coreboot Power9/Power10 support

[tlaurion]

https://doc.coreboot.org/contributing/project_ideas.html#support-power9-power8-in-coreboot

Hardware provided by RaptorEngineering

• RYF board: Talos II

[tlaurion]

Interests to have Open Source Hardware and Compartmentalization for the future of computing:

• Libre RISC-V -> Power based free GPU
• QubesOS PPC64 support

@madscientist159

[tlaurion]

@pietrushnic :)

[miczyg1]

@3mdeb is evaluating the effort of porting the POWER9 Talos II and Talos II Lite to coreboot. The plan should be announced soon.

[tlaurion]

Underway!

[macpijan]

@tlaurion As you know the coreboot effort is progressing (https://github.com/3mdeb/openpower-coreboot-docs/tree/main/releases, https://github.com/3mdeb/coreboot/tree/talos_2_support_payload).

I believe we are at the point where we could start working on heads, so we can start testing faster once the coreboot bits are in place. I can see following tasks:

1. Review kernel patches from skiroot

• Review kernel patches in skiroot: https://git.raptorcs.com/git/talos-op-build/tree/openpower/linux
• Review the tree (https://git.raptorcs.com/git/talos-op-linux/) if it carries
  some addiitonal patches. At a first glance, it looks as like a plain linux
  tree, though.

2. Update Linux

• Use the same version as in: https://git.raptorcs.com/git/talos-op-linux/ for simplicity
• Apply patches from (first task) if necessary. If unsure, better to apply at first.
• Simply add support for the linux we need here (and apply patches if needed):
  https://github.com/osresearch/heads/blob/master/modules/linux ; preferably
  this linux version is only used for the talos II target
• we can test it somehow, but it does not need to build at this point yet (we
  will try to do that in fourth task)

3. Update coreboot - build from 3mdeb's fork for now

• Add the possibility to build coreboot from this branch:
  https://github.com/3mdeb/coreboot/tree/talos_2_support_payload
• As in the Linux case:
  • https://github.com/osresearch/heads/blob/master/modules/coreboot
  • should be a variant, used only by the Talos II board for now
  • dosn’t need to build correctly yet in this task

4. Add config for Talos II board

• configs are here: https://github.com/osresearch/heads/tree/master/config
  • there is one for coreboot and one for Linux
  • the coreboot config: https://github.com/3mdeb/coreboot/blob/talos_2_support_payload/configs/config.raptor-cs-talos-2
  • the Linux config - ideally find out which is the config used in op-build:
    https://git.raptorcs.com/git/talos-op-build/tree/
    we can also flash the original image and dump config from Linux userspace
    (e.g. /proc/config.gz if it exists) ; we know that the in-tree
    powernv_defconfig is the default one for POWER9 and it works ok on our board,
    so we could use that as well probably
  • there might be some additional requirements heads has on the kernel
    configuration which are not present in the original config used in the
    op-build (e.g. drivers for smart cards etc.)

Please let me know if you see anything more. If the plan looks ok, we could split them into issues and track the progress in public here.

[macpijan]

There are two more complex threads as well here.

1. We won't be able to start heads kernel as a coreboot Linux payload as it is currently done for other platforms. At least for now, we only can start skiboot from coreboot. We need it for OPAL. Then, the skiboot can load Linux - in this case it could load heads kernel and initramfs.

2. AFAIK, heads currently build everything in this repo and assembles it into a single ROM file to be flashed in the SPI. In case of the POWER9, we also need to build a single flash image (PNOR). It is, hovewer, much more complex process. Apart from the coreboot and heads stuff, we need a proper layout of this file and some more firmware files (like the OCC firmware which is also briefly mentioned here). The PNOR file and all of the firmware components are built using this repo: https://github.com/open-power/op-build Replicating the PNOR layout creation and building all of the firmware components as part of the heads repo would be quite complex.

Currently, we are reusing the existing build scripts from the op-build repository. We output PNOR file from there and replace Hostboot with coreboot. We propose to do the similar here. So we could build the PNOR file first from the original op-build repository and then replace selected partitions:

• Hostboot with coreboot
• skiroot + petitboot with heads kernel + heads initramfs

There is a tool which allows us to modify the existing PNOR firmware file: https://github.com/3mdeb/openpower-coreboot-docs/blob/main/devnotes/porting.md#ffs-tools

[tlaurion]

@macpijan I can try to do a quick PR draft on which the first points would be addressed as a start.

• modify coreboot module so that a new version points to a specific commit and download and measure the tarball checksums for power.
• modify linux module so that a new version does the same as above, and have the patches available in the patches directory for the same version (git commit) to be applied post decompression prior of building
• create a board configuration which will point to:
  • Put basic power coreboot config in tree
  • Put basic linux config in tree

Would that be helpful as a start? It seems it would ease onboarding to heads ecosystem, while the build will probably fail, of course.

[SergiiDmytruk]

@tlaurion Yes, that would be helpful and speed things up.

[SergiiDmytruk]

I decided to not wait and give it a try and might have addressed basic points already, hope you didn't start yet. My WIP changes are here if you want to take a look and maybe correct obvious mistakes early on. Doesn't build yet (kernel build complains about non-retpoline compiler).

[macpijan]

In regards to Linux config: I believe this one is rather used: https://git.raptorcs.com/git/talos-op-build/tree/openpower/configs/linux

The config dumped from running device: https://github.com/3mdeb/openpower-coreboot-docs/pull/41/files

[tlaurion]

retpoline

@SergiiDmytruk
268fb90#diff-a890ddf36ae7dca110b70df101c97525a4d8265212ebed3f92562d47162af3a2R322

You can remove support inside of the linux config. Everything looks good at first glance.
Not sure if the 5.5 kernel line and patches should be shared across all boards that would depend on it or if the version specified under modules/linux should be power related only?