On 18/05/2018 17:45, Mark Brown wrote:
> On Fri, May 18, 2018 at 05:28:10PM +0100, Grant Likely wrote:
>
>> +Devicetree tables at the same time. Platforms that want to offer
>> +both ACPI and Devicetree solutions must implement a boot time
>> +mechanism to select one or the other, before the OS Loader is
>> +executed.
>
> How about "...must configure this using a mechanism that ensures that
> one or the other is chosen and provided to the OS loader when it is
> executed"? It doesn't really matter for sensible systems but I can see
> someone misreading the above and thinking there must be a prompt on boot
> or something, I do think this is me being paranoid about perverse
> implementors though.
>
My bikeshed now has a sign that reads:
+As stated above, EBBR systems must not provide both ACPI
+and Devicetree tables at the same time.
+Systems that support both interfaces must provide a configuration
+mechanism to select either ACPI or Devicetree,
+and must ensure only the selected interface is provided
+to the OS loader.
g.
On 18/05/2018 14:18, Tom Rini wrote:
> On Fri, May 18, 2018 at 02:06:08PM +0100, Grant Likely wrote:
>
>> Use reStructuredText citation markup to capture all referenced
>> documents. Sphinx will take care of creating a table of references at
>> the end of the document.
>>
>> Fixes #6
>> Signed-off-by: Grant Likely <grant.likely(a)arm.com>
> [snip]
>> @@ -132,22 +115,11 @@ This document defines the boot and runtime services that are expected by an
>> Operating System or hypervisor, for an ARM embedded device, which follows the
>> UEFI specification.
>>
>> -This document references the following specification and versions:
>> -
>> - UEFI 2.7
>> - Published June 2017, includes the AArch64 bindings.
>> -
>
> Is it clear enough when rendering the final document that here we don't
> need a link down to the UEFI reference?
Not sure what you mean. Can you elaborate?
I do think the introduction chapter needs to be reworked anyway to talk
about standardizing the firmware interface. It too quickly jumps to
"when UEFI is chosen", when what I'd rather it present is "here is a
standardized platform taylored to embedded systems"... and then get to
UEFI is part of that standard.
(it isn't about chosing UEFI; it is about choosing a standard platform)
>
>> This specification defines the boot and runtime services for a physical system,
>> including services that are required for virtualization.
>> It does not define a standardized abstract virtual machine view for a Guest
>> Operating System.
>>
>> -When present with in a system, this document makes additional references to the
>> -Power State Coordination Interface:
>> -
>> - PSCI 1.1
>> - Published April 2017.
>> -
> [snip]
>> @@ -306,9 +278,10 @@ command:
>>
>> - EfiWarmReset()
>>
>> -.. note:: When Runtime Services and PSCI co-exist, it is anticipated that
>> - Operating System calls to reset the system will go via Runtime Services and
>> - not directly to PSCI.
>> +.. note:: On platforms implementing the Power State Coordination Interface
>> + specification[PSCI_], it is still required that EBBR compliant
>> + Operating Systems calls to reset the system will go via Runtime Services
>> + and not directly to PSCI.
>>
>> Set Variable
>> ------------
>
> Is all of the above equivalent in terms of talking about PSCI? Thanks!
Ummm, yes? But I'm not sure that I understand what you're asking.
Thanks for the reviews on all the other patches.
g.
I'm adding some EBBR text around the CPU state at boot and I've lost
track of what is being done for multicore bringup. What is the current
state-of-the-art for multicore boot protocol when PSCI isn't available?
SBBR allows for the MP Boot Protocol; with the intend of phasing it out:
https://acpica.org/sites/acpica/files/MP%20Startup%20for%20ARM%20platforms.…
The kernel documents the spin table method:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tre…
What are the cool kids currently doing here?
g.
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On the weekly call today I suggested for people to assign issues to
themselves if they wanted to take it on. Turns out GitHub doesn't allow
that unless you've got write access to the project. So, if you want to
take on an issue, add a comment saying so and I'll send you an invite to
join the project.
Once you've accepted the invite I can assign issues to you.
g.
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Deferred probe will currently wait forever on dependent devices to probe,
but sometimes a driver will never exist. It's also not always critical for
a driver to exist. Platforms can rely on default configuration from the
bootloader or reset defaults for things such as pinctrl and power domains.
This is often the case with initial platform support until various drivers
get enabled. There's at least 2 scenarios where deferred probe can render
a platform broken. Both involve using a DT which has more devices and
dependencies than the kernel supports. The 1st case is a driver may be
disabled in the kernel config. The 2nd case is the kernel version may
simply not have the dependent driver. This can happen if using a newer DT
(provided by firmware perhaps) with a stable kernel version.
Unfortunately, this change breaks with modules as we have no way of
knowing when modules are done loading. One possibility is to make this
opt in or out based on compatible strings rather than at a subsystem level.
Ideally this information could be extracted automatically somehow. OTOH,
maybe the lists are pretty small. There's only a handful of subsystems
that can be optional, and then only so many drivers in those that can be
modules (at least for pinctrl, many drivers are built-in only).
Cc: Alexander Graf <agraf(a)suse.de>
Signed-off-by: Rob Herring <robh(a)kernel.org>
---
This patch came out of a discussion on the ARM boot-architecture
list[1] about DT forwards and backwards compatibility issues. There are
issues with newer DTs breaking on older, stable kernels. Some of these
are difficult to solve, but cases of optional devices not having
kernel support should be solvable.
I tested this on a RPi3 B with the pinctrl driver forced off. With this
change, the MMC/SD and UART drivers can function without the pinctrl
driver.
Rob
[1] https://lists.linaro.org/pipermail/boot-architecture/2018-April/000466.html
drivers/base/dd.c | 16 ++++++++++++++++
drivers/pinctrl/devicetree.c | 2 +-
include/linux/device.h | 2 ++
3 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index c9f54089429b..5848808b9d7a 100644
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -226,6 +226,15 @@ void device_unblock_probing(void)
driver_deferred_probe_trigger();
}
+
+int driver_deferred_probe_optional(void)
+{
+ if (initcalls_done)
+ return -ENODEV;
+
+ return -EPROBE_DEFER;
+}
+
/**
* deferred_probe_initcall() - Enable probing of deferred devices
*
@@ -240,6 +249,13 @@ static int deferred_probe_initcall(void)
/* Sort as many dependencies as possible before exiting initcalls */
flush_work(&deferred_probe_work);
initcalls_done = true;
+
+ /*
+ * Trigger deferred probe again, this time we won't defer anything
+ * that is optional
+ */
+ driver_deferred_probe_trigger();
+ flush_work(&deferred_probe_work);
return 0;
}
late_initcall(deferred_probe_initcall);
diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c
index b601039d6c69..096e52a5c506 100644
--- a/drivers/pinctrl/devicetree.c
+++ b/drivers/pinctrl/devicetree.c
@@ -120,7 +120,7 @@ static int dt_to_map_one_config(struct pinctrl *p,
np_config);
of_node_put(np_pctldev);
/* OK let's just assume this will appear later then */
- return -EPROBE_DEFER;
+ return driver_deferred_probe_optional();
}
/* If we're creating a hog we can use the passed pctldev */
if (pctldev && (np_pctldev == p->dev->of_node))
diff --git a/include/linux/device.h b/include/linux/device.h
index 0059b99e1f25..8de920442bc1 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -332,6 +332,8 @@ struct device *driver_find_device(struct device_driver *drv,
struct device *start, void *data,
int (*match)(struct device *dev, void *data));
+int driver_deferred_probe_optional(void);
+
/**
* struct subsys_interface - interfaces to device functions
* @name: name of the device function
--
2.17.0
I've started tracking EBBR issues in github, so I will no longer track
them in the weekly meeting notes document. Please go take a look. Feel
free to add issues for things that need to be done, or comment on the
items that are there.
Better yet, write patches to fix the existing issues! ;-)
https://github.com/ARM-software/ebbr/issues
Cheers,
g.
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Replace the LICENSE file with the full text of CC-BY-SA 4.0 License into
the LICENSE file, and move the DCO description into the README.
The LICENSE file is a verbatim copy of:
https://creativecommons.org/licenses/by-sa/4.0/legalcode.txt
Signed-off-by: Grant Likely <grant.likely(a)arm.com>
---
LICENSE | 428 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
LICENSE.rst | 50 -------
README.rst | 75 ++++++++---
3 files changed, 488 insertions(+), 65 deletions(-)
create mode 100644 LICENSE
delete mode 100644 LICENSE.rst
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..fe8dbc5
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,428 @@
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diff --git a/LICENSE.rst b/LICENSE.rst
deleted file mode 100644
index 78313a4..0000000
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@@ -1,50 +0,0 @@
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- Developer Certificate of Origin
- Version 1.1
-
- Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
- 1 Letterman Drive
- Suite D4700
- San Francisco, CA, 94129
-
- Everyone is permitted to copy and distribute verbatim copies of this
- license document, but changing it is not allowed.
-
-
- Developer's Certificate of Origin 1.1
-
- By making a contribution to this project, I certify that:
-
- (a) The contribution was created in whole or in part by me and I
- have the right to submit it under the open source license
- indicated in the file; or
-
- (b) The contribution is based upon previous work that, to the best
- of my knowledge, is covered under an appropriate open source
- license and I have the right under that license to submit that
- work with modifications, whether created in whole or in part
- by me, under the same open source license (unless I am
- permitted to submit under a different license), as indicated
- in the file; or
-
- (c) The contribution was provided directly to me by some other
- person who certified (a), (b) or (c) and I have not modified
- it.
-
- (d) I understand and agree that this project and the contribution
- are public and that a record of the contribution (including all
- personal information I submit with it, including my sign-off) is
- maintained indefinitely and may be redistributed consistent with
- this project or the open source license(s) involved.
diff --git a/README.rst b/README.rst
index 84aeb0a..1babcf4 100644
--- a/README.rst
+++ b/README.rst
@@ -13,11 +13,21 @@ expected in September 2018. You can find the current draft text in this
repository, but be aware that everything in the draft text is subject to
change before an official v1.0 release is published.
-The documentation in this project is provided under the terms of the
-Creative Commons Attribution Share-Alike License.
-Licensing details can be found in the LICENSE.rst_ file.
+License
+=======
-.. _LICENSE.rst: ./LICENSE.rst
+This work is licensed under the Creative Commons Attribution-ShareAlike 4.0
+International License. To view a copy of this license, visit
+http://creativecommons.org/licenses/by-sa/4.0/ or send a letter to
+Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.
+
+A copy of the license is included in the LICENSE_ file.
+
+.. image:: https://i.creativecommons.org/l/by-sa/4.0/88x31.png
+ :target: http://creativecommons.org/licenses/by-sa/4.0/
+ :alt: Creative Commons License
+
+.. _LICENSE: ./LICENSE
Contributing
============
@@ -25,29 +35,64 @@ Contributing
Master copy of this project is hosted on GitHub:
https://github.com/ARM-software/ebbr
-Anyone may contribute to EBBR. Contributions must be made with a
-Developer Certificate of Origin (DCO_) attestation that the contribution
-confirms to the license of the project. The attestation is made by the
-developer including a ``Signed-off-by: <email-address>`` tag in the
-commit text of the contribution.
-
-EBBR discussion is on the boot-architecture_ and arm.ebbr-discuss mailing lists.
-The 'official' list is arm.ebbr-discuss, but the list archives are not yet public,
-so boot-architecture_ is being used to keep everything in the open.
+Anyone may contribute to the EBBR project. EBBR discussion uses the
+boot-architecture_ and arm.ebbr-discuss mailing lists.
+The 'official' list is arm.ebbr-discuss, but the list archives are not
+yet public, so boot-architecture_ is being used to keep everything in
+the open.
* boot-architechture(a)lists.linaro.org
* arm.ebbr-discuss(a)arm.com
-Past discussions can be found in the _boot-architecture-archive.
+Past discussions can be found in the boot-architecture-archive_.
+
+To help track the origin of contributions, this project uses the same
+DCO_ "sign-off" process as used by the Linux kernel.
+The sign-off is a simple line at the end of the explanation for the
+patch, which certifies that you wrote it or otherwise have the right to
+pass it on as an open-source patch. The rules are pretty simple: if you
+can certify the below:
+
+Developer's Certificate of Origin 1.1
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+By making a contribution to this project, I certify that:
+
+ (a) The contribution was created in whole or in part by me and I
+ have the right to submit it under the open source license
+ indicated in the file; or
+
+ (b) The contribution is based upon previous work that, to the best
+ of my knowledge, is covered under an appropriate open source
+ license and I have the right under that license to submit that
+ work with modifications, whether created in whole or in part
+ by me, under the same open source license (unless I am
+ permitted to submit under a different license), as indicated
+ in the file; or
+
+ (c) The contribution was provided directly to me by some other
+ person who certified (a), (b) or (c) and I have not modified
+ it.
+
+ (d) I understand and agree that this project and the contribution
+ are public and that a record of the contribution (including all
+ personal information I submit with it, including my sign-off) is
+ maintained indefinitely and may be redistributed consistent with
+ this project or the open source license(s) involved.
+
+then you just add a line saying::
+
+ Signed-off-by: Random J Developer <random(a)developer.example.org>
IRC Channel: ``#ebbr`` on ofct
.. _DCO: https://developercertificate.org/
.. _boot-architecture: https://lists.linaro.org/mailman/listinfo/boot-architecture
-.. _boot-architecture-archive: https://lists.linaro.org/pipermail/boot-architecture/
+.. _boot-architecture-archive: https://lists.linaro.org/pipermail/boot-architecture
Writers Guide
=============
+
All documentation in this repository uses reStructuredText_ markup
with Sphinx_ extensions.
--
2.13.0
Hi folks,
Internal approval for EBBR has come through and we now have a GitHub
repo. It's empty at the moment, but I'll be pushing the current EBBR
text there shortly once I've fixed the license text.
License will be CC-BY-SA
https://github.com/ARM-software/ebbr
We can start using this page to track issue. I'll put all the active
action items into github issues.
Cheers,
g.
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.
[explicitly cc'ing boot-arch to see if this solves the TI auth problems]
On 05/04/2018 11:45 AM, Alexander Graf wrote:
> On 05/04/2018 04:56 PM, Grant Likely wrote:
>> On 04/05/2018 15:46, Grant Likely wrote:
>>> On 03/05/2018 09:43, Daniel Thompson wrote:
>>>> On Wed, May 02, 2018 at 06:09:15PM -0400, Tom Rini wrote:
>>>>> On Wed, May 02, 2018 at 10:48:11PM +0100, Grant Likely wrote:
>>>>>> On 02/05/2018 22:24, Tom Rini wrote:
>>>>>>> On Wed, May 02, 2018 at 08:40:42PM +0100, Daniel Thompson wrote:
>>>>>>>>
>>>>>>>> In terms of the restrictions that come from EBBR mandating GPT:
>>>>>>>
>>>>>>> Can we step back, why is EBBR mandating GPT?
>>>>>>
>>>>>> I think EBBR should recommend GPT, but allow MBR if the SoC boot
>>>>>> masked
>>>>>> rom conflicts with GPT.
>>>>>>
>>>>>> In the early days of GPT there was also a hybrid GPT+MBR scheme that
>>>>>> could list the boot partition in the MBR, but still have a full
>>>>>> GPT. It
>>>>>> isn't pretty, but there is precidence.
>>>>>
>>>>> How about recommends GPT but allows MBR, no qualifiers. As you note
>>>>> there's a lot of ways to fiddle around and make it work, probably, on
>>>>> all of the existing SoCs that do magic offsets. But it's a lot easier
>>>>> to just allow MBR (what the SoCs were designed to have to live
>>>>> with) and
>>>>> guide line that in this case nothing before the first 2MiB be used by
>>>>> the OS. With a few more spec words around all of that so it's nice
>>>>> and
>>>>> formal :)
>>>>
>>>> I'm OK to allow MBR.
>>>>
>>>> I'd be inclined to require that protective partitions be used to defend
>>>> the first 2MB though. They are more flexible and are a useful hint to
>>>> anyone trying to manually partition.
>>>>
>>>>
>>>> In a different mail Tom wrote:
>>>>> And I agree with the high level idea of needing to do something to
>>>>> protect systems with a magic in-use spot.
>>>>
>>>> There are a couple of extra details.
>>>>
>>>> 1. We can't allocate a GUID to discourage an automatic partitioner
>>>> from harming a protected partition. We only have the 8-bit
>>>> partition type.
>>>> Some potential candidates could be 0xA2 (which Altera appear use
>>>> for a similar purpose), 0xE7 (wikipedia does not report existing
>>>> uses) or 0xF0 (PA-RISC Linux boot loader).
>>>>
>>>> 2. Boot ROMs that have built-in support for FAT could be hard coded to
>>>> require a specific partition type. >
>>>> I think we don't need to worry about #2 to much: systems with built-in
>>>> MBR/FAT parsing can use hybrid MBR/GPT to communicate to distros
>>>> which partitions are protected because (presumably) they allow
>>>> flexibility in placing the first sector of the FAT partition.
>>>
>>> Can we start a list of SoCs that have special requirements on the
>>> boot eMMC/SD/USB? It would be useful to see the cross-section of
>>> requirements.
>>>
>>> I've created a wiki page to start capturing data. From their we can
>>> decide what scenarios the spec needs to cover.
>>>
>>> https://github.com/glikely/ebbr-for-discussion/wiki/Boot-Media-Behaviour
>>
>> One more thought, are there many new SoCs still using hard coded
>> offsets instead of an MBR or GPT? It may be that there aren't enough
>> left for us to care about for EBBR level 0. In which case EBBR Level 0
>> should support both MBR and GPT (non-hybrid), and then narrow to GPT
>> only in a future revision.
>
> I don't think we'll be able to move away from MBR anytime soon. For a
> quick glimpse on what SoCs need to have blobs installed where, take a
> look at our image creation script:
>
> https://build.opensuse.org/package/view_file/openSUSE:Factory:ARM:Live/JeOS…
>
>
> There you can see that we force to MBR (for various reasons) on:
>
> * RPi (reads MBR)
> * i.MX 5x/6 (SPL at sector 2)
> * Exynos 4/5 (SPL is in sector 1, not sure about newer ones)
> * AM905 (SPL in sector 1)
> * Kirkwood (SPL in sector 1)
> * Zynq(MP) (convenient to store boot.bin on FAT partition in MBR)
>
> I think we should simply dictate that EBBR compliant OSs do not start
> any partitions before a sane boundary (1MB? 2MB?). IIRC most
> partitioning tools these days won't start partitions before 1MB anyway,
> so if we declare 1MB a safe bound we essentially have no work to do.
>
>
I did skim (not study) the script. Looks like a good resource of
current board info. I see you are using raw mode for many boards.
I am missing something. If there is only MBR and no GPT then there is
no GUID type for EFI Partition. So how does the firmware find the "EFI
Partition" and the default /efi/boot/boot*.efi file? Does it just use
the partition with boot flag?
On 04/05/2018 16:00, Tom Rini wrote:
> On Fri, May 04, 2018 at 03:46:52PM +0100, Grant Likely wrote:
[...]
>> Can we start a list of SoCs that have special requirements on the boot
>> eMMC/SD/USB? It would be useful to see the cross-section of requirements.
>>
>> I've created a wiki page to start capturing data. From their we can
>> decide what scenarios the spec needs to cover.
>>
>> https://github.com/glikely/ebbr-for-discussion/wiki/Boot-Media-Behaviour
>
> I'm not sure if there's a button somewhere to allow more widely used
> editing of the wiki part of github. Maybe rename it to something like
> notes/ in the ebbr-for-discussion repo itself so the usual PR workflow
> is available? Thanks!
Done:
https://github.com/glikely/ebbr-for-discussion/blob/master/soc-boot-behavio…
g.
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.
On Fri, May 4, 2018 at 8:25 PM, Mark Brown <broonie(a)kernel.org> wrote:
> On Wed, May 02, 2018 at 07:49:57PM +0100, Robin Murphy wrote:
>
>> I guess there's also the possibility that a single driver may want multiple
>> behaviours, if e.g. if SoC variants A and B have some identical peripherals
>> but slightly different pinctrl/IOMMU/etc. hardware such that A has workable
>> default behaviour and can be treated as optional, whereas B absolutely must
>> be controlled by the kernel for the consumers to function properly, and they
>> *should* defer forever otherwise. I think that would pretty much demand some
>> sort of explicitly-curated white/blacklist setup at the subsystem or driver
>> level.
>
> Different board variants, and possibly even different bootloaders might
> also be an issue here - a vendor bootloader might do pinmuxing that an
> upstream bootloader doesn't for example. In some cases the pinmuxing
> even depends on the boot method with things only getting configured if
> the bootloader wanted to use them.
I think this is going to be too big of a hammer for pinctrl at least.
My current thought is to define a pinctrl DT property to indicate pins
are configured already which the OS can use to decide if pinctrl is
optional or not. I'd prefer to keep it simple and be a per pin
controller flag even though this is quite possibly a per client or pin
group state (as you say, the bootloader may only configure what it
uses). Making this per pin group could be a lot of nodes and difficult
to really get right without testing. Making it per pin controller
could make drivers fail in less predictable ways if their pins are not
configured.
Rob
(Whoops, boot-architecture wasn't on cc on this thread, forwarding
message there for public archiving. Please add arm.ebbr-discuss to cc
on any replies.)
On Wed, May 02, 2018 at 06:09:15PM -0400, Tom Rini wrote:
> On Wed, May 02, 2018 at 10:48:11PM +0100, Grant Likely wrote:
> > On 02/05/2018 22:24, Tom Rini wrote:
> > >On Wed, May 02, 2018 at 08:40:42PM +0100, Daniel Thompson wrote:
> > >>
> > >>In terms of the restrictions that come from EBBR mandating GPT:
> > >
> > >Can we step back, why is EBBR mandating GPT?
> >
> > I think EBBR should recommend GPT, but allow MBR if the SoC boot masked
> > rom conflicts with GPT.
> >
> > In the early days of GPT there was also a hybrid GPT+MBR scheme that
> > could list the boot partition in the MBR, but still have a full GPT. It
> > isn't pretty, but there is precidence.
>
> How about recommends GPT but allows MBR, no qualifiers.
So, first of all - a level 0 EBBR _must_ permit MBR, since many
SoCs already out there have ROMs that load firmware.
Secondly, I don't know if should be within the scope of EBBR to
mandate anything at all about a partitioning scheme that is not within
the control of the firmware.
It could mandate support in the _firmware_ for GPT partitioning. But
that is already mandated by UEFI (as well as support for MBR and El
Torito).
But I would really like to see some note and explanation of
restrictions placed on operating systems (i.e., the consumers of the
guarantees provided by the document) by such behaviour in the EBBR.
> As you note
> there's a lot of ways to fiddle around and make it work, probably, on
> all of the existing SoCs that do magic offsets. But it's a lot easier
> to just allow MBR (what the SoCs were designed to have to live with) and
> guide line that in this case nothing before the first 2MiB be used by
> the OS. With a few more spec words around all of that so it's nice and
> formal :)
And if there is a corresponding EBSA coming, I would _really_ like to
see some compliance level banning the reservation of LBA1-LBA33 and
(-LBA1)-(-LBA33) for boot ROM use on any general-purpose block
storage. Clearly not level 0, though.
/
Leif
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
On Wed, May 02, 2018 at 05:39:02PM -0400, Tom Rini wrote:
> On Wed, May 02, 2018 at 05:12:03AM +0000, Chang, Abner (HPS SW/FW Technologist) wrote:
>
> > > -----Original Message-----
> > > From: Udit Kumar [mailto:udit.kumar@nxp.com]
> > > Sent: Wednesday, May 02, 2018 12:26 PM
> > > To: Chang, Abner (HPS SW/FW Technologist) <abner.chang(a)hpe.com>;
> > > Alexander Graf <agraf(a)suse.de>; William Mills <wmills(a)ti.com>
> > > Cc: boot-architecture(a)lists.linaro.org; nd(a)arm.com; Rod Dorris
> > > <rod.dorris(a)nxp.com>; arm.ebbr-discuss(a)arm.com
> > > Subject: RE: DT handling, [Ref Linux-Efi]
> > >
> > > > We probably don't need to provide a genetic DT driver in UEFI U-Boot,
> > > > instead, we will have to mention how SoC/platform vendors publish
> > > > DTB/DTBO in EBBR spec.
> > > > For example,
> > > > The EFI_CONFIGURATION_TABLE in EFI System table could be used to
> > > > publish the pointer to DTB and DTBO. Declare two GUIDs in EBBR, one
> > > > for DTB another for DTBO. OS boot loader is responsible to merge
> > > > DTB/DTBO according DTB/DTBO discovered in EFI Configuration Table. To
> > > > read DT from EFI variable into memory, memory map to DT in EEPROM or
> > > > other mechanisms is platform implementation. No matter which approach,
> > > > DT producer has to create configuration table in EFI system table
> > > > follow the data structure defined in EBBR.
> > > > Another way instead of using GUID in configuration table is to publish
> > > > DTB/DTBO in EFI device path, this way is more UEFI oriented IMO.
> > > > However, we have to defined corresponding device path node in UEFI
> > > > spec for DT. Similar to using system configuration table. DT producer
> > > > has to install EFI device path for either DTB or DTBO. Then OS boot
> > > > loaders locate those EFI device paths of DTB and DTBO and merge it.
> > >
> > > We are adding a requirement on OS boot loaders to merge it.
> > > IMO, merging should be done by firmware itself.
> > > In case, we want to host multiple distribution at same time, then this is likely
> > > to go with OS boot loaders
> >
> > That is fine to merge DT by firmware, we still can standardize how
> > UBoot merges DT in EBBR. For example, SoC and other platform UBoot
> > drivers produce their DT or DTO in their own drivers. UBoot provides a
> > centralized EFI DT driver to collect DT/DTO from either EFI system
> > configuration table or EFI device path. Then this centralized EFI DT
> > driver produces the pointer to point to final DT in EFI system
> > configuration table. OS boot loader cab just check EFI system
> > configuration table to retrieve DT, something like this.
>
> I think I need to step in here to clarify something. U-Boot drivers
> don't produce a DT and while it's possible, it's generally[1] not done,
> that U-Boot uses _the_ device tree that we pass along to the next stage
> (we've likely filtered things out for space and added a few specific
> things of our own).
>
> IMHO, what EBBR should cover is saying that firmware may apply overlays
> because we know there's N valid use cases of taking a base and fixing it
> up in both big and small ways. Then firmware will pass along to the
> next stage (EFI application such as GRUB or *BSD loader or a Linux
> Kernel or ...).
Which bits of this discussion target level 0 and which target a later
level 1?
Personally I'm not sure there is enough prior art w.r.t. device tree
overlay for anything much related to overlays to target level 0.
In fact if we take the view that EBBR defines a contract between the
system firmware and the OS then arguably DT update is also out of scope
unless we are defining runtime services by which the OS can update the
DT. Again not something I think is ready for level 0.
To be clear I don't dispute that good system firmware should make DT
update easy, simply that I'm not sure how it fits into EBBR.
Daniel.
# 26 April 2018
## Attendees
* Abner Chang (HPE)
* Palmer Dabbelt (SiFive)
* Andreas Färber (SUSE)
* Alex Graf (SUSE)
* Ryan Harkin (Linaro)
* Rob Herring (Linaro)
* Udit Kumar (NXP)
* Grant Likely (Arm)
* Leif Lindholm (Linaro)
* Bill Mills (TI)
* Tom Rini (Konsulko)
* Michal Simek (Xilinx)
* Daniel Thompson (Linaro)
* Dong Wei (Arm)
## Agenda
* Action item review
* Behaviour without persistent variables
* DTB Update policy/behaviour
* Any other business
## Notes
### Action item review
* Relicense and publish EBBR
* Slipped by one week per week (progress as been made… but wheels
still need to turn)
* Github repo
* Complete but cannot be published until relicensing action
(above) is complete
* Policy for sharing HW between firmware and OS
* NTR, next week
* Handling platforms without persistent variables
* Proposed text shared on mailing list
### Behaviour without persistent variables
* Grant: Role of EBBR. It **interprets** UEFI and it **restricts**
UEFI (by implication to things supportable in u-boot)
* Alex:
* Current code in SUSE depends on no variables presented if
persistent variables are not supported
* would return device error for EBBR level 0 on GetVariable()
* Leif: Need plan for read-only variable implementation
* Daniel/Grant: No flag day. EBBR level 0 OS must be able to run on
EBBR level 1 firmware. Makes above problematic.
* Bill: No get/set, Get but not set, get/set-temporary, get/set-persisent
* Daniel: Let's ban get/set-temporary
* Leif: get/set-temporary exists in the wild (is it OK for such
systems to be non compliant.
* Identified scenarios:
* No get/set
* Get, but no set
* Get & Set, but Set does not persist
* Get & Set fully works
* Use case 1:
* Distro needs to decide how to install itself
* Either using variables (standards compliant) or like removable
media
* Use case 2:
* Use non-persistent variables to alter boot order and allow the
variable to survive, in RAM, through the OS and firmware reset and allow
it to select the next kernel to be booted
* Bill/Daniel: Distros already have a tool that can achieve
similar use-case (grub) and this is a property of the distro not a
property of EBBR
* Grant:
[https://cateee.net/lkddb/web-lkddb/EFI_BOOTLOADER_CONTROL.html](https://cat…
(not full variable support, simply a means to pass a single message
bootloader, good for A/B style updates and temporary diversions of
kernel under dirtect)
* Leif:
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](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._
* Grant: What are the scenarios/use-cases enabled by the statically
defined image support, etc.
* Leif: Is this images exists then I want to run it on boot, update
configuration tables, etc.
* Grant: Need concrete use-cases, could ban these variables from
existing unless user interferes/hacks with the bootloader (e.g. u-boot
has persistent variables… its just that we cannot set them at runtime)
* Grant: Can/should an EFI application be able to set variables
persistently (or temporarily)? (for example configuring network booting
parameters during initial commissioning)
* Summary:
* We follow UEFI spec w.r.t variables
* Boot, OSRecover, etc variables ship undefined
* Fallback to removable media boot in the absence of boot variables
* Didn't catch the last one!
* Leif: Did we get agreement to require that variables be persistent
but only if they are set from boot services?
### Any other business
* Capsule update and other runtime variables
* Udit: Is this optional? Like persistent variables.
* Leif: Yes, in first version we should make this optional for
similar reasons to persistent variables
* Leif: We **want** the runtime services to be supported long
term, so we focus on optionality on a case by case basis rather than
ruling them all out wholesale
* Grant: Runtime services are not optional… we are simply
allowing them not to work (return failed)
* Udit: Also wants get/set long term
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 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.
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 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.
Time: Every Thursday at 16:30-17:30 BST (8:30 PDT, 23:30 CST)
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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.
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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Join by Phone +44 2033215213,, 4664465#
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