I took an action last week to provide a block of text for how
platforms without persistent variable storage should behave. Here's my
opening play:
Boot manager behaviour without persistent variable store
=======================================================
Platforms that do not implement persistent variable storage must
support the Removable Media Boot Behaviour as described by UEFI.
Such platforms can additionally implement support for additional
statically[1] defined images to be processed as SysPrep####,
Driver#### and Boot### global variable entries. If present, these
entries will be processed in the order specified by corresponding
statically defined SysPrepOrder, DriverOrder and BootOrder global
variables.
Any images referred to by such variables must reside in a
vendor-specific subdirectory on the EFI System Partition, as recorded
in http://uefi.org/registry. /BOOT must not be used except where
explicitly permitted by UEFI.
Where an executable is present in the prescribed Removable Media
location, boot of that must be attempted, and only after this fails
should any of the Boot#### entries be processed.
Statically configured BootNext, OsRecovery#### or PlatformRecovery####
entries must not be used.
[1] This is worth discussing, but if we were to support dynamic
creation of these, we need _very_ strict rules around it.
Hi
There is bit of discussion on linux-efi too , to handle DT update
I guess some members of this forum are active there too.
https://www.spinics.net/lists/linux-efi/msg13700.html
To summaries
1/ Ownership of DTB
IMO should be firmware and we should retain this
ownership in EBBR as well, Any objections/thoughts ?
Update
1/ Updating whole device tree from OS
[Capsule update can be used ]
2/ Just modifying the device tree DTBO
My preferred way to handle DTBO in firmware will be
https://source.android.com/devices/architecture/dto/multiple
See picture Runtime DTO implementation for multiple DTs
To store this information in partition, options we have
1/ Run time variables
2/ Some driver in Linux writing to DTBO partition
3/ Some other way ??
I am not sure, if distro are updating device tree which is default shipped with board ??
Thanks
Udit
Hi Abner,
Answers below...
On 27/04/2018 07:06, Chang, Abner (HPS SW/FW Technologist) wrote:
> Not sure if this mail list works or not.
>
> Hi Grant,
> GiIbert (from HPE, I think he is also in the mail list) and I are new to this discussion thread . Here are couple questions for you, your answer can give us the clear plan of EBBR spec.
>
> 1. I see EBBR spec on ARM web site, however seems it was released in last Sep. Any newer version of this spec?
As Dong said, there is no newer version of the spec. The copy on the Arm
website is only a draft release. The feedback we received on it was we
need a more open process for this spec; hence this group.
> 2. The purpose of EBBR is to standardize embedded system firmware on different processor archs and also intends abstract platform-specific implementations?
The purpose of EBBR is to standardize the firmware interface for
different platforms of the same architecture so that OS distributions
can support multiple boards. For example, the SUSE AArch64 image should
be able to boot on any EBBR compliant AArch64 platform (providing the
SoC is supported in the SUSE kernel).
Originally EBBR was only intended to address Arm platforms, but after
receiving interest from other architectures we've expanded the scope.
EBBR builds on existing specs, so it doesn't define a new firmware
interface. Rather, it starts with the UEFI spec and adds additional
requirements that are relevant for the embedded market.
> 3. EBBR aligns embedded SWF with UEFI spec (minimum requirements) and leverage EDK2 implementation on uBoot?
> 3-1 That is to use uBoot to initialize and boot system, but uBoot mimics UEFI protocols and EFI system table then boot to UEFI OS boot loader?
> 3-2 Or, Uboot could be one of EDK2 packages, wrap the necessary Uboot drivers into UEFI protocols (like the UEFI binding on top of uBoot) and build it using EDK2 build process then generate EDK2 format system firmware?
>
> 3-2 makes more sense to me but not sure which one is EBBR intention. I may have more question if the intention of EBBR is 3-2. :)
3-1 is the intent. EBBR specifies UEFI, but doesn't say anything about
implementation. U-Boot implements a subset of the UEFI spec which is
completely independed from EDK2/Tianocore. A vendor can produce an EBBR
compliant system using either U-Boot or EDK2/Tianocore.
The first release of EBBR (level 0) will specify a subset of UEFI
compliance. The intent is to reflect what is currently implemented in
the U-Boot project. Therefore, a vendor who is currently using U-Boot
firmware has an easy migration path to become EBBR compliant.
UEFI support in U-Boot is rapidly evolving, so I expect future revisions
of EBBR (level 1 and onwards) to require a larger subset of UEFI, with
the ultimate goal of being 100% compliant to the UEFI spec.
As you'll have gathered from the meeting, handling of persistent
variables is an important topic right now. The UEFI spec requires the
GetVariable()/SetVariable() runtime services to work, but U-Boot does
not yet have the ability to set variables at runtime. Similarly,
Tianocore/EDK2 on the 96Boards HiKey doesn't support setting variable at
all. Therefore, EBBR needs to define the behaviour of firmware when
SetVariable() does not work.
Cheers,
g.
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Hi folks,
Weekly EBBR meeting starts in about 1/2 hour. Dial in details below.
Once again the agenda is very short, but I'll open it up to other topics
after action item review. I think there was some interest in talking
about DT overlay handling.
Notes are being captured in the following Google doc. I would greatly
appreciate help with taking meeting minutes.
https://docs.google.com/document/d/1RdlFp5SIrvjcVOGoGEFVYDsqTqFBJHugbBMV5Mu…
Agenda:
1) Action item review
2) Any other business
Cheers,
g.
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*Notes from last week's meeting:Attendees: - Alex Graf (SUSE)- Ryan Harkin
(Linaro)- Rob Herring (Linaro)- Udit Kumar (NXP)- Grant Likely (Arm)- Leif
Lindholm (Linaro)- Bill Mills (TI)- Tom Rini- Peter Robinson (Redhat)-
Michal Simek (Xilinx)- Daniel Thompson (Linaro)- Dong Wei (Arm)Agenda: -
Action item review- [Grant] publish GitHub repo with EBBR text in
reStructuredText markup- [Dong] Get Arm legal approval to relicense and
publish EBBR- Other business- HW IP SharingAction
ItemsDateOwnerAction12-Apr-2018Grant & DongGet Arm legal approval to
relicense and publish EBBR19/04/2018: Approval in process, hope to have
answer by next week12-Apr-2018GrantPublish GitHub repo with EBBR text in
reStructuredText markup19/04/2018: Repo is created, but cannot publish
yet19-Apr-2018*new*BillWrite recommended policy for sharing HW between
firmware and OS19-Apr-2018*new*LeifDocument specification text for
platforms which do not support persistent variables, or do not support
runtime {Get,Set}Variable() NotesAction item review - Relicensing of EBBR
by ARM- Internal support is there, Grant is writing draft of legal texts-
“Should be done by next week” - ;-)- Github repo with current EBBR text in
reStructuredText- 50% complete- Repo is created and ready to roll but won’t
hit github until it is approved by Arm legal- Expect to use github wiki,
issue tracker, etc. At least for the short term.AOB - HW IP Sharing of
peripherals between OS and firmware- eMMC is a good example, I2C can be
another in some cases- Can EBBR help solve this issue?- Grant: One answer
could be: For any of these platforms a piece of hardware should have only
one master. If it is described in DT then OS has implicit permission to use
and abuse it.- Grant: EBBR should not dictate having anything resident in
the same exception level as the OS.- Udit: Seeking agreement that there are
some devices that need to be shared. EFI runtime variables is an especially
important case for EBBR- Bill: Base case is to agree with Grant… but…
firmware can expose services to allow a virtual device in Linux to access
features- Peter: Raspberry Pi has GPIO and ??? that is managed by the video
controller, accessed from kernel by a mailbox mechanism- Peter: Arm has
just released a new h/ware standard/recommendation to try and solve some of
these problems- Grant: What is scope of EBBR? Allows distros to support
embedded boards without cute embedded nonsense hacks. General device
sharing is not in scope.- Daniel: Agree with above… except for EFI runtime
variables which we would (or may) like EBBR to be able to rely on.- Grant:
Try to solve this in a wider space (UEFI forum) and then EBBR can inherit
the solution. - Bill: EFI runtime variables are easy if you have specific
hardware that is uniquely owned by firmware (NOR flash, etc).- What are
actions arising from this?- Ok not to have general solution- Action Bill
Mills: Document “something” about EFI variables for EBBR spec- Leif
(reluctantly) will look after take this to EFI forum (but not ready to go
to forum yet)- Device tree overlays- No common method of handling device
tree overlays- Peter: Alex G. and I discussed heavily at connect. Some
interest in solving this within grub since no need to push things down into
TianoCore/EDK2 and u-boot.- Alex: Have logic in firmware that can enumerate
“Hat”s and create EFI object for them. These objects could then be backed
by DTBOs - either by grabbing them from the device (EEPROM) or by a stored
blob in firmware. Grub for example could then also be taught about these
objects and DTBO support, so an OS could store its own overlays. EDK2 has
the hat logic support today and already does create objects.- Bill: FIT
handles this problem today… but also bundles in lots of other features. Not
clear how distros feel about this.- Tom: Let’s focus on what EBBR dictates
first!- Grant: Would like DT update to be part of EBBR but its not clear
whether overlay should be in scope at all.- Q: Where do we look to find out
what UEFI features u-boot supports today (Bill)- Alex: No exhaustive list
of present or absent features is available. To find what is missing “all”
we need to is run the SCT (self certification test) but u-boot isn’t quite
capable of running that quite yet (uefi shell, a prereq, is nearly there)-
Grant: What is list of platforms that are “good” for playing with EFI
features. RPi?- Alex: qemu is in good condition but many other choices-
Runtime variables- Daniel: If EBBR recommends no runtime variable then EBBR
must recommend a protocol for distros to adopt- Grant: EBBR will never
recommend no runtime variables… but it might allow it- Daniel: Agree… but
even allowing forces EBBR to recommend alternative- Action (Leif, also
reluctantly): Make this a bug and provide a recommendation*
On Thu, Apr 19, 2018 at 3:59 PM, Grant Likely <grant.likely(a)arm.com> wrote:
> Hi folks,
>
> Weekly EBBR meeting starts in about 1/2 hour. Dial in details below.
> Once again the agenda is very short, but I'll open it up to other topics
> after action item review. I think there was some interest in talking
> about DT overlay handling.
>
> Notes are being captured in the following Google doc. I would greatly
> appreciate help with taking meeting minutes.
>
> https://docs.google.com/document/d/1RdlFp5SIrvjcVOGoGEFVYDsq
> TqFBJHugbBMV5MuXUhw/edit?usp=sharing
>
> Agenda:
> 1) Action item review
> 2) Any other business
>
> Cheers,
> g.
>
Hi folks,
Next EBBR meeting is later today. Here is the agenda I have so far.
Please reply with action item status updates or other business
Agenda for this week's meeting:
- Status updates and action item review
- Behaviour without persistant variables
- DTB update policy/behaviour
- Any other business
As always, this Google doc will be used to capture notes. Please help
filling it in. You may need to request edit access if I haven't already
added you.
https://docs.google.com/document/d/1RdlFp5SIrvjcVOGoGEFVYDsqTqFBJHugbBMV5Mu…
---
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Here are the notes from yesterday’s meeting. Props to Daniel Thompson for taking notes!
Note: I didn’t capture the full list of attendees. If you were there, but aren’t in the list then let me know so I can add you to the official list. Eventually I’ll post these notes on a wiki for the project.
12 April 2018
Attendees
- Grant Likely (Arm)
- Ryan Harken (Linaro)
- Ruchika Gupta (NXP)
- Tom Rini (Konsulko)
- Peter Robinson (Red Hat)
- Alex Graf (SUSE)
- Daniel Thompson (Linaro)
- Ben Eckermann
(Incomplete list; Did not get full list of dial ins)
Agenda:
- Status and action item updates
- Other business
Notes:
Status
- No progress on legal issues to get things shared for outside contributions
- No progress on converting EBBR to sphinx document
Devicetree
- Committee meeting will shrink scope to cover governanceissues (process, release process, etc).
- Will be starting a regular technical sync up call soon
AOB
- EBBR and different architectures
- Alexander Graf has started talking among u-boot team about extending linuxefi support more widely
- Udit K: What to do about architectures that are not yet in UEFI?
# Grant: Not really in scope for EBBR, they should work with UEFI forum
- Grant: EBBR should be opt in (i.e. architecture representatives join us) rather then encompassing “everything”
- Udit K: What about big endian?
- Grant: Not UEFI… it merely looks like it.
- Tom: EBBR references other specifications, needs other specifications to take big endian before we move on it
- Udit K: How to handle devicetree updates?
- Grant: DT owned by platform is important, not discussed how to update it
- Grant: Should we create a DT specific section in EBBR?
- Udit K: Ideally, yes. We understand devicetree is owned by the platform but we have had better results using the devicetree in the kernel
- Peter: UEFI capsules?
- Alexander: Could use overlays to cope with difference between kernels
- Alexander: We cannot assume DTs will always be backwards compatible
- Grant: Historically have worked to ensure new kernels work with old devicetrees but not old kernels with new DTs
- Need to make sure firmware can always be recovered to a ‘safe’ state, and that DT updates don’t require reflashing the entire firmware.
Action: form sub team to draft DT update requirements.
When can others contribute?
- Expect to get things tidied up this week but the mailing list is open please discuss things here!
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.
Hi folks,
Weekly EBBR meeting starts in a few minutes. I'm expecting this one to be short. I've only got action item updates on the agenda, but Dong is still away and I haven't got a skeleton project posted yet. However, I'll open it up to other items that any of you want to discuss.
Cheers,
g.
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_______________________________________________
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https://lists.linaro.org/mailman/listinfo/boot-architecture
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Time: Every Thursday at 16:30-17:30 BST (8:30 PDT, 23:30 CST)
Join by Phone +44 2033215213,, 4664465#
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This is a weekly status call for the EBBR drafting process that came out
of a discussion at Linaro Connect HKG18 in March this year. As mentioned
in the notes[1] from that meeting, there is a desire to have EBBR
published in time for it to be used by an upcoming 96Boards
specification, due to be released in about 6 months time. This meeting
is a regular status update to track progress on EBBR development. I will
endeavour to keep it short when there isn’t much to discuss. I expect
initially there will be a lot to discuss to get the ball rolling, and
then will taper off.
Anyone is welcome to join. Feel free to pass this invitation along. Let
me know if anyone has trouble dialling/connecting to the SfB bridge.
[1]
https://lists.linaro.org/pipermail/boot-architecture/2018-April/000419.html
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This is a follow-up from the EBBR discussion that happened at Linaro Connect 2 weeks ago. As mentioned in the notes[1] from that meeting, there is a desire to have EBBR published in time for it to be used by an upcoming 96Boards specification, due to be released in about 6 months time. This meeting is a regular status update to track progress on EBBR development. I will endeavour to keep it short when there isn’t much to discuss. I expect initially there will be a lot to discuss to get the ball rolling.
Anyone is welcome to join. Feel free to pass this invitation along. Let me know if anyone has trouble dialling/connecting to the SfB bridge.
Time: Every Thursday at 16:30-17:30 BST (8:30 PDT, 23:30 CST)
[1] https://lists.linaro.org/pipermail/boot-architecture/2018-April/000419.html
g.
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