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EBBR Notes 2024.02.26

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Vincent Stehlé edited this page Feb 27, 2024 · 1 revision

Attendees

  • Heinrich Schuchardt (Canonical)
  • Andreas Färber (SUSE)
  • Ilias Apalodimas (Linaro)
  • Etienne Carrière (STMicroelectronics)
  • Vincent Stehlé (Arm)

Agenda

  • Pull request #116: Recommend SMCCC >= 1.1
  • Pull request #109: Add an extension for UEFI references (not DTSPEC anymore)

Notes

  • The two pull requests have been reviewed and should be merged after addressing the comments.
  • Discussion on HTTP Boot; as one scenario works for real in U-Boot, further work with the distros would be welcome (solve ramdisk / options handover).

Raw notes

  • Pull request #109: Add an extension for UEFI references (not DTSPEC anymore)
    • Heinrich reviewed.
    • Two comments to address and merge after that.
  • Pull request #116: Recommend SMCCC >= 1.1
    • When will we make that change? (to require PSCI + SMCCC and get rid of spin tables). Does it make sense for a single core? One motivation: system reset.
    • Merge and address spin table in separate changes.
  • EFI HTTP boot
    • Add a recommendation. Merged in U-Boot, tested with openSUSE and Fedora. Largely working. Problem of ramdisk handover. Bootoptions, kernel command line. Do not propagate through shim and GRUB; fix in a generic way.
    • pmem node can be used if distros enable the driver.
      • ramdisk disappears after exit boot services when starting the installer, but the pmem node survives. pmem generic enough? edk2 w/ACPI uses NFIT.
      • Kconfig option to enable: CONFIG_OF_PMEM for Devicetree (CONFIG_ACPI_NFIT for ACPI)
      • Suggest distros add it, so that we can test. Do not standardize?
    • We have some requirements around HTTP Boot in EBBR already:
      • "HTTP Boot | Required if the platform supports network booting. (UEFI § 24.7)"
      • Needs some pruning?
    • There is "13.17.1 EFI_RAM_DISK_PROTOCOL", but probably disappears after exit boot services...
    • How does that work on x86?
      • Action: Ilias to investigate
    • Fedora: inst.stage2= from GRUB on kernel command line.
    • UEFI Shell uses the EFI network stack, but distros not that much, maybe?
      • How different is HTTP vs. TFTP, which was working in the past? Stack for HTTP(S) is bigger. TFTP difficult to deploy massively. Expose simple network protocol, could implement TFTP/UDP/IP in GRUB.
    • Schedule specific EBBR for distros? People in Taiwan, in the US.
      • Ilias to figure out the delta (see above) and then let's schedule an ad-hoc EBBR discussion.

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