way
>> > > to describe the info that must be discovered and dynamically generated.
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > Conclusion:
>> > >
>> > > -----------
>> > >
>> > > We are proposing that the TF-A community begin pursuing the adoption of
>> > > HOBs as a mechanism used for information exchange between each boot stage
>> > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)? Longer term we
>> > > want to explore standardizing some HOB structures for the BL33 phase (e.g.
>> > > UEFI HOB structures), but initially would like to agree on this being a
>> > > useful mechanism used to pass information between each boot stage.
>> > >
>> > >
>> > >
>> > > Thanks,
>> > >
>> > > --Harb
>> > >
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > --
>> > > TF-A mailing list
>> > > TF-A@lists.trustedfirmware.org
>> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>> > >
>> >
>> >
>> > --
>> > François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group*
>> > T: +33.67221.6485
>> > francois.ozog@linaro.org | Skype: ffozog
>> > _______________________________________________
>> > boot-architecture mailing list
>> > boot-architecture@lists.linaro.org
>> > https://lists.linaro.org/mailman/listinfo/boot-architecture
>>
>>
>>
>>
>> --
>>
>> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group
>>
>> T: +33.67221.6485
>> francois.ozog@linaro.org | Skype: ffozog
>>
>>
>>
>> --
>> TF-A mailing list
>> TF-A@lists.trustedfirmware.org
>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>>
>>
>>
>>
>> --
>>
>> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group
>>
>> T: +33.67221.6485
>> francois.ozog@linaro.org | Skype: ffozog
>>
>>
>>
>> --
>> TF-A mailing list
>> TF-A@lists.trustedfirmware.org
>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>>
>> --
>> TF-A mailing list
>> TF-A@lists.trustedfirmware.org
>> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
>>
>>
>>
>>
>> --
>>
>> François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group
>>
>> T: +33.67221.6485
>> francois.ozog@linaro.org | Skype: ffozog
>>
>>
>
> --
> TF-A mailing list
> TF-A@lists.trustedfirmware.org
> https://lists.trustedfirmware.org/mailman/listinfo/tf-a
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On Thu, 10 Jun 2021 at 23:57, Manish Pandey2 Manish.Pandey2@arm.com wrote:
Hi Everyone,
I have tried to conclude the discussions we had in two of the TF-A tech forum sessions and on mailing list.
The problem we are trying to solve is already solved in different projects in different ways, the purpose of these discussions was to come up with a standard way which can be adopted widely. Considering that many Firmware projects are not DT aware its better to avoid its usage and use simple C structures for wider acceptance. Based on the discussions following design came up as most acceptable solution
- Use list of pre-defined C data structures(blobs) to pass
information, let's call it bloblist
- Only bootloaders stages will participate
- Blobs will be identified by either tags or UUIDs
- Pass pointer to the bloblist head through x0
- Existing usage of x0 will be translated into a blob
After all discussions, I now support Simon proposal to use existing
bloblist: it does the job, is already upstream in key projects (core boot, U-Boot), is supported on x86 and Arm.
I would think of a few additions on the bloblist_rec:
struct bloblist_rec https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/bloblist_rec { u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 tag https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/tag; u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 hdr_size https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/hdr_size; u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 size; u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 spare https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/spare;};
enum bloblist_tag_t https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/bloblist_tag_t { BLOBLISTT_NONE https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_NONE = 0,
/* Vendor-specific tags are permitted here */ BLOBLISTT_EC_HOSTEVENT https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_EC_HOSTEVENT, /* Chromium OS EC host-event mask */ BLOBLISTT_SPL_HANDOFF https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_SPL_HANDOFF, /* Hand-off info from SPL */ BLOBLISTT_VBOOT_CTX https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_VBOOT_CTX, /* Chromium OS verified boot context */ BLOBLISTT_VBOOT_HANDOFF https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_VBOOT_HANDOFF, /* Chromium OS internal handoff info */ /* * Advanced Configuration and Power Interface Global Non-Volatile * Sleeping table. This forms part of the ACPI tables passed to Linux. */ BLOBLISTT_ACPI_GNVS https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_ACPI_GNVS, BLOBLISTT_INTEL_VBT https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_INTEL_VBT, /* Intel Video-BIOS table */ BLOBLISTT_TPM2_TCG_LOG https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_TPM2_TCG_LOG, /* TPM v2 log space */ BLOBLISTT_TCPA_LOG https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_TCPA_LOG, /* TPM log space */ BLOBLISTT_ACPI_TABLES https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_ACPI_TABLES, /* ACPI tables for x86 */ BLOBLISTT_SMBIOS_TABLES https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_SMBIOS_TABLES, /* SMBIOS tables for x86 */
BLOBLISTT_COUNT https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_COUNT};
I would add a BLOBLISTT_UUID for all proprietary things that people want to add. Using private space in a 64 bit field does not make the thing open. So by using this tag, we know exactly the nature of the blob. Negotiating for adding a new tag is a good open governance process.
We may have to deal with super small SRAM (256KB) and thus we can assume the bloblist will be a single region of blobs. So I would add a BLOBLISTT_CONTINUATION which would be a pointer from the SRAM bloblist to a DRAM backed bloblist.
Other tags to consider: PSCI interface details, DRAM information, SCMI stuff, Secure SRAM and DRAM information...
- Going forward we would provide core changes to demonstrate this
design on various TF-A boundries, BL1<->BL2, BL2<->BL31 and BL31<->BL33(only BL31 part)
Please share your thoughts if you disagree to the proposed solution.
Also, refer to attached slide deck which was presented during last tech forum session on 3rd june, it also captures the points discussed during meeting and next steps for implementing it in TF-A.
Thanks Manish Pandey
*From:* Joanna Farley Joanna.Farley@arm.com *Sent:* 02 June 2021 16:26 *To:* Madhukar Pappireddy Madhukar.Pappireddy@arm.com; Okash Khawaja < okash.khawaja@gmail.com>; Simon Glass sjg@chromium.org *Cc:* Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's < paul.isaacs@linaro.org>; Ron Minnich rminnich@google.com; Moe Ammar < moe@amperecomputing.com>; tf-a@lists.trustedfirmware.org < tf-a@lists.trustedfirmware.org>; Manish Pandey2 Manish.Pandey2@arm.com *Subject:* Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
- TF-A list that got dropped (again)!
Joanna
*From: *Joanna Farley Joanna.Farley@arm.com *Date: *Wednesday, 2 June 2021 at 15:29 *To: *Madhukar Pappireddy Madhukar.Pappireddy@arm.com, Okash Khawaja < okash.khawaja@gmail.com>, Simon Glass sjg@chromium.org *Cc: *Harb Abdulhamid OS abdulhamid@os.amperecomputing.com, Boot Architecture Mailman List boot-architecture@lists.linaro.org, Ed Stuber edstuber@amperecomputing.com, Arjun Khare akhare@amperecomputing.com, U-Boot Mailing List u-boot@lists.denx.de, Paul Isaac's < paul.isaacs@linaro.org>, Ron Minnich rminnich@google.com, Moe Ammar < moe@amperecomputing.com> *Subject: *Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi Everyone,
The Manish Pandy and Madhukar Pappireddy of the TF-A team are planning to host another TF-A Tech Forum this Thursday to continue the live discussion.
Here is their agenda:
On tech forum this week, we would like to continue discussions on HOB list design.
The topics which we would like to cover is
Evaluate different proposals of passing information through boot phases.
If we don't get an agreement on one solution fit for all then we would
try to get consensus for Infra segment platform(to solve original problem mentioned by Harb)
- Try to get an agreement on size of tags and how "hybrid and tag only"
HOB list can co-exist together?
Details of the call are:
======================
TF-A Tech Forum
When Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time
Calendar tf-a@lists.trustedfirmware.org
Who • Bill Fletcher- creator
• tf-a@lists.trustedfirmware.org
We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
Trusted Firmware is inviting you to a scheduled Zoom meeting.
Join Zoom Meeting
Meeting ID: 915 970 4974
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================
Joanna
On 19/05/2021, 03:50, "Madhukar Pappireddy" Madhukar.Pappireddy@arm.com wrote:
Attached slides presented by Manish in the TF-A tech forum. -----Original Message----- From: TF-A <tf-a-bounces@lists.trustedfirmware.org> On Behalf OfMadhukar Pappireddy via TF-A
Sent: Tuesday, May 18, 2021 8:59 PM To: Joanna Farley <Joanna.Farley@arm.com>; Okash Khawaja <okash.khawaja@gmail.com>; Simon Glass sjg@chromium.org
Cc: Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>; BootArchitecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List u-boot@lists.denx.de; tf-a@lists.trustedfirmware.org; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) forinformation passing between boot stages
Hi, I tried to summarize the discussions in the previous TF-A tech forumregarding the proposal to adopt Hand-off Blocks (HOBs) for passing information along the boot chain. I am certain I could not capture all suggestions/concerns brought up during the call. I apologize if I missed and/or misinterpreted any comments and would appreciate it if everyone could share their thoughts in response to this email thread.
The idea is to share information to other boot phases: > Dynamic information: Created during runtime. Shared in the form of achain of blobs(built as a linked list of C structure objects i.e., HOB list).
> Static information: Known at compile time. Historically, sharedthrough the use of Device Tree/ACPI tables
Both the above requirements are common in many ecosystems and need toco-exist.
There are broadly 3 problems to solve: 1. Format of HOB structures: It looks like the consensus is that wecould use existing mechanisms for this (BL_AUX_PARAM in TF-A or bloblist in u-boot).
2. Identification of HOB list entries: There is a debate about whethertags would suffice or if the HOB list producer and consumer would depend on UUID/GUIDs for identifying a specific HOB structure. Another suggestion was to use a hybrid approach. Reserve a single tag ID for identifying/constructing a HOB structure that further leverages UUID based identifier. This way, the generic HOB list doesn't need to support UUIDs and can work with tags.
3. The design contract for the static interface between two bootphases: The problem at hand is whether to pass a pointer to a HOB list or a device tree blob through the general-purpose registers for configuration hand-off between two boot phases. Some proposals that came up:
> Proposal 1: Always pass a pointer to the device tree blobthrough the GP register and capture the pointer to the HOB list as a property of a node that is uniquely identifiable by the downstream boot phase. This needs to define a device tree binding such that producer and consumer agree on the information passed.
> Proposal 2: Pass a pointer to a generic container throughthe GP register that can be interpreted appropriately by both boot loaders(i.e., producer and consumer of the boot info). This container can either be a dtb or a HOB list which can be simply inferred by checking for a magic header that indicates if the buffer appears to be a flattened device tree.
> One another concern that was brought up offline is to makesure we don't break current design contracts between various boot loader phases in TF-A. Many of the general-purpose registers have a designated purpose such as to share configurations between BL images( such as firmware config dtb, SoC config dtb, Non trusted firmware config dtb, memory layout, entry point info, etc.).
If I am not mistaken, a single design may not fit the needs of everysegment(client, Infra, embedded) and the forum is open to solutions tailored for individual segments. Joanna will be sending a follow up email with more information about future TF-A tech forums that serves as a platform for further discussions.
Thanks, Madhukar -----Original Message----- From: TF-A <tf-a-bounces@lists.trustedfirmware.org> On Behalf OfJoanna Farley via TF-A
Sent: Sunday, May 16, 2021 5:19 AM To: Okash Khawaja <okash.khawaja@gmail.com>; Simon Glass <sjg@chromium.org>
Cc: Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>; BootArchitecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List < u-boot@lists.denx.de>; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) forinformation passing between boot stages
Apologies I failed with the recording. Manish/Madhu will reply earlynext week with the slides and some notes to help with a follow up session which we hope to hold this Thursday. Invite and agenda will also be sent out early next week.
Thanks Joanna On 14/05/2021, 13:30, "TF-A on behalf of Okash Khawaja via TF-A" <tf-a-bounces@lists.trustedfirmware.org on behalf of tf-a@lists.trustedfirmware.org> wrote:
Hi, Do we have slides and video from last week's discussion? Thanks, Okash On Wed, May 5, 2021 at 11:52 PM Simon Glass via TF-A <tf-a@lists.trustedfirmware.org> wrote: > > Hi Harb, > > Thanks for the idea. I am still not completely sure what benefitUUID provides to an open project. I'd like to propose something different, more in the spirit of open collaboration. I also worry that the word 'standard' seems to be a synonym for UUIDs, UEFI, etc., i.e. enabling/preferring closed-source firmware and the continued decline of open-source projects. It really should not be.
> > So I suggest: Use simple integer IDs and reserve some area for'private' use. If you want to collaborate across projects outside your company, you either need to allocate a 'public' ID or agree privately between the parties which private ID to use.
> > This means that the default and easiest option is forcollaboration and a public ID, with private ones (whose purpose may be secret) reserved just for private use.
> > Regards, > Simon > > On Wed, 5 May 2021 at 11:42, Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com> wrote:
>> >> Hey Folks, >> >> We wanted to put out a middle-ground proposal to help guide thediscussion on the call tomorrow.
>> >> >> >> A proposal that we have been discussing offline involvesreserving a single tag ID for the purpose of construction UEFI PI HOB List structure, and that tag would be used to identify a HOB-specific structure that does leverage UUID based identifier. This will eliminate the burden of having to support UUID as the tag, and this enables projects that require UUID based identifiers for the broad range of HOB structures that need to be produced during the booting of the platform. Once we have a tag for a HOB list, this will enable various HOB producers that can add/extend the HOB list in TF-A code (or even pre-TF-A code), with a HOB consumer for that UUID/GUID on the other side (i.e. whatever the BL33 image is booting on that platform).
>> >> >> >> Essentially, the idea is if someone would like to support HOBstructures in a standard way using TF-A, they would wrap it up in a BL_AUX_PARAM/BLOB structure (whatever the group decides) and the way we identify the structure as a HOB list is with this new reserved tag.
>> >> >> >> Hopefully that makes sense and less contentious. Look forwardto discuss this further on the call.
>> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: Manish Pandey2 <Manish.Pandey2@arm.com> >> Sent: Friday, April 30, 2021 8:14 AM >> To: François Ozog <francois.ozog@linaro.org> >> Cc: Simon Glass <sjg@chromium.org>; Julius Werner <jwerner@chromium.org>; Harb Abdulhamid OS < abdulhamid@os.amperecomputing.com>; Boot Architecture Mailman List < boot-architecture@lists.linaro.org>; tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's < paul.isaacs@linaro.org>; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> Hi All, >> >> >> >> Please find invite for next TF-A Tech Forum session to continueour discussions on HOB implementation, feel free to forward it to others.
>> >> >> >> The next TF-A Tech Forum is scheduled for Thu 6th May 202116:00 – 17:00 (BST).
>> >> >> >> Agenda: >> >> Discussion Session: Static and Dynamic Information Handling inTF-A
>> >> Lead by Manish Pandey and Madhukar Pappireddy >> >> · There is ongoing mailing lists discussion[1] relatedwith adopting a mechanism to pass information through boot stages.
>> >> The requirement is two-fold: >> >> 1. Passing static information(config files) >> >> 2. Passing dynamic information (Hob list) >> >> In the upcoming TF-A tech forum, we can start with a discussionon dynamic information passing and if time permits, we can cover static information passing. The purpose of the call is to have an open discussion and continue the discussion from the trusted-substrate call[2] done earlier. We would like to understand the various requirements and possible ways to implement it in TF-A in a generalized way so that it can work with other Firmware projects.
>> >> >> >> The two specific item which we would like to discuss are: >> >> 1. HOB format: TF-A/u-boot both has an existing bloblistimplementation, which uses tag values. Question, can this be enhanced to use hybrid values(Tag and UUID) both?
>> >> 2. Standardization on Physical register use to pass baseof HoB data structure.
>> >> References: >> >> [1]https://lists.trustedfirmware.org/pipermail/tf-a/2021-April/001069.html
>> >> [2]https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%
>> >> >> >> Thanks >> >> >> >> Joanna >> >> >> >> You have been invited to the following event. >> >> TF-A Tech Forum >> >> When >> >> Every 2 weeks from 16:00 to 17:00 on Thursday United KingdomTime
>> >> Calendar >> >> tf-a@lists.trustedfirmware.org >> >> Who >> >> • >> >> Bill Fletcher- creator >> >> • >> >> tf-a@lists.trustedfirmware.org >> >> more details » >> >> >> >> We run an open technical forum call for anyone to participateand it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
>> >> >> >> Feel free to forward this invite to colleagues. Invites are viathe TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
>> >> >> >> Trusted Firmware is inviting you to a scheduled Zoom meeting. >> >> >> >> Join Zoom Meeting >> >> https://zoom.us/j/9159704974 >> >> >> >> Meeting ID: 915 970 4974 >> >> >> >> One tap mobile >> >> +16465588656,,9159704974# US (New York) >> >> +16699009128,,9159704974# US (San Jose) >> >> >> >> Dial by your location >> >> +1 646 558 8656 US (New York) >> >> +1 669 900 9128 US (San Jose) >> >> 877 853 5247 US Toll-free >> >> 888 788 0099 US Toll-free >> >> Meeting ID: 915 970 4974 >> >> Find your local number: https://zoom.us/u/ad27hc6t7h >> >> >> >> ________________________________ >> >> From: François Ozog <francois.ozog@linaro.org> >> Sent: 08 April 2021 16:50 >> To: Manish Pandey2 <Manish.Pandey2@arm.com> >> Cc: Simon Glass <sjg@chromium.org>; Julius Werner <jwerner@chromium.org>; Harb Abdulhamid OS < abdulhamid@os.amperecomputing.com>; Boot Architecture Mailman List < boot-architecture@lists.linaro.org>; tf-a@lists.trustedfirmware.org < tf-a@lists.trustedfirmware.org>; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> Hi >> >> >> >> here is the meeting recording: >> >>https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%z
>> >> >> >> I am really sorry about the confusion related to the meetingtime. I have now understood: the Collaborate portal uses a specific calendar which is tied to US/Chicago timezone while the actual Google Calendar is tied to Central Europe timezone. I am going to drop the Collaborate portal and use a shared Google calendar (it should be visible on the trusted-substrate.org page).
>> >> >> >> I'll try to summarize what I learnt and highlight my view onwhat can be next steps in a future mail.
>> >> >> >> Cheers >> >> >> >> FF >> >> >> >> On Thu, 8 Apr 2021 at 13:56, Manish Pandey2 via TF-A <tf-a@lists.trustedfirmware.org> wrote:
>> >> Hi, >> >> >> >> From TF-A project point of view, we prefer to use existingmechanism to pass parameters across boot stages using linked list of tagged elements (as suggested by Julius). It has support for both generic and SiP-specific tags. Having said that, it does not stop partners to introduce new mechanisms suitable for their usecase in platform port initially and later move to generic code if its suitable for other platforms.
>> >> >> >> To start with, Ampere can introduce a platform specificimplementation of memory tag(speed/NUMA topology etc) which can be evaluated and discussed for generalization in future. The tag will be populated in BL2 stage and can be forwarded to further stages(and to BL33) by passing the head of list pointer in one of the registers. Initially any register can be used but going forward a standardization will be needed.
>> >> >> >> The U-boot bloblist mentioned by Simon is conceptually similarto what TF-A is using, if there is consensus of using bloblist/taglist then TF-A tag list may be enhanced to take best of both the implementations.
>> >> >> >> One of the potential problems of having structure used indifferent projects is maintainability, this can be avoided by having a single copy of these structures in TF-A (kept inside "include/export" which intended to be used by other projects.)
>> >> >> >> Regarding usage of either UUID or tag, I echo the sentiments ofSimon and Julius to keep it simple and use tag values.
>> >> >> >> Looking forward to having further discussions on zoom calltoday.
>> >> >> >> Thanks >> >> Manish P >> >> >> >> ________________________________ >> >> From: TF-A <tf-a-bounces@lists.trustedfirmware.org> on behalfof Julius Werner via TF-A tf-a@lists.trustedfirmware.org
>> Sent: 25 March 2021 02:43 >> To: Simon Glass <sjg@chromium.org> >> Cc: Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>;Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> Just want to point out that TF-A currently already supports a(very simple) mechanism like this:
>> >> >> >>https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>> >>https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>> >>https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>> >> >> >> It's just a linked list of tagged elements. The tag space issplit into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31.
>> >> >> >> I would echo Simon's sentiment of keeping this as simple aspossible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once.
>> >> >> >> On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A <tf-a@lists.trustedfirmware.org> wrote:
>> >> Hi Harb, >> >> >> >> On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com> wrote:
>> >> Hello Folks, >> >> Appreciate the feedback and replies on this. Glad to see thatthere is interest in this topic.
>> >> >> >> I try to address the comments/feedback from Francois and Simonbelow….
>> >> >> >> @François Ozog – happy to discuss this on a zoom call. I willmake that time slot work, and will be available to attend April 8, 4pm CT.
>> >> >> >> Note that I’m using the term “HOB” here more generically, asthere are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases.
>> >> >> >> The whole point here is to provide mechanism to developfirmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM).
>> >> >> >> Keep in mind, in the server/datacenter market segment we arenot building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model:
>> >> “SoC” or “silicon” firmware – in TF-A this may map to BL1, BL2,BL31, and *possibly* one or more BL32 instances
>> “Platform” or “board” firmware – in TF-A this may map to BL33and *possibly* one or more BL32 instances.
>> >> >> >> Even the platform firmware stack could be further fragmented byhaving multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code.
>> >> >> >> To support a broad range of platform designs with a broad rangeof memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software.
>> >> >> >> I understand the versatility of DT, but I see two majorproblems with DT:
>> >> DT requires more complicated parsing to get properties, andeven more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained.
>> DT is probably overkill for this purpose – We really just wanta list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob)
>> >> >> >> I think that we should not mix the efforts around DT/ACPI specswith what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs).
>> >> >> >> Frankly, I would personally push back pretty hard on definingSMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls.
>> >> >> >> Please do let me know if you disagree and why. Look forward todiscussing on this thread or on the call.
>> >> >> >> @Simon Glass - Thanks for the pointer to bloblist. Ibriefly reviewed and it seems like a good baseline for what we may be looking for.
>> >> >> >> That being said, I would say that there is some benefit inhaving some kind of unique identifiers (e.g. UUID or some unique signature) so that we can tie standardized data structures (based on some future TBD specs) to a particular ID. For example, if the TPM driver in BL33 is looking for the TPM structure in the HOB/BOB list, and may not care about the other data blobs. The driver needs a way to identify and locate the blob it cares about.
>> >> >> >> The tag is intended to serve that purpose, although perhaps itshould switch from an auto-allocating enum to one with explicit values for each entry and a range for 'local' use.
>> >> >> >> I guess we can achieve this with the tag, but the problem withtag when you have eco-system with a lot of parties doing parallel development, you can end up with tag collisions and folks fighting about who has rights to what tag values. We would need some official process for folks to register tags for whatever new structures we define, or maybe some tag range for vendor specific structures. This comes with a lot of pain and bureaucracy. On the other hand, UUID has been a proven way to make it easy to just define your own blobs with *either* standard or vendor specific structures without worry of ID collisions between vendors.
>> >> >> >> True. I think the pain is overstated, though. In this case Ithink we actually want something that can be shared between projects and orgs, so some amount of coordination could be considered a benefit. It could just be a github pull request. I find the UUID unfriendly and not just to code size and eyesight! Trying to discover what GUIDs mean or are valid is quite tricky. E.g. see this code:
>> >> >> >> #define FSP_HOB_RESOURCE_OWNER_TSEG_GUID \ >> EFI_GUID(0xd038747c, 0xd00c, 0x4980, \ >> 0xb3, 0x19, 0x49, 0x01, 0x99, 0xa4, 0x7d, 0x55) >> >> (etc.) >> >> >> >> static struct guid_name { >> efi_guid_t guid; >> const char *name; >> } guid_name[] = { >> { FSP_HOB_RESOURCE_OWNER_TSEG_GUID, "TSEG" }, >> { FSP_HOB_RESOURCE_OWNER_FSP_GUID, "FSP" }, >> { FSP_HOB_RESOURCE_OWNER_SMM_PEI_SMRAM_GUID, "SMM PEI SMRAM"},
>> { FSP_NON_VOLATILE_STORAGE_HOB_GUID, "NVS" }, >> { FSP_VARIABLE_NV_DATA_HOB_GUID, "Variable NVS" }, >> { FSP_GRAPHICS_INFO_HOB_GUID, "Graphics info" }, >> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID1, "PCD databaseea" },
>> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID2, "PCD database9b" },
>> >> (never figured out what those two are) >> >> >> { FSP_HOB_RESOURCE_OWNER_PEIM_DXE_GUID, "PEIM Init DXE" }, >> { FSP_HOB_RESOURCE_OWNER_ALLOC_STACK_GUID, "Alloc stack" }, >> { FSP_HOB_RESOURCE_OWNER_SMBIOS_MEMORY_GUID, "SMBIOS memory"},
>> { {}, "zero-guid" }, >> {} >> }; >> >> static const char *guid_to_name(const efi_guid_t *guid) >> { >> struct guid_name *entry; >> >> for (entry = guid_name; entry->name; entry++) { >> if (!guidcmp(guid, &entry->guid)) >> return entry->name; >> } >> >> return NULL; >> } >> >> >> >> Believe it or not it took a fair bit of effort to find justthat small list, with nearly every one in a separate doc, from memory.
>> >> >> >> >> >> We can probably debate whether there is any value in GUID/UUIDor not during the call… but again, boblist seems like a reasonable starting point as an alternative to HOB.
>> >> >> >> Indeed. There is certainly value in both approaches. >> >> >> >> Regards, >> >> Simon >> >> >> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: François Ozog <francois.ozog@linaro.org> >> Sent: Tuesday, March 23, 2021 10:00 AM >> To: François Ozog <francois.ozog@linaro.org>; Ron Minnich <rminnich@google.com>; Paul Isaac's paul.isaacs@linaro.org
>> Cc: Simon Glass <sjg@chromium.org>; Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>; Boot Architecture Mailman List < boot-architecture@lists.linaro.org>; tf-a@lists.trustedfirmware.org
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> +Ron Minnich +Paul Isaac's >> >> >> >> Adding Ron and Paul because I think this interface should bealso benefiting LinuxBoot efforts.
>> >> >> >> On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A <tf-a@lists.trustedfirmware.org> wrote:
>> >> Hi, >> >> >> >> I propose we cover the topic at the next Trusted Substratezoom call on April 8th 4pm CET.
>> >> >> >> The agenda: >> >> ABI between non-secure firmware and the rest of firmware (EL3,S-EL1, S-EL2, SCP) to adapt hardware description to some runtime conditions.
>> >> runtime conditions here relates to DRAM size and topologydetection, secure DRAM memory carvings, PSCI and SCMI interface publishing.
>> >> >> >> For additional background on existing metadata: UEFI PlatformInitialization Specification Version 1.7, 5.5 Resource Descriptor HOB
>> >> Out of the ResourceType we care about isEFI_RESOURCE_SYSTEM_MEMORY.
>> >> This HOB lacks memory NUMA attachment or something that couldbe related to fill SRAT table for ACPI or relevant DT proximity domains.
>> >> HOB is not consistent accros platforms: some platforms (Arm)lists memory from the booting NUMA node, other platforms (x86) lists all memory from all NUMA nodes. (At least this is the case on the two platforms I tested).
>> >> >> >> There are two proposals to use memory structures from SPL/BLxup to the handover function (as defined in the Device Tree technical report) which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or EDK2.
>> >> I would propose we also discuss possibility of FF-A interfaceto actually query information or request actions to be done (this is a model actually used in some SoCs with proprietary SMC calls).
>> >> >> >> Requirements (to be validated): >> >> - ACPI and DT hardware descriptions. >> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot,TF-A/EDK2)
>> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot,TF-A/EDK2, TF-A/LinuxBoot)
>> >> - at least allows complete DRAM description and "persistent"usage (reserved areas for secure world or other usages)
>> >> - support secure world device assignment >> >> >> >> Cheers >> >> >> >> FF >> >> >> >> >> >> On Mon, 22 Mar 2021 at 19:56, Simon Glass <sjg@chromium.org>wrote:
>> >> Hi, >> >> Can I suggest using bloblist for this instead? It islightweight,
>> easier to parse, doesn't have GUIDs and is already used withinU-Boot
>> for passing info between SPL/U-Boot, etc. >> >> Docs here:https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist
>> Header file describes the format: >> https://github.com/u-boot/u-boot/blob/master/include/bloblist.h >> >> Full set of unit tests: >> https://github.com/u-boot/u-boot/blob/master/test/bloblist.c >> >> Regards, >> Simon >> >> On Mon, 22 Mar 2021 at 23:58, François Ozog <francois.ozog@linaro.org> wrote:
>> > >> > +Boot Architecture Mailman List <boot-architecture@lists.linaro.org>
>> > >> > standardization is very much welcomed here and need toaccommodate a very
>> > diverse set of situations. >> > For example, TEE OS may need to pass memory reservations toBL33 or
>> > "capture" a device for the secure world. >> > >> > I have observed a number of architectures: >> > 1) pass information from BLx to BLy in the form of a specificobject
>> > 2) BLx called by BLy by a platform specific SMC to getinformation
>> > 3) BLx called by BLy by a platform specific SMC to performDevice Tree
>> > fixups >> > >> > I also imagined a standardized "broadcast" FF-A call so thatany firmware
>> > element can either provide information or "do something". >> > >> > My understanding of your proposal is about standardizing onarchitecture 1)
>> > with the HOB format. >> > >> > The advantage of the HOB is simplicity but it may bedifficult to implement
>> > schemes such as pruning a DT because device assignment in thesecure world.
>> > >> > In any case, it looks feasible to have TF-A and OP-TEEcomplement the list
>> > of HOBs to pass information downstream (the bootflow). >> > >> > It would be good to start with building the comprehensivelist of
>> > information that need to be conveyed between firmwareelements:
>> > >> > information. | authoritative entity | reporting entity |information
>> > exchanged: >> > dram | TFA |TFA |
>> > <format to be detailed, NUMA topology to build the SRAT tableor DT
>> > equivalent?> >> > PSCI | SCP |TFA? |
>> > SCMI | SCP or TEE-OS | TFA? TEE-OS?| >> > secure SRAM | TFA. | TFA. | >> > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | >> > other? | | >> > | >> > >> > Cheers >> > >> > FF >> > >> > >> > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < >> > tf-a@lists.trustedfirmware.org> wrote: >> > >> > > Hello Folks, >> > > >> > > >> > > >> > > I'm emailing to start an open discussion about the adoptionof a concept
>> > > known as "hand-off blocks" or HOB to become a part of theTF-A Firmware
>> > > Framework Architecture (FFA). This is something that is apretty major
>> > > pain point when it comes to the adoption of TF-A in ARMServer SoC’s
>> > > designed to enable a broad range of highly configurabledatacenter
>> > > platforms. >> > > >> > > >> > > >> > > >> > > >> > > What is a HOB (Background)? >> > > >> > > --------------------------- >> > > >> > > UEFI PI spec describes a particular definition for how HOBmay be used for
>> > > transitioning between the PEI and DXE boot phases, which isa good
>> > > reference point for this discussion, but not necessarilythe exact solution
>> > > appropriate for TF-A. >> > > >> > > >> > > >> > > A HOB is simply a dynamically generated data structurepassed in between
>> > > two boot phases. This is information that was obtainedthrough discovery
>> > > and needs to be passed forward to the next boot phase*once*, with no API
>> > > needed to call back (e.g. no call back into previousfirmware phase is
>> > > needed to fetch this information at run-time - it is simplypassed one time
>> > > during boot). >> > > >> > > >> > > >> > > There may be one or more HOBs passed in between bootphases. If there are
>> > > more than one HOB that needs to be passed, this can be in aform of a "HOB
>> > > table", which (for example) could be a UUID indexed arrayof pointers to
>> > > HOB structures, used to locate a HOB of interest (based onUUID). In such
>> > > cases, instead of passing a single HOB, the boot phases mayrely on passing
>> > > the pointer to the HOB table. >> > > >> > > >> > > >> > > This has been extremely useful concept to employ on highlyconfigurable
>> > > systems that must rely on flexible discovery mechanisms toinitialize and
>> > > boot the system. This is especially helpful when you havemultiple
>> > > >> > > >> > > >> > > >> > > >> > > Why do we need HOBs in TF-A?: >> > > >> > > ----------------------------- >> > > >> > > It is desirable that EL3 firmware (e.g. TF-A) built for ARMServer SoC in
>> > > a way that is SoC specific *but* platform agnostic. Thismeans that a
>> > > single ARM SoC that a SiP may deliver to customers mayprovide a single
>> > > TF-A binary (e.g. BL1, BL2, BL31) that could be used tosupport a broad
>> > > range of platform designs and configurations in order toboot a platform
>> > > specific firmware (e.g. BL33 and possibly even BL32 code).In order to
>> > > achieve this, the platform configuration must be*discovered* instead of
>> > > statically compiled as it is today in TF-A via device treebased
>> > > enumeration. The mechanisms of discovery may differbroadly depending on
>> > > the relevant industry standard, or in some cases may haverely on SiP
>> > > specific discovery flows. >> > > >> > > >> > > >> > > For example: On server systems that support a broad rangeDIMM memory
>> > > population/topologies, all the necessary informationrequired to boot is
>> > > fully discovered via standard JEDEC Serial Presence Detect(SPD) over an
>> > > I2C bus. Leveraging the SPD bus, may platform variantscould be supported
>> > > with a single TF-A binary. Not only is this informationrequired to
>> > > initialize memory in early boot phases (e.g. BL2), thesubsequent boot
>> > > phases will also need this SPD info to construct a systemphysical address
>> > > map and properly initialize the MMU based on the memorypresent, and where
>> > > the memory may be present. Subsequent boot phases (e.g.BL33 / UEFI) may
>> > > need to generate standard firmware tables to the operatingsystems, such as
>> > > SMBIOS tables describing DIMM topology and various ACPItables (e.g. SLIT,
>> > > SRAT, even NFIT if NVDIMM's are present). >> > > >> > > >> > > >> > > In short, it all starts with a standardized or vendorspecific discovery
>> > > flow in an early boot stage (e.g. BL1/BL2), followed by thepassing of
>> > > information to the next boot stages (e.g. BL31/BL32/BL33). >> > > >> > > >> > > >> > > Today, every HOB may be a vendor specific structure, but inthe future
>> > > there may be benefit of defining standard HOBs. This maybe useful for
>> > > memory discovery, passing the system physical address map,enabling TPM
>> > > measured boot, and potentially many other common HOBuse-cases.
>> > > >> > > >> > > >> > > It would be extremely beneficial to the datacenter marketsegment if the
>> > > TF-A community would adopt this concept of informationpassing between all
>> > > boot phases as opposed to rely solely on device treeenumeration. This is
>> > > not intended to replace device tree, rather intended as analternative way
>> > > to describe the info that must be discovered anddynamically generated.
>> > > >> > > >> > > >> > > >> > > >> > > Conclusion: >> > > >> > > ----------- >> > > >> > > We are proposing that the TF-A community begin pursuing theadoption of
>> > > HOBs as a mechanism used for information exchange betweeneach boot stage
>> > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)?Longer term we
>> > > want to explore standardizing some HOB structures for theBL33 phase (e.g.
>> > > UEFI HOB structures), but initially would like to agree onthis being a
>> > > useful mechanism used to pass information between each bootstage.
>> > > >> > > >> > > >> > > Thanks, >> > > >> > > --Harb >> > > >> > > >> > > >> > > >> > > >> > > >> > > -- >> > > TF-A mailing list >> > > TF-A@lists.trustedfirmware.org >> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> > > >> > >> > >> > -- >> > François-Frédéric Ozog | *Director Linaro Edge & FogComputing Group*
>> > T: +33.67221.6485 >> > francois.ozog@linaro.org | Skype: ffozog >> > _______________________________________________ >> > boot-architecture mailing list >> > boot-architecture@lists.linaro.org >> > https://lists.linaro.org/mailman/listinfo/boot-architecture >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog ComputingGroup
>> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog ComputingGroup
>> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog ComputingGroup
>> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> > > -- > TF-A mailing list > TF-A@lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a
Hi,
On Fri, 11 Jun 2021 at 05:52, François Ozog francois.ozog@linaro.org wrote:
On Thu, 10 Jun 2021 at 23:57, Manish Pandey2 Manish.Pandey2@arm.com wrote:
Hi Everyone,
I have tried to conclude the discussions we had in two of the TF-A tech forum sessions and on mailing list.
The problem we are trying to solve is already solved in different projects in different ways, the purpose of these discussions was to come up with a standard way which can be adopted widely. Considering that many Firmware projects are not DT aware its better to avoid its usage and use simple C structures for wider acceptance. Based on the discussions following design came up as most acceptable solution
- Use list of pre-defined C data structures(blobs) to pass
information, let's call it bloblist
- Only bootloaders stages will participate
- Blobs will be identified by either tags or UUIDs
They always have a tag, but one of the tags can be BLOBLISTT_UUID
indicating it is for private use. But we should not allow this for passing across a boundary, so that no software needs to deal with UUID unless it is UEFI / private code. So, basically what Francios says below.
- Pass pointer to the bloblist head through x0
- Existing usage of x0 will be translated into a blob
After all discussions, I now support Simon proposal to use existing
bloblist: it does the job, is already upstream in key projects (core boot, U-Boot), is supported on x86 and Arm.
I would think of a few additions on the bloblist_rec:
struct bloblist_rec https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/bloblist_rec { u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 tag https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/tag; u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 hdr_size https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/hdr_size; u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 size; u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 spare https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/spare;};
enum bloblist_tag_t https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/bloblist_tag_t { BLOBLISTT_NONE https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_NONE = 0,
/* Vendor-specific tags are permitted here */ BLOBLISTT_EC_HOSTEVENT https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_EC_HOSTEVENT, /* Chromium OS EC host-event mask */
We can give these each a value (=1, =2) so it is clear.
BLOBLISTT_SPL_HANDOFF https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_SPL_HANDOFF, /* Hand-off info from SPL */ BLOBLISTT_VBOOT_CTX https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_VBOOT_CTX, /* Chromium OS verified boot context */ BLOBLISTT_VBOOT_HANDOFF https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_VBOOT_HANDOFF, /* Chromium OS internal handoff info */ /* * Advanced Configuration and Power Interface Global Non-Volatile * Sleeping table. This forms part of the ACPI tables passed to Linux. */ BLOBLISTT_ACPI_GNVS https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_ACPI_GNVS, BLOBLISTT_INTEL_VBT https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_INTEL_VBT, /* Intel Video-BIOS table */ BLOBLISTT_TPM2_TCG_LOG https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_TPM2_TCG_LOG, /* TPM v2 log space */ BLOBLISTT_TCPA_LOG https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_TCPA_LOG, /* TPM log space */ BLOBLISTT_ACPI_TABLES https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_ACPI_TABLES, /* ACPI tables for x86 */ BLOBLISTT_SMBIOS_TABLES https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_SMBIOS_TABLES, /* SMBIOS tables for x86 */
How about:
BLOBLISTT_LOCAL = 0xf0000000u /* values in this space are for local use during development */
BLOBLISTT_COUNT https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_COUNT};
I would add a BLOBLISTT_UUID for all proprietary things that people want to add. Using private space in a 64 bit field does not make the thing open. So by using this tag, we know exactly the nature of the blob. Negotiating for adding a new tag is a good open governance process.
+1
We may have to deal with super small SRAM (256KB) and thus we can assume the bloblist will be a single region of blobs. So I would add a BLOBLISTT_CONTINUATION which would be a pointer from the SRAM bloblist to a DRAM backed bloblist.
It is possible to relocate a bloblist, so I wonder if another approach would be to allow the bloblist to grow as it progresses through the boot (e.g. once SDRAM is available). That is what U-Boot does and it makes the code simpler (although only very slightly). However, it does introduce copying overhead...?
Other tags to consider: PSCI interface details, DRAM information, SCMI stuff, Secure SRAM and DRAM information...
- Going forward we would provide core changes to demonstrate this
design on various TF-A boundries, BL1<->BL2, BL2<->BL31 and BL31<->BL33(only BL31 part)
Please share your thoughts if you disagree to the proposed solution.
Also, refer to attached slide deck which was presented during last tech forum session on 3rd june, it also captures the points discussed during meeting and next steps for implementing it in TF-A.
Re devicetree, how about we use bloblist for simple things, but use a devicetree (perhaps in the bloblist) once SDRAM is available. Blobs that were created pre-SDRAM can continue to be passed on, but anything created after SDRAM is available should use devicetree? This would ensure that complex structures use devicetree rather than C structs, which are of course harder to extend / describe.
Regards, Simon
Thanks Manish Pandey
*From:* Joanna Farley Joanna.Farley@arm.com *Sent:* 02 June 2021 16:26 *To:* Madhukar Pappireddy Madhukar.Pappireddy@arm.com; Okash Khawaja < okash.khawaja@gmail.com>; Simon Glass sjg@chromium.org *Cc:* Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare < akhare@amperecomputing.com>; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com; tf-a@lists.trustedfirmware.org < tf-a@lists.trustedfirmware.org>; Manish Pandey2 Manish.Pandey2@arm.com *Subject:* Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
- TF-A list that got dropped (again)!
Joanna
*From: *Joanna Farley Joanna.Farley@arm.com *Date: *Wednesday, 2 June 2021 at 15:29 *To: *Madhukar Pappireddy Madhukar.Pappireddy@arm.com, Okash Khawaja < okash.khawaja@gmail.com>, Simon Glass sjg@chromium.org *Cc: *Harb Abdulhamid OS abdulhamid@os.amperecomputing.com, Boot Architecture Mailman List boot-architecture@lists.linaro.org, Ed Stuber edstuber@amperecomputing.com, Arjun Khare < akhare@amperecomputing.com>, U-Boot Mailing List u-boot@lists.denx.de, Paul Isaac's paul.isaacs@linaro.org, Ron Minnich rminnich@google.com, Moe Ammar moe@amperecomputing.com *Subject: *Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi Everyone,
The Manish Pandy and Madhukar Pappireddy of the TF-A team are planning to host another TF-A Tech Forum this Thursday to continue the live discussion.
Here is their agenda:
On tech forum this week, we would like to continue discussions on HOB list design.
The topics which we would like to cover is
- Evaluate different proposals of passing information through boot
phases.
- If we don't get an agreement on one solution fit for all then we would
try to get consensus for Infra segment platform(to solve original problem mentioned by Harb)
- Try to get an agreement on size of tags and how "hybrid and tag only"
HOB list can co-exist together?
Details of the call are:
======================
TF-A Tech Forum
When Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time
Calendar tf-a@lists.trustedfirmware.org
Who • Bill Fletcher- creator
• tf-a@lists.trustedfirmware.org
We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
Trusted Firmware is inviting you to a scheduled Zoom meeting.
Join Zoom Meeting
Meeting ID: 915 970 4974 <(915)%20970-4974>
One tap mobile
+16465588656 <(646)%20558-8656>,,9159704974 <(915)%20970-4974># US (New York)
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Dial by your location
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================
Joanna
On 19/05/2021, 03:50, "Madhukar Pappireddy" Madhukar.Pappireddy@arm.com wrote:
Attached slides presented by Manish in the TF-A tech forum. -----Original Message----- From: TF-A <tf-a-bounces@lists.trustedfirmware.org> On Behalf OfMadhukar Pappireddy via TF-A
Sent: Tuesday, May 18, 2021 8:59 PM To: Joanna Farley <Joanna.Farley@arm.com>; Okash Khawaja <okash.khawaja@gmail.com>; Simon Glass sjg@chromium.org
Cc: Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>; BootArchitecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare < akhare@amperecomputing.com>; U-Boot Mailing List u-boot@lists.denx.de; tf-a@lists.trustedfirmware.org; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs)for information passing between boot stages
Hi, I tried to summarize the discussions in the previous TF-A tech forumregarding the proposal to adopt Hand-off Blocks (HOBs) for passing information along the boot chain. I am certain I could not capture all suggestions/concerns brought up during the call. I apologize if I missed and/or misinterpreted any comments and would appreciate it if everyone could share their thoughts in response to this email thread.
The idea is to share information to other boot phases: > Dynamic information: Created during runtime. Shared in the form ofa chain of blobs(built as a linked list of C structure objects i.e., HOB list).
> Static information: Known at compile time. Historically, sharedthrough the use of Device Tree/ACPI tables
Both the above requirements are common in many ecosystems and need toco-exist.
There are broadly 3 problems to solve: 1. Format of HOB structures: It looks like the consensus is that wecould use existing mechanisms for this (BL_AUX_PARAM in TF-A or bloblist in u-boot).
2. Identification of HOB list entries: There is a debate aboutwhether tags would suffice or if the HOB list producer and consumer would depend on UUID/GUIDs for identifying a specific HOB structure. Another suggestion was to use a hybrid approach. Reserve a single tag ID for identifying/constructing a HOB structure that further leverages UUID based identifier. This way, the generic HOB list doesn't need to support UUIDs and can work with tags.
3. The design contract for the static interface between two bootphases: The problem at hand is whether to pass a pointer to a HOB list or a device tree blob through the general-purpose registers for configuration hand-off between two boot phases. Some proposals that came up:
> Proposal 1: Always pass a pointer to the device tree blobthrough the GP register and capture the pointer to the HOB list as a property of a node that is uniquely identifiable by the downstream boot phase. This needs to define a device tree binding such that producer and consumer agree on the information passed.
> Proposal 2: Pass a pointer to a generic container throughthe GP register that can be interpreted appropriately by both boot loaders(i.e., producer and consumer of the boot info). This container can either be a dtb or a HOB list which can be simply inferred by checking for a magic header that indicates if the buffer appears to be a flattened device tree.
> One another concern that was brought up offline is to makesure we don't break current design contracts between various boot loader phases in TF-A. Many of the general-purpose registers have a designated purpose such as to share configurations between BL images( such as firmware config dtb, SoC config dtb, Non trusted firmware config dtb, memory layout, entry point info, etc.).
If I am not mistaken, a single design may not fit the needs of everysegment(client, Infra, embedded) and the forum is open to solutions tailored for individual segments. Joanna will be sending a follow up email with more information about future TF-A tech forums that serves as a platform for further discussions.
Thanks, Madhukar -----Original Message----- From: TF-A <tf-a-bounces@lists.trustedfirmware.org> On Behalf OfJoanna Farley via TF-A
Sent: Sunday, May 16, 2021 5:19 AM To: Okash Khawaja <okash.khawaja@gmail.com>; Simon Glass <sjg@chromium.org>
Cc: Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>; BootArchitecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List < u-boot@lists.denx.de>; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs)for information passing between boot stages
Apologies I failed with the recording. Manish/Madhu will reply earlynext week with the slides and some notes to help with a follow up session which we hope to hold this Thursday. Invite and agenda will also be sent out early next week.
Thanks Joanna On 14/05/2021, 13:30, "TF-A on behalf of Okash Khawaja via TF-A" <tf-a-bounces@lists.trustedfirmware.org on behalf of tf-a@lists.trustedfirmware.org> wrote:
Hi, Do we have slides and video from last week's discussion? Thanks, Okash On Wed, May 5, 2021 at 11:52 PM Simon Glass via TF-A <tf-a@lists.trustedfirmware.org> wrote: > > Hi Harb, > > Thanks for the idea. I am still not completely sure whatbenefit UUID provides to an open project. I'd like to propose something different, more in the spirit of open collaboration. I also worry that the word 'standard' seems to be a synonym for UUIDs, UEFI, etc., i.e. enabling/preferring closed-source firmware and the continued decline of open-source projects. It really should not be.
> > So I suggest: Use simple integer IDs and reserve some area for'private' use. If you want to collaborate across projects outside your company, you either need to allocate a 'public' ID or agree privately between the parties which private ID to use.
> > This means that the default and easiest option is forcollaboration and a public ID, with private ones (whose purpose may be secret) reserved just for private use.
> > Regards, > Simon > > On Wed, 5 May 2021 at 11:42, Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com> wrote:
>> >> Hey Folks, >> >> We wanted to put out a middle-ground proposal to help guidethe discussion on the call tomorrow.
>> >> >> >> A proposal that we have been discussing offline involvesreserving a single tag ID for the purpose of construction UEFI PI HOB List structure, and that tag would be used to identify a HOB-specific structure that does leverage UUID based identifier. This will eliminate the burden of having to support UUID as the tag, and this enables projects that require UUID based identifiers for the broad range of HOB structures that need to be produced during the booting of the platform. Once we have a tag for a HOB list, this will enable various HOB producers that can add/extend the HOB list in TF-A code (or even pre-TF-A code), with a HOB consumer for that UUID/GUID on the other side (i.e. whatever the BL33 image is booting on that platform).
>> >> >> >> Essentially, the idea is if someone would like to support HOBstructures in a standard way using TF-A, they would wrap it up in a BL_AUX_PARAM/BLOB structure (whatever the group decides) and the way we identify the structure as a HOB list is with this new reserved tag.
>> >> >> >> Hopefully that makes sense and less contentious. Look forwardto discuss this further on the call.
>> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: Manish Pandey2 <Manish.Pandey2@arm.com> >> Sent: Friday, April 30, 2021 8:14 AM >> To: François Ozog <francois.ozog@linaro.org> >> Cc: Simon Glass <sjg@chromium.org>; Julius Werner <jwerner@chromium.org>; Harb Abdulhamid OS < abdulhamid@os.amperecomputing.com>; Boot Architecture Mailman List < boot-architecture@lists.linaro.org>; tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's < paul.isaacs@linaro.org>; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> Hi All, >> >> >> >> Please find invite for next TF-A Tech Forum session tocontinue our discussions on HOB implementation, feel free to forward it to others.
>> >> >> >> The next TF-A Tech Forum is scheduled for Thu 6th May 202116:00 – 17:00 (BST).
>> >> >> >> Agenda: >> >> Discussion Session: Static and Dynamic Information Handling inTF-A
>> >> Lead by Manish Pandey and Madhukar Pappireddy >> >> · There is ongoing mailing lists discussion[1] relatedwith adopting a mechanism to pass information through boot stages.
>> >> The requirement is two-fold: >> >> 1. Passing static information(config files) >> >> 2. Passing dynamic information (Hob list) >> >> In the upcoming TF-A tech forum, we can start with adiscussion on dynamic information passing and if time permits, we can cover static information passing. The purpose of the call is to have an open discussion and continue the discussion from the trusted-substrate call[2] done earlier. We would like to understand the various requirements and possible ways to implement it in TF-A in a generalized way so that it can work with other Firmware projects.
>> >> >> >> The two specific item which we would like to discuss are: >> >> 1. HOB format: TF-A/u-boot both has an existing bloblistimplementation, which uses tag values. Question, can this be enhanced to use hybrid values(Tag and UUID) both?
>> >> 2. Standardization on Physical register use to pass baseof HoB data structure.
>> >> References: >> >> [1]https://lists.trustedfirmware.org/pipermail/tf-a/2021-April/001069.html
>> >> [2]https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%
>> >> >> >> Thanks >> >> >> >> Joanna >> >> >> >> You have been invited to the following event. >> >> TF-A Tech Forum >> >> When >> >> Every 2 weeks from 16:00 to 17:00 on Thursday United KingdomTime
>> >> Calendar >> >> tf-a@lists.trustedfirmware.org >> >> Who >> >> • >> >> Bill Fletcher- creator >> >> • >> >> tf-a@lists.trustedfirmware.org >> >> more details » >> >> >> >> We run an open technical forum call for anyone to participateand it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
>> >> >> >> Feel free to forward this invite to colleagues. Invites arevia the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
>> >> >> >> Trusted Firmware is inviting you to a scheduled Zoom meeting. >> >> >> >> Join Zoom Meeting >> >> https://zoom.us/j/9159704974 >> >> >> >> Meeting ID: 915 970 4974 <(915)%20970-4974> >> >> >> >> One tap mobile >> >> +16465588656 <(646)%20558-8656>,,9159704974# US (New York) >> >> +16699009128 <(669)%20900-9128>,,9159704974# US (San Jose) >> >> >> >> Dial by your location >> >> +1 646 558 8656 <(646)%20558-8656> US (New York) >> >> +1 669 900 9128 <(669)%20900-9128> US (San Jose) >> >> 877 853 5247 <(877)%20853-5247> US Toll-free >> >> 888 788 0099 <(888)%20788-0099> US Toll-free >> >> Meeting ID: 915 970 4974 <(915)%20970-4974> >> >> Find your local number: https://zoom.us/u/ad27hc6t7h >> >> >> >> ________________________________ >> >> From: François Ozog <francois.ozog@linaro.org> >> Sent: 08 April 2021 16:50 >> To: Manish Pandey2 <Manish.Pandey2@arm.com> >> Cc: Simon Glass <sjg@chromium.org>; Julius Werner <jwerner@chromium.org>; Harb Abdulhamid OS < abdulhamid@os.amperecomputing.com>; Boot Architecture Mailman List < boot-architecture@lists.linaro.org>; tf-a@lists.trustedfirmware.org < tf-a@lists.trustedfirmware.org>; U-Boot Mailing List < u-boot@lists.denx.de>; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> Hi >> >> >> >> here is the meeting recording: >> >>https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%z
>> >> >> >> I am really sorry about the confusion related to the meetingtime. I have now understood: the Collaborate portal uses a specific calendar which is tied to US/Chicago timezone while the actual Google Calendar is tied to Central Europe timezone. I am going to drop the Collaborate portal and use a shared Google calendar (it should be visible on the trusted-substrate.org page).
>> >> >> >> I'll try to summarize what I learnt and highlight my view onwhat can be next steps in a future mail.
>> >> >> >> Cheers >> >> >> >> FF >> >> >> >> On Thu, 8 Apr 2021 at 13:56, Manish Pandey2 via TF-A <tf-a@lists.trustedfirmware.org> wrote:
>> >> Hi, >> >> >> >> From TF-A project point of view, we prefer to use existingmechanism to pass parameters across boot stages using linked list of tagged elements (as suggested by Julius). It has support for both generic and SiP-specific tags. Having said that, it does not stop partners to introduce new mechanisms suitable for their usecase in platform port initially and later move to generic code if its suitable for other platforms.
>> >> >> >> To start with, Ampere can introduce a platform specificimplementation of memory tag(speed/NUMA topology etc) which can be evaluated and discussed for generalization in future. The tag will be populated in BL2 stage and can be forwarded to further stages(and to BL33) by passing the head of list pointer in one of the registers. Initially any register can be used but going forward a standardization will be needed.
>> >> >> >> The U-boot bloblist mentioned by Simon is conceptually similarto what TF-A is using, if there is consensus of using bloblist/taglist then TF-A tag list may be enhanced to take best of both the implementations.
>> >> >> >> One of the potential problems of having structure used indifferent projects is maintainability, this can be avoided by having a single copy of these structures in TF-A (kept inside "include/export" which intended to be used by other projects.)
>> >> >> >> Regarding usage of either UUID or tag, I echo the sentimentsof Simon and Julius to keep it simple and use tag values.
>> >> >> >> Looking forward to having further discussions on zoom calltoday.
>> >> >> >> Thanks >> >> Manish P >> >> >> >> ________________________________ >> >> From: TF-A <tf-a-bounces@lists.trustedfirmware.org> on behalfof Julius Werner via TF-A tf-a@lists.trustedfirmware.org
>> Sent: 25 March 2021 02:43 >> To: Simon Glass <sjg@chromium.org> >> Cc: Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>;Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> Just want to point out that TF-A currently already supports a(very simple) mechanism like this:
>> >> >> >>https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>> >>https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>> >>https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>> >> >> >> It's just a linked list of tagged elements. The tag space issplit into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31.
>> >> >> >> I would echo Simon's sentiment of keeping this as simple aspossible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once.
>> >> >> >> On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A <tf-a@lists.trustedfirmware.org> wrote:
>> >> Hi Harb, >> >> >> >> On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com> wrote:
>> >> Hello Folks, >> >> Appreciate the feedback and replies on this. Glad to see thatthere is interest in this topic.
>> >> >> >> I try to address the comments/feedback from Francois and Simonbelow….
>> >> >> >> @François Ozog – happy to discuss this on a zoom call. I willmake that time slot work, and will be available to attend April 8, 4pm CT.
>> >> >> >> Note that I’m using the term “HOB” here more generically, asthere are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases.
>> >> >> >> The whole point here is to provide mechanism to developfirmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM).
>> >> >> >> Keep in mind, in the server/datacenter market segment we arenot building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model:
>> >> “SoC” or “silicon” firmware – in TF-A this may map to BL1,BL2, BL31, and *possibly* one or more BL32 instances
>> “Platform” or “board” firmware – in TF-A this may map to BL33and *possibly* one or more BL32 instances.
>> >> >> >> Even the platform firmware stack could be further fragmentedby having multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code.
>> >> >> >> To support a broad range of platform designs with a broadrange of memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software.
>> >> >> >> I understand the versatility of DT, but I see two majorproblems with DT:
>> >> DT requires more complicated parsing to get properties, andeven more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained.
>> DT is probably overkill for this purpose – We really just wanta list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob)
>> >> >> >> I think that we should not mix the efforts around DT/ACPIspecs with what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs).
>> >> >> >> Frankly, I would personally push back pretty hard on definingSMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls.
>> >> >> >> Please do let me know if you disagree and why. Look forwardto discussing on this thread or on the call.
>> >> >> >> @Simon Glass - Thanks for the pointer to bloblist. Ibriefly reviewed and it seems like a good baseline for what we may be looking for.
>> >> >> >> That being said, I would say that there is some benefit inhaving some kind of unique identifiers (e.g. UUID or some unique signature) so that we can tie standardized data structures (based on some future TBD specs) to a particular ID. For example, if the TPM driver in BL33 is looking for the TPM structure in the HOB/BOB list, and may not care about the other data blobs. The driver needs a way to identify and locate the blob it cares about.
>> >> >> >> The tag is intended to serve that purpose, although perhaps itshould switch from an auto-allocating enum to one with explicit values for each entry and a range for 'local' use.
>> >> >> >> I guess we can achieve this with the tag, but the problem withtag when you have eco-system with a lot of parties doing parallel development, you can end up with tag collisions and folks fighting about who has rights to what tag values. We would need some official process for folks to register tags for whatever new structures we define, or maybe some tag range for vendor specific structures. This comes with a lot of pain and bureaucracy. On the other hand, UUID has been a proven way to make it easy to just define your own blobs with *either* standard or vendor specific structures without worry of ID collisions between vendors.
>> >> >> >> True. I think the pain is overstated, though. In this case Ithink we actually want something that can be shared between projects and orgs, so some amount of coordination could be considered a benefit. It could just be a github pull request. I find the UUID unfriendly and not just to code size and eyesight! Trying to discover what GUIDs mean or are valid is quite tricky. E.g. see this code:
>> >> >> >> #define FSP_HOB_RESOURCE_OWNER_TSEG_GUID \ >> EFI_GUID(0xd038747c, 0xd00c, 0x4980, \ >> 0xb3, 0x19, 0x49, 0x01, 0x99, 0xa4, 0x7d, 0x55) >> >> (etc.) >> >> >> >> static struct guid_name { >> efi_guid_t guid; >> const char *name; >> } guid_name[] = { >> { FSP_HOB_RESOURCE_OWNER_TSEG_GUID, "TSEG" }, >> { FSP_HOB_RESOURCE_OWNER_FSP_GUID, "FSP" }, >> { FSP_HOB_RESOURCE_OWNER_SMM_PEI_SMRAM_GUID, "SMM PEISMRAM" },
>> { FSP_NON_VOLATILE_STORAGE_HOB_GUID, "NVS" }, >> { FSP_VARIABLE_NV_DATA_HOB_GUID, "Variable NVS" }, >> { FSP_GRAPHICS_INFO_HOB_GUID, "Graphics info" }, >> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID1, "PCD databaseea" },
>> { FSP_HOB_RESOURCE_OWNER_PCD_DATABASE_GUID2, "PCD database9b" },
>> >> (never figured out what those two are) >> >> >> { FSP_HOB_RESOURCE_OWNER_PEIM_DXE_GUID, "PEIM Init DXE" }, >> { FSP_HOB_RESOURCE_OWNER_ALLOC_STACK_GUID, "Alloc stack" }, >> { FSP_HOB_RESOURCE_OWNER_SMBIOS_MEMORY_GUID, "SMBIOSmemory" },
>> { {}, "zero-guid" }, >> {} >> }; >> >> static const char *guid_to_name(const efi_guid_t *guid) >> { >> struct guid_name *entry; >> >> for (entry = guid_name; entry->name; entry++) { >> if (!guidcmp(guid, &entry->guid)) >> return entry->name; >> } >> >> return NULL; >> } >> >> >> >> Believe it or not it took a fair bit of effort to find justthat small list, with nearly every one in a separate doc, from memory.
>> >> >> >> >> >> We can probably debate whether there is any value in GUID/UUIDor not during the call… but again, boblist seems like a reasonable starting point as an alternative to HOB.
>> >> >> >> Indeed. There is certainly value in both approaches. >> >> >> >> Regards, >> >> Simon >> >> >> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: François Ozog <francois.ozog@linaro.org> >> Sent: Tuesday, March 23, 2021 10:00 AM >> To: François Ozog <francois.ozog@linaro.org>; Ron Minnich <rminnich@google.com>; Paul Isaac's paul.isaacs@linaro.org
>> Cc: Simon Glass <sjg@chromium.org>; Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>; Boot Architecture Mailman List < boot-architecture@lists.linaro.org>; tf-a@lists.trustedfirmware.org
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> +Ron Minnich +Paul Isaac's >> >> >> >> Adding Ron and Paul because I think this interface should bealso benefiting LinuxBoot efforts.
>> >> >> >> On Tue, 23 Mar 2021 at 11:17, François Ozog via TF-A <tf-a@lists.trustedfirmware.org> wrote:
>> >> Hi, >> >> >> >> I propose we cover the topic at the next Trusted Substratezoom call on April 8th 4pm CET.
>> >> >> >> The agenda: >> >> ABI between non-secure firmware and the rest of firmware (EL3,S-EL1, S-EL2, SCP) to adapt hardware description to some runtime conditions.
>> >> runtime conditions here relates to DRAM size and topologydetection, secure DRAM memory carvings, PSCI and SCMI interface publishing.
>> >> >> >> For additional background on existing metadata: UEFI PlatformInitialization Specification Version 1.7, 5.5 Resource Descriptor HOB
>> >> Out of the ResourceType we care about isEFI_RESOURCE_SYSTEM_MEMORY.
>> >> This HOB lacks memory NUMA attachment or something that couldbe related to fill SRAT table for ACPI or relevant DT proximity domains.
>> >> HOB is not consistent accros platforms: some platforms (Arm)lists memory from the booting NUMA node, other platforms (x86) lists all memory from all NUMA nodes. (At least this is the case on the two platforms I tested).
>> >> >> >> There are two proposals to use memory structures from SPL/BLxup to the handover function (as defined in the Device Tree technical report) which can be U-boot (BL33 or just U-Boot in case of SPL/U-Boot scheme) or EDK2.
>> >> I would propose we also discuss possibility of FF-A interfaceto actually query information or request actions to be done (this is a model actually used in some SoCs with proprietary SMC calls).
>> >> >> >> Requirements (to be validated): >> >> - ACPI and DT hardware descriptions. >> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot,TF-A/EDK2)
>> >> - agnostic to boot framework (SPL/U-Boot, TF-A/U-Boot,TF-A/EDK2, TF-A/LinuxBoot)
>> >> - at least allows complete DRAM description and "persistent"usage (reserved areas for secure world or other usages)
>> >> - support secure world device assignment >> >> >> >> Cheers >> >> >> >> FF >> >> >> >> >> >> On Mon, 22 Mar 2021 at 19:56, Simon Glass <sjg@chromium.org>wrote:
>> >> Hi, >> >> Can I suggest using bloblist for this instead? It islightweight,
>> easier to parse, doesn't have GUIDs and is already used withinU-Boot
>> for passing info between SPL/U-Boot, etc. >> >> Docs here:https://github.com/u-boot/u-boot/blob/master/doc/README.bloblist
>> Header file describes the format: >>https://github.com/u-boot/u-boot/blob/master/include/bloblist.h
>> >> Full set of unit tests: >> https://github.com/u-boot/u-boot/blob/master/test/bloblist.c >> >> Regards, >> Simon >> >> On Mon, 22 Mar 2021 at 23:58, François Ozog <francois.ozog@linaro.org> wrote:
>> > >> > +Boot Architecture Mailman List <boot-architecture@lists.linaro.org>
>> > >> > standardization is very much welcomed here and need toaccommodate a very
>> > diverse set of situations. >> > For example, TEE OS may need to pass memory reservations toBL33 or
>> > "capture" a device for the secure world. >> > >> > I have observed a number of architectures: >> > 1) pass information from BLx to BLy in the form of aspecific object
>> > 2) BLx called by BLy by a platform specific SMC to getinformation
>> > 3) BLx called by BLy by a platform specific SMC to performDevice Tree
>> > fixups >> > >> > I also imagined a standardized "broadcast" FF-A call so thatany firmware
>> > element can either provide information or "do something". >> > >> > My understanding of your proposal is about standardizing onarchitecture 1)
>> > with the HOB format. >> > >> > The advantage of the HOB is simplicity but it may bedifficult to implement
>> > schemes such as pruning a DT because device assignment inthe secure world.
>> > >> > In any case, it looks feasible to have TF-A and OP-TEEcomplement the list
>> > of HOBs to pass information downstream (the bootflow). >> > >> > It would be good to start with building the comprehensivelist of
>> > information that need to be conveyed between firmwareelements:
>> > >> > information. | authoritative entity | reporting entity |information
>> > exchanged: >> > dram | TFA |TFA |
>> > <format to be detailed, NUMA topology to build the SRATtable or DT
>> > equivalent?> >> > PSCI | SCP |TFA? |
>> > SCMI | SCP or TEE-OS | TFA? TEE-OS?| >> > secure SRAM | TFA. | TFA. | >> > secure DRAM | TFA? TEE-OS? | TFA? TEE-OS? | >> > other? | | >> > | >> > >> > Cheers >> > >> > FF >> > >> > >> > On Mon, 22 Mar 2021 at 09:34, Harb Abdulhamid OS via TF-A < >> > tf-a@lists.trustedfirmware.org> wrote: >> > >> > > Hello Folks, >> > > >> > > >> > > >> > > I'm emailing to start an open discussion about theadoption of a concept
>> > > known as "hand-off blocks" or HOB to become a part of theTF-A Firmware
>> > > Framework Architecture (FFA). This is something that is apretty major
>> > > pain point when it comes to the adoption of TF-A in ARMServer SoC’s
>> > > designed to enable a broad range of highly configurabledatacenter
>> > > platforms. >> > > >> > > >> > > >> > > >> > > >> > > What is a HOB (Background)? >> > > >> > > --------------------------- >> > > >> > > UEFI PI spec describes a particular definition for how HOBmay be used for
>> > > transitioning between the PEI and DXE boot phases, whichis a good
>> > > reference point for this discussion, but not necessarilythe exact solution
>> > > appropriate for TF-A. >> > > >> > > >> > > >> > > A HOB is simply a dynamically generated data structurepassed in between
>> > > two boot phases. This is information that was obtainedthrough discovery
>> > > and needs to be passed forward to the next boot phase*once*, with no API
>> > > needed to call back (e.g. no call back into previousfirmware phase is
>> > > needed to fetch this information at run-time - it issimply passed one time
>> > > during boot). >> > > >> > > >> > > >> > > There may be one or more HOBs passed in between bootphases. If there are
>> > > more than one HOB that needs to be passed, this can be ina form of a "HOB
>> > > table", which (for example) could be a UUID indexed arrayof pointers to
>> > > HOB structures, used to locate a HOB of interest (based onUUID). In such
>> > > cases, instead of passing a single HOB, the boot phasesmay rely on passing
>> > > the pointer to the HOB table. >> > > >> > > >> > > >> > > This has been extremely useful concept to employ on highlyconfigurable
>> > > systems that must rely on flexible discovery mechanisms toinitialize and
>> > > boot the system. This is especially helpful when you havemultiple
>> > > >> > > >> > > >> > > >> > > >> > > Why do we need HOBs in TF-A?: >> > > >> > > ----------------------------- >> > > >> > > It is desirable that EL3 firmware (e.g. TF-A) built forARM Server SoC in
>> > > a way that is SoC specific *but* platform agnostic. Thismeans that a
>> > > single ARM SoC that a SiP may deliver to customers mayprovide a single
>> > > TF-A binary (e.g. BL1, BL2, BL31) that could be used tosupport a broad
>> > > range of platform designs and configurations in order toboot a platform
>> > > specific firmware (e.g. BL33 and possibly even BL32code). In order to
>> > > achieve this, the platform configuration must be*discovered* instead of
>> > > statically compiled as it is today in TF-A via device treebased
>> > > enumeration. The mechanisms of discovery may differbroadly depending on
>> > > the relevant industry standard, or in some cases may haverely on SiP
>> > > specific discovery flows. >> > > >> > > >> > > >> > > For example: On server systems that support a broad rangeDIMM memory
>> > > population/topologies, all the necessary informationrequired to boot is
>> > > fully discovered via standard JEDEC Serial Presence Detect(SPD) over an
>> > > I2C bus. Leveraging the SPD bus, may platform variantscould be supported
>> > > with a single TF-A binary. Not only is this informationrequired to
>> > > initialize memory in early boot phases (e.g. BL2), thesubsequent boot
>> > > phases will also need this SPD info to construct a systemphysical address
>> > > map and properly initialize the MMU based on the memorypresent, and where
>> > > the memory may be present. Subsequent boot phases (e.g.BL33 / UEFI) may
>> > > need to generate standard firmware tables to the operatingsystems, such as
>> > > SMBIOS tables describing DIMM topology and various ACPItables (e.g. SLIT,
>> > > SRAT, even NFIT if NVDIMM's are present). >> > > >> > > >> > > >> > > In short, it all starts with a standardized or vendorspecific discovery
>> > > flow in an early boot stage (e.g. BL1/BL2), followed bythe passing of
>> > > information to the next boot stages (e.g. BL31/BL32/BL33). >> > > >> > > >> > > >> > > Today, every HOB may be a vendor specific structure, butin the future
>> > > there may be benefit of defining standard HOBs. This maybe useful for
>> > > memory discovery, passing the system physical address map,enabling TPM
>> > > measured boot, and potentially many other common HOBuse-cases.
>> > > >> > > >> > > >> > > It would be extremely beneficial to the datacenter marketsegment if the
>> > > TF-A community would adopt this concept of informationpassing between all
>> > > boot phases as opposed to rely solely on device treeenumeration. This is
>> > > not intended to replace device tree, rather intended as analternative way
>> > > to describe the info that must be discovered anddynamically generated.
>> > > >> > > >> > > >> > > >> > > >> > > Conclusion: >> > > >> > > ----------- >> > > >> > > We are proposing that the TF-A community begin pursuingthe adoption of
>> > > HOBs as a mechanism used for information exchange betweeneach boot stage
>> > > (e.g. BL1->BL2, BL2->BL31, BL31->BL32, and BL31->BL33)?Longer term we
>> > > want to explore standardizing some HOB structures for theBL33 phase (e.g.
>> > > UEFI HOB structures), but initially would like to agree onthis being a
>> > > useful mechanism used to pass information between eachboot stage.
>> > > >> > > >> > > >> > > Thanks, >> > > >> > > --Harb >> > > >> > > >> > > >> > > >> > > >> > > >> > > -- >> > > TF-A mailing list >> > > TF-A@lists.trustedfirmware.org >> > > https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> > > >> > >> > >> > -- >> > François-Frédéric Ozog | *Director Linaro Edge & FogComputing Group*
>> > T: +33.67221.6485 >> > francois.ozog@linaro.org | Skype: ffozog >> > _______________________________________________ >> > boot-architecture mailing list >> > boot-architecture@lists.linaro.org >> > https://lists.linaro.org/mailman/listinfo/boot-architecture >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog ComputingGroup
>> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog ComputingGroup
>> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> -- >> TF-A mailing list >> TF-A@lists.trustedfirmware.org >> https://lists.trustedfirmware.org/mailman/listinfo/tf-a >> >> >> >> >> -- >> >> François-Frédéric Ozog | Director Linaro Edge & Fog ComputingGroup
>> >> T: +33.67221.6485 >> francois.ozog@linaro.org | Skype: ffozog >> >> > > -- > TF-A mailing list > TF-A@lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A@lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a-- François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* T: +33.67221.6485 francois.ozog@linaro.org | Skype: ffozog
Le jeu. 17 juin 2021 à 21:38, Simon Glass sjg@chromium.org a écrit :
Hi,
On Fri, 11 Jun 2021 at 05:52, François Ozog francois.ozog@linaro.org wrote:
On Thu, 10 Jun 2021 at 23:57, Manish Pandey2 Manish.Pandey2@arm.com wrote:
Hi Everyone,
I have tried to conclude the discussions we had in two of the TF-A tech forum sessions and on mailing list.
The problem we are trying to solve is already solved in different projects in different ways, the purpose of these discussions was to come up with a standard way which can be adopted widely. Considering that many Firmware projects are not DT aware its better to avoid its usage and use simple C structures for wider acceptance. Based on the discussions following design came up as most acceptable solution
- Use list of pre-defined C data structures(blobs) to pass
information, let's call it bloblist
- Only bootloaders stages will participate
- Blobs will be identified by either tags or UUIDs
They always have a tag, but one of the tags can be BLOBLISTT_UUID
indicating it is for private use. But we should not allow this for passing across a boundary, so that no software needs to deal with UUID unless it is UEFI / private code. So, basically what Francios says below.
- Pass pointer to the bloblist head through x0
- Existing usage of x0 will be translated into a blob
After all discussions, I now support Simon proposal to use existing
bloblist: it does the job, is already upstream in key projects (core boot, U-Boot), is supported on x86 and Arm.
I would think of a few additions on the bloblist_rec:
struct bloblist_rec https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/bloblist_rec { u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 tag https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/tag; u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 hdr_size https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/hdr_size; u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 size; u32 https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/u32 spare https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/spare;};
enum bloblist_tag_t https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/bloblist_tag_t { BLOBLISTT_NONE https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_NONE = 0,
/* Vendor-specific tags are permitted here */ BLOBLISTT_EC_HOSTEVENT https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_EC_HOSTEVENT, /* Chromium OS EC host-event mask */
We can give these each a value (=1, =2) so it is clear.
BLOBLISTT_SPL_HANDOFF https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_SPL_HANDOFF, /* Hand-off info from SPL */ BLOBLISTT_VBOOT_CTX https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_VBOOT_CTX, /* Chromium OS verified boot context */ BLOBLISTT_VBOOT_HANDOFF https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_VBOOT_HANDOFF, /* Chromium OS internal handoff info */ /* * Advanced Configuration and Power Interface Global Non-Volatile * Sleeping table. This forms part of the ACPI tables passed to Linux. */ BLOBLISTT_ACPI_GNVS https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_ACPI_GNVS, BLOBLISTT_INTEL_VBT https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_INTEL_VBT, /* Intel Video-BIOS table */ BLOBLISTT_TPM2_TCG_LOG https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_TPM2_TCG_LOG, /* TPM v2 log space */ BLOBLISTT_TCPA_LOG https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_TCPA_LOG, /* TPM log space */ BLOBLISTT_ACPI_TABLES https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_ACPI_TABLES, /* ACPI tables for x86 */ BLOBLISTT_SMBIOS_TABLES https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_SMBIOS_TABLES, /* SMBIOS tables for x86 */
How about:
BLOBLISTT_LOCAL = 0xf0000000u /* values in this space are for local use during development */
BLOBLISTT_COUNT https://elixir.bootlin.com/u-boot/latest/source/include/latest/C/ident/BLOBLISTT_COUNT};
I would add a BLOBLISTT_UUID for all proprietary things that people want to add. Using private space in a 64 bit field does not make the thing open. So by using this tag, we know exactly the nature of the blob. Negotiating for adding a new tag is a good open governance process.
+1
We may have to deal with super small SRAM (256KB) and thus we can assume the bloblist will be a single region of blobs. So I would add a BLOBLISTT_CONTINUATION which would be a pointer from the SRAM bloblist to a DRAM backed bloblist.
It is possible to relocate a bloblist, so I wonder if another approach would be to allow the bloblist to grow as it progresses through the boot (e.g. once SDRAM is available). That is what U-Boot does and it makes the code simpler (although only very slightly). However, it does introduce copying overhead...?
looks good: just making the problem.
Other tags to consider: PSCI interface details, DRAM information, SCMI stuff, Secure SRAM and DRAM information...
- Going forward we would provide core changes to demonstrate this
design on various TF-A boundries, BL1<->BL2, BL2<->BL31 and BL31<->BL33(only BL31 part)
Please share your thoughts if you disagree to the proposed solution.
Also, refer to attached slide deck which was presented during last tech forum session on 3rd june, it also captures the points discussed during meeting and next steps for implementing it in TF-A.
Re devicetree, how about we use bloblist for simple things, but use a devicetree (perhaps in the bloblist) once SDRAM is available. Blobs that were created pre-SDRAM can continue to be passed on, but anything created after SDRAM is available should use devicetree? This would ensure that complex structures use devicetree rather than C structs, which are of course harder to extend / describe.
+1
Regards, Simon
Thanks Manish Pandey
*From:* Joanna Farley Joanna.Farley@arm.com *Sent:* 02 June 2021 16:26 *To:* Madhukar Pappireddy Madhukar.Pappireddy@arm.com; Okash Khawaja < okash.khawaja@gmail.com>; Simon Glass sjg@chromium.org *Cc:* Harb Abdulhamid OS abdulhamid@os.amperecomputing.com; Boot Architecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare < akhare@amperecomputing.com>; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com; tf-a@lists.trustedfirmware.org < tf-a@lists.trustedfirmware.org>; Manish Pandey2 Manish.Pandey2@arm.com *Subject:* Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
- TF-A list that got dropped (again)!
Joanna
*From: *Joanna Farley Joanna.Farley@arm.com *Date: *Wednesday, 2 June 2021 at 15:29 *To: *Madhukar Pappireddy Madhukar.Pappireddy@arm.com, Okash Khawaja < okash.khawaja@gmail.com>, Simon Glass sjg@chromium.org *Cc: *Harb Abdulhamid OS abdulhamid@os.amperecomputing.com, Boot Architecture Mailman List boot-architecture@lists.linaro.org, Ed Stuber edstuber@amperecomputing.com, Arjun Khare < akhare@amperecomputing.com>, U-Boot Mailing List u-boot@lists.denx.de, Paul Isaac's paul.isaacs@linaro.org, Ron Minnich rminnich@google.com, Moe Ammar moe@amperecomputing.com *Subject: *Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs) for information passing between boot stages
Hi Everyone,
The Manish Pandy and Madhukar Pappireddy of the TF-A team are planning to host another TF-A Tech Forum this Thursday to continue the live discussion.
Here is their agenda:
On tech forum this week, we would like to continue discussions on HOB list design.
The topics which we would like to cover is
- Evaluate different proposals of passing information through boot
phases.
- If we don't get an agreement on one solution fit for all then we
would try to get consensus for Infra segment platform(to solve original problem mentioned by Harb)
- Try to get an agreement on size of tags and how "hybrid and tag only"
HOB list can co-exist together?
Details of the call are:
======================
TF-A Tech Forum
When Every 2 weeks from 16:00 to 17:00 on Thursday United Kingdom Time
Calendar tf-a@lists.trustedfirmware.org
Who • Bill Fletcher- creator
• tf-a@lists.trustedfirmware.org
We run an open technical forum call for anyone to participate and it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
Feel free to forward this invite to colleagues. Invites are via the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
Trusted Firmware is inviting you to a scheduled Zoom meeting.
Join Zoom Meeting
Meeting ID: 915 970 4974 <(915)%20970-4974>
One tap mobile
+16465588656 <(646)%20558-8656>,,9159704974 <(915)%20970-4974># US (New York)
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Dial by your location
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================
Joanna
On 19/05/2021, 03:50, "Madhukar Pappireddy" Madhukar.Pappireddy@arm.com wrote:
Attached slides presented by Manish in the TF-A tech forum. -----Original Message----- From: TF-A <tf-a-bounces@lists.trustedfirmware.org> On Behalf OfMadhukar Pappireddy via TF-A
Sent: Tuesday, May 18, 2021 8:59 PM To: Joanna Farley <Joanna.Farley@arm.com>; Okash Khawaja <okash.khawaja@gmail.com>; Simon Glass sjg@chromium.org
Cc: Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>; BootArchitecture Mailman List boot-architecture@lists.linaro.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare < akhare@amperecomputing.com>; U-Boot Mailing List u-boot@lists.denx.de; tf-a@lists.trustedfirmware.org; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs)for information passing between boot stages
Hi, I tried to summarize the discussions in the previous TF-A tech forumregarding the proposal to adopt Hand-off Blocks (HOBs) for passing information along the boot chain. I am certain I could not capture all suggestions/concerns brought up during the call. I apologize if I missed and/or misinterpreted any comments and would appreciate it if everyone could share their thoughts in response to this email thread.
The idea is to share information to other boot phases: > Dynamic information: Created during runtime. Shared in the form ofa chain of blobs(built as a linked list of C structure objects i.e., HOB list).
> Static information: Known at compile time. Historically, sharedthrough the use of Device Tree/ACPI tables
Both the above requirements are common in many ecosystems and needto co-exist.
There are broadly 3 problems to solve: 1. Format of HOB structures: It looks like the consensus is that wecould use existing mechanisms for this (BL_AUX_PARAM in TF-A or bloblist in u-boot).
2. Identification of HOB list entries: There is a debate aboutwhether tags would suffice or if the HOB list producer and consumer would depend on UUID/GUIDs for identifying a specific HOB structure. Another suggestion was to use a hybrid approach. Reserve a single tag ID for identifying/constructing a HOB structure that further leverages UUID based identifier. This way, the generic HOB list doesn't need to support UUIDs and can work with tags.
3. The design contract for the static interface between two bootphases: The problem at hand is whether to pass a pointer to a HOB list or a device tree blob through the general-purpose registers for configuration hand-off between two boot phases. Some proposals that came up:
> Proposal 1: Always pass a pointer to the device tree blobthrough the GP register and capture the pointer to the HOB list as a property of a node that is uniquely identifiable by the downstream boot phase. This needs to define a device tree binding such that producer and consumer agree on the information passed.
> Proposal 2: Pass a pointer to a generic container throughthe GP register that can be interpreted appropriately by both boot loaders(i.e., producer and consumer of the boot info). This container can either be a dtb or a HOB list which can be simply inferred by checking for a magic header that indicates if the buffer appears to be a flattened device tree.
> One another concern that was brought up offline is to makesure we don't break current design contracts between various boot loader phases in TF-A. Many of the general-purpose registers have a designated purpose such as to share configurations between BL images( such as firmware config dtb, SoC config dtb, Non trusted firmware config dtb, memory layout, entry point info, etc.).
If I am not mistaken, a single design may not fit the needs of everysegment(client, Infra, embedded) and the forum is open to solutions tailored for individual segments. Joanna will be sending a follow up email with more information about future TF-A tech forums that serves as a platform for further discussions.
Thanks, Madhukar -----Original Message----- From: TF-A <tf-a-bounces@lists.trustedfirmware.org> On Behalf OfJoanna Farley via TF-A
Sent: Sunday, May 16, 2021 5:19 AM To: Okash Khawaja <okash.khawaja@gmail.com>; Simon Glass <sjg@chromium.org>
Cc: Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>; BootArchitecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org; Ed Stuber edstuber@amperecomputing.com; Arjun Khare akhare@amperecomputing.com; U-Boot Mailing List < u-boot@lists.denx.de>; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com; Moe Ammar moe@amperecomputing.com
Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks (HOBs)for information passing between boot stages
Apologies I failed with the recording. Manish/Madhu will reply earlynext week with the slides and some notes to help with a follow up session which we hope to hold this Thursday. Invite and agenda will also be sent out early next week.
Thanks Joanna On 14/05/2021, 13:30, "TF-A on behalf of Okash Khawaja via TF-A" <tf-a-bounces@lists.trustedfirmware.org on behalf of tf-a@lists.trustedfirmware.org> wrote:
Hi, Do we have slides and video from last week's discussion? Thanks, Okash On Wed, May 5, 2021 at 11:52 PM Simon Glass via TF-A <tf-a@lists.trustedfirmware.org> wrote: > > Hi Harb, > > Thanks for the idea. I am still not completely sure whatbenefit UUID provides to an open project. I'd like to propose something different, more in the spirit of open collaboration. I also worry that the word 'standard' seems to be a synonym for UUIDs, UEFI, etc., i.e. enabling/preferring closed-source firmware and the continued decline of open-source projects. It really should not be.
> > So I suggest: Use simple integer IDs and reserve some area for'private' use. If you want to collaborate across projects outside your company, you either need to allocate a 'public' ID or agree privately between the parties which private ID to use.
> > This means that the default and easiest option is forcollaboration and a public ID, with private ones (whose purpose may be secret) reserved just for private use.
> > Regards, > Simon > > On Wed, 5 May 2021 at 11:42, Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com> wrote:
>> >> Hey Folks, >> >> We wanted to put out a middle-ground proposal to help guidethe discussion on the call tomorrow.
>> >> >> >> A proposal that we have been discussing offline involvesreserving a single tag ID for the purpose of construction UEFI PI HOB List structure, and that tag would be used to identify a HOB-specific structure that does leverage UUID based identifier. This will eliminate the burden of having to support UUID as the tag, and this enables projects that require UUID based identifiers for the broad range of HOB structures that need to be produced during the booting of the platform. Once we have a tag for a HOB list, this will enable various HOB producers that can add/extend the HOB list in TF-A code (or even pre-TF-A code), with a HOB consumer for that UUID/GUID on the other side (i.e. whatever the BL33 image is booting on that platform).
>> >> >> >> Essentially, the idea is if someone would like to support HOBstructures in a standard way using TF-A, they would wrap it up in a BL_AUX_PARAM/BLOB structure (whatever the group decides) and the way we identify the structure as a HOB list is with this new reserved tag.
>> >> >> >> Hopefully that makes sense and less contentious. Lookforward to discuss this further on the call.
>> >> >> >> Thanks, >> >> --Harb >> >> >> >> From: Manish Pandey2 <Manish.Pandey2@arm.com> >> Sent: Friday, April 30, 2021 8:14 AM >> To: François Ozog <francois.ozog@linaro.org> >> Cc: Simon Glass <sjg@chromium.org>; Julius Werner <jwerner@chromium.org>; Harb Abdulhamid OS < abdulhamid@os.amperecomputing.com>; Boot Architecture Mailman List < boot-architecture@lists.linaro.org>; tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's < paul.isaacs@linaro.org>; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> Hi All, >> >> >> >> Please find invite for next TF-A Tech Forum session tocontinue our discussions on HOB implementation, feel free to forward it to others.
>> >> >> >> The next TF-A Tech Forum is scheduled for Thu 6th May 202116:00 – 17:00 (BST).
>> >> >> >> Agenda: >> >> Discussion Session: Static and Dynamic Information Handlingin TF-A
>> >> Lead by Manish Pandey and Madhukar Pappireddy >> >> · There is ongoing mailing lists discussion[1]related with adopting a mechanism to pass information through boot stages.
>> >> The requirement is two-fold: >> >> 1. Passing static information(config files) >> >> 2. Passing dynamic information (Hob list) >> >> In the upcoming TF-A tech forum, we can start with adiscussion on dynamic information passing and if time permits, we can cover static information passing. The purpose of the call is to have an open discussion and continue the discussion from the trusted-substrate call[2] done earlier. We would like to understand the various requirements and possible ways to implement it in TF-A in a generalized way so that it can work with other Firmware projects.
>> >> >> >> The two specific item which we would like to discuss are: >> >> 1. HOB format: TF-A/u-boot both has an existing bloblistimplementation, which uses tag values. Question, can this be enhanced to use hybrid values(Tag and UUID) both?
>> >> 2. Standardization on Physical register use to pass baseof HoB data structure.
>> >> References: >> >> [1]https://lists.trustedfirmware.org/pipermail/tf-a/2021-April/001069.html
>> >> [2]https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%
>> >> >> >> Thanks >> >> >> >> Joanna >> >> >> >> You have been invited to the following event. >> >> TF-A Tech Forum >> >> When >> >> Every 2 weeks from 16:00 to 17:00 on Thursday United KingdomTime
>> >> Calendar >> >> tf-a@lists.trustedfirmware.org >> >> Who >> >> • >> >> Bill Fletcher- creator >> >> • >> >> tf-a@lists.trustedfirmware.org >> >> more details » >> >> >> >> We run an open technical forum call for anyone to participateand it is not restricted to Trusted Firmware project members. It will operate under the guidance of the TF TSC.
>> >> >> >> Feel free to forward this invite to colleagues. Invites arevia the TF-A mailing list and also published on the Trusted Firmware website. Details are here: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/
>> >> >> >> Trusted Firmware is inviting you to a scheduled Zoom meeting. >> >> >> >> Join Zoom Meeting >> >> https://zoom.us/j/9159704974 >> >> >> >> Meeting ID: 915 970 4974 <(915)%20970-4974> >> >> >> >> One tap mobile >> >> +16465588656 <(646)%20558-8656>,,9159704974# US (New York) >> >> +16699009128 <(669)%20900-9128>,,9159704974# US (San Jose) >> >> >> >> Dial by your location >> >> +1 646 558 8656 <(646)%20558-8656> US (New York) >> >> +1 669 900 9128 <(669)%20900-9128> US (San Jose) >> >> 877 853 5247 <(877)%20853-5247> US Toll-free >> >> 888 788 0099 <(888)%20788-0099> US Toll-free >> >> Meeting ID: 915 970 4974 <(915)%20970-4974> >> >> Find your local number: https://zoom.us/u/ad27hc6t7h >> >> >> >> ________________________________ >> >> From: François Ozog <francois.ozog@linaro.org> >> Sent: 08 April 2021 16:50 >> To: Manish Pandey2 <Manish.Pandey2@arm.com> >> Cc: Simon Glass <sjg@chromium.org>; Julius Werner <jwerner@chromium.org>; Harb Abdulhamid OS < abdulhamid@os.amperecomputing.com>; Boot Architecture Mailman List < boot-architecture@lists.linaro.org>; tf-a@lists.trustedfirmware.org < tf-a@lists.trustedfirmware.org>; U-Boot Mailing List < u-boot@lists.denx.de>; Paul Isaac's paul.isaacs@linaro.org; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> Hi >> >> >> >> here is the meeting recording: >> >>https://linaro-org.zoom.us/rec/share/zjfHeMIumkJhirLCVQYTHR6ftaqyWvF_0klgQnH... Passcode: IPn+5q%z
>> >> >> >> I am really sorry about the confusion related to the meetingtime. I have now understood: the Collaborate portal uses a specific calendar which is tied to US/Chicago timezone while the actual Google Calendar is tied to Central Europe timezone. I am going to drop the Collaborate portal and use a shared Google calendar (it should be visible on the trusted-substrate.org page).
>> >> >> >> I'll try to summarize what I learnt and highlight my view onwhat can be next steps in a future mail.
>> >> >> >> Cheers >> >> >> >> FF >> >> >> >> On Thu, 8 Apr 2021 at 13:56, Manish Pandey2 via TF-A <tf-a@lists.trustedfirmware.org> wrote:
>> >> Hi, >> >> >> >> From TF-A project point of view, we prefer to use existingmechanism to pass parameters across boot stages using linked list of tagged elements (as suggested by Julius). It has support for both generic and SiP-specific tags. Having said that, it does not stop partners to introduce new mechanisms suitable for their usecase in platform port initially and later move to generic code if its suitable for other platforms.
>> >> >> >> To start with, Ampere can introduce a platform specificimplementation of memory tag(speed/NUMA topology etc) which can be evaluated and discussed for generalization in future. The tag will be populated in BL2 stage and can be forwarded to further stages(and to BL33) by passing the head of list pointer in one of the registers. Initially any register can be used but going forward a standardization will be needed.
>> >> >> >> The U-boot bloblist mentioned by Simon is conceptuallysimilar to what TF-A is using, if there is consensus of using bloblist/taglist then TF-A tag list may be enhanced to take best of both the implementations.
>> >> >> >> One of the potential problems of having structure used indifferent projects is maintainability, this can be avoided by having a single copy of these structures in TF-A (kept inside "include/export" which intended to be used by other projects.)
>> >> >> >> Regarding usage of either UUID or tag, I echo the sentimentsof Simon and Julius to keep it simple and use tag values.
>> >> >> >> Looking forward to having further discussions on zoom calltoday.
>> >> >> >> Thanks >> >> Manish P >> >> >> >> ________________________________ >> >> From: TF-A <tf-a-bounces@lists.trustedfirmware.org> onbehalf of Julius Werner via TF-A tf-a@lists.trustedfirmware.org
>> Sent: 25 March 2021 02:43 >> To: Simon Glass <sjg@chromium.org> >> Cc: Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com>;Boot Architecture Mailman List boot-architecture@lists.linaro.org; tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org; U-Boot Mailing List u-boot@lists.denx.de; Paul Isaac's < paul.isaacs@linaro.org>; Ron Minnich rminnich@google.com
>> Subject: Re: [TF-A] Proposal: TF-A to adopt hand-off blocks(HOBs) for information passing between boot stages
>> >> >> >> Just want to point out that TF-A currently already supports a(very simple) mechanism like this:
>> >> >> >>https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>> >>https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>> >>https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...
>> >> >> >> It's just a linked list of tagged elements. The tag space issplit into TF-A-wide generic tags and SiP-specific tags (with plenty of room to spare if more areas need to be defined -- a 64-bit tag can fit a lot). This is currently being used by some platforms that run coreboot in place of BL1/BL2, to pass information from coreboot (BL2) to BL31.
>> >> >> >> I would echo Simon's sentiment of keeping this as simple aspossible and avoiding complicated and bloated data structures with UUIDs. You usually want to parse something like this as early as possible in the passed-to firmware stage, particularly if the structure encodes information about the debug console (like it does for the platforms I mentioned above). For example, in BL31 this basically means doing it right after moving from assembly to C in bl31_early_platform_setup2() to get the console up before running anything else. At that point in the BL31 initialization, the MMU and caches are disabled, so data accesses are pretty expensive and you don't want to spend a lot of parsing effort or calculate complicated checksums or the like. You just want something extremely simple where you ideally have to touch every data word only once.
>> >> >> >> On Wed, Mar 24, 2021 at 5:06 PM Simon Glass via TF-A <tf-a@lists.trustedfirmware.org> wrote:
>> >> Hi Harb, >> >> >> >> On Wed, 24 Mar 2021 at 11:39, Harb Abdulhamid OS <abdulhamid@os.amperecomputing.com> wrote:
>> >> Hello Folks, >> >> Appreciate the feedback and replies on this. Glad to seethat there is interest in this topic.
>> >> >> >> I try to address the comments/feedback from Francois andSimon below….
>> >> >> >> @François Ozog – happy to discuss this on a zoom call. Iwill make that time slot work, and will be available to attend April 8, 4pm CT.
>> >> >> >> Note that I’m using the term “HOB” here more generically, asthere are typically vendor specific structures beyond the resource descriptor HOB, which provides only a small subset of the information that needs to be passed between the boot phases.
>> >> >> >> The whole point here is to provide mechanism to developfirmware that we can build ARM Server SoC’s that support *any* BL33 payload (e.g. EDK2, AptioV, CoreBoot, and maybe even directly boot strapping LinuxBoot at some point). In other-words, we are trying to come up with a TF-A that would be completely agnostic to the implementation of BL33 (i.e. BL33 is built completely independently by a separate entity – e.g. an ODM/OEM).
>> >> >> >> Keep in mind, in the server/datacenter market segment we arenot building vertically integrated systems with a single entity compiling firmware/software stacks like most folks in TF-A have become use to. There are two categories of higher level firmware code blobs in the server/datacenter model:
>> >> “SoC” or “silicon” firmware – in TF-A this may map to BL1,BL2, BL31, and *possibly* one or more BL32 instances
>> “Platform” or “board” firmware – in TF-A this may map to BL33and *possibly* one or more BL32 instances.
>> >> >> >> Even the platform firmware stack could be further fragmentedby having multiple entities involved in delivering the entire firmware stack: IBVs, ODMs, OEMs, CSPs, and possibly even device vendor code.
>> >> >> >> To support a broad range of platform designs with a broadrange of memory devices, we need a crisp and clear contract between the SoC firmware that initializes memory (e.g. BL2) and how that platform boot firmware (e.g. BL33) gathers information about what memory that was initialized, at what speeds, NUMA topology, and many other relevant information that needs to be known and comprehended by the platform firmware and eventually by the platform software.
>> >> >> >> I understand the versatility of DT, but I see two majorproblems with DT:
>> >> DT requires more complicated parsing to get properties, andeven more complex to dynamically set properties – this HOB structures may need to be generated in boot phases where DDR is not available, and therefore we will be extremely memory constrained.
>> DT is probably overkill for this purpose – We really justwant a list of pointers to simple C structures that code cast (e.g. JEDEC SPD data blob)
>> >> >> >> I think that we should not mix the efforts around DT/ACPIspecs with what we are doing here, because those specs and concepts were developed for a completely different purpose (i.e. abstractions needed for OS / RTOS software, and not necessarily suitable for firmware-to-firmware hand-offs).
>> >> >> >> Frankly, I would personally push back pretty hard on definingSMC’s for something that should be one way information passing. Every SMC we add is another attack vector to the secure world and an increased burden on the folks that have to do security auditing and threat analysis. I see no benefit in exposing these boot/HOB/BOB structures at run-time via SMC calls.
>> >> >> >> Please do let me know if you disagree and why. Look forwardto discussing on this thread or on the call.
>> >> >> >> @Simon Glass - Thanks for the pointer to bloblist. Ibriefly reviewed and it seems like a goo
--
François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group* T: +33.67221.6485 francois.ozog@linaro.org | Skype: ffozog
boot-architecture@lists.linaro.org
-
François Ozog -
Joanna Farley -
Madhukar Pappireddy -
Manish Pandey2 -
Simon Glass