EBBR Notes 2025.01.15 - ARM-software/ebbr GitHub Wiki

Attendees

  • Ilias Apalodimas (Linaro)
  • Jon Humphreys (TI)
  • Etienne Carrière (STMicroelectronics)
  • Heinrich Schuchardt (Canonical)
  • Ricardo Salveti (Foundries.io/Qualcomm)
  • Vincent Stehlé (Arm)
  • Joakim Bech (Linaro)

Agenda

  • Pull request #137: Require FMP and "on disk" OsIndicationsSupported bits when supported

Notes

  • Pull request #137 was discussed; feedback that changes around the format language are not a definitive clarification and that adding requirements on the OsIndicationsSupported bits to set could be seen as duplicating the UEFI specification. This needs to be reworked.
  • Heinrich shared his experience with UKI-fied kernels, which lead to a discussion rich in technical details.

Raw notes

  • Pull request #137: Require FMP and "on disk" OsIndicationsSupported bits when supported
    • Default in U-Boot for OsIndications is "yes" when SetVariable() at runtime is supported
    • Ilias: we are implicitly requiring the OsIndicationsSupported bits already
    • -> Rework into footnote or similar
    • Existing wording around FMP capsules not fully precise
      • Proposal is not fully accurate either
        • Notion of scatterlist not captured for example
      • -> Keep existing wording, define FMP in acronyms if really needed
  • Heinrich: UKI-fied kernels
    • Issue on MACCHIATObin with upstream Devicetree, will not boot
    • What is the experience with that?
      • Was Jon's feedback that relying on a "good" Devicetree in the firmware was not his experience.
      • Ricardo: forces vendor to provide up-to-date Devicetree, which at least boots. But we know that we also need to be able to boot with OS-provided Devicetree.
    • UKI allows multiple Devicetrees bundled with the kernel, picks the right Devicetree at runtime, calls U-Boot fixup protocol.
    • EDK2 from 5 years ago, Devicetree good enough.
    • U-Boot copying Linux's Devicetree each cycle.
    • UKI allows to sign Devicetree and initrd, too.
    • UKI allows to pick a Devicetree even on ACPI without a Devicetree (e.g. Qcom devices).
    • UKI does install its Devicetree as UEFI configuration table.
    • Ricardo: other frameworks such as systemd do that, too.
    • Linux Devicetree for Macchiatobin has already changed in the past in a non-backward-compatible way.

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