Hi Jose,
On Tue, 3 May 2022 at 02:26, Jose Marinho Jose.Marinho@arm.com wrote:
Hi Simon,
Thank you for reviewing the draft proposal!
Would you be able to share your review comments on the PDF? Currently the document is not in a markup form and is yet to be hosted in a repository. That's the intent for the long term.
Yes it looks like I can do that, so will share with you when done.
Regards, Simon
Cheers, Jose
-----Original Message----- From: Simon Glass sjg@chromium.org Sent: 03 May 2022 08:59 To: Jose Marinho Jose.Marinho@arm.com Cc: u-boot@lists.denx.de; Heinrich Schuchardt xypron.glpk@gmx.de; Ilias Apalodimas ilias.apalodimas@linaro.org; Tom Rini trini@konsulko.com; Samer El-Haj-Mahmoud Samer.El-Haj-Mahmoud@arm.com; Manish Pandey2 Manish.Pandey2@arm.com; nd nd@arm.com Subject: Re: [RFC] Data structure for information handoff between firmware boot stages
Hi Jose,
On Thu, 7 Apr 2022 at 13:23, Jose Marinho Jose.Marinho@arm.com wrote:
Hi All,
The topic of information handoff between TF-A’s BL31 and BL33 (e.g. U-boot
proper, EDK2) was discussed last year in the TF-A and U-boot mailing lists [1], [2].
Examples of information to be handed off between firmware stages are the
TPM log, HOB nodes, etc.
Having a standard data structure which is usable/supported by every
community contributes to code reuse and leads to simpler codebase maintenance.
Some already existing data structures, such as the UEFI HOB list [3], and the
Bloblist from U-boot, were proposed to be employed for the handoffs.
There are pros and cons with both HOBs and Bloblist. The discussion settled with a consensus that a data structure ought to be
defined which encapsulates the best traits of HOBs and Bloblist.
Properties that the data structure should have:
node types identified by an integer,
easily relocatable,
straightforward to append new nodes,
easy to read and append to from resource constrained environments.
The data structure should be suitable to pass information between different
firmware stages, such as:
U-boot SPL -> BL31 -> U-boot BL1 -> BL2 -> BL31 -> U-boot
As requested in the ML, an initial proposal was drafted [4]. The document [4] is an initial proposal (at an alpha stage). The document [4] is being circulated for the purpose of gathering initial
feedback.
This proposal is closely aligned with an ongoing effort in the u-boot mailing
list [5].
The proposal defines 1) a set of standard nodes and 2) the registers used at
the handoff boundary.
Standard nodes:
- fdt node: HW description fdt,
- HOB node,
- ACPI table node: the main use-case for this node is to carry the TPM log.
The document [4] accommodates an OEM range, which enables IMPDEF
nodes to be caried in the handoff list.
By definition, the nodes in the OEM range are not standard and can be
defined per-platform.
Note: the document [4] encapsulates the standard node definition as that is
the simplest approach for feedback gathering.
Once there is sufficient consensus around the proposal, the standard node
definitions should be moved to a project independent repository. The repository location is TBD.
The list of standard nodes is expected to grow with community contribution.
Thank you for the document. Is there a way to comment on it or should I just send you my hand-written markup?
Regards, Simon
Kind Regards, Jose
[1] https://lists.trustedfirmware.org/archives/list/tf-a@lists.trustedfirm ware.org/message/LUIUOVGUMVWID5RUMTYA463KGIU2EHIU/
[2] https://lore.kernel.org/u-boot/CAODwPW_FwFN1E84cV1+nC1aiahiwOL-
TV=mP_6
o8h0y9+pCNvg@mail.gmail.com/
[3] https://uefi.org/sites/default/files/resources/PI_Spec_1_6.pdf
[4] https://developer.arm.com/documentation/den0135/a [5] https://lore.kernel.org/u-boot/20220113022625.413990-1-sjg@chromium.or g/