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)
Join by Phone +44 2033215213,, 4664465#
---
Join online meeting
https://meet.lync.com/armh/grant.likely/YBY93TIK
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Join by Phone +44 2033215213,, 4664465#
Find a local number
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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.
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.
*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.
>
