[Bug 1876737] Re: GRUB refuses to boot a 32-bit kernel when in EFI mode

[Alkis Georgopoulos]

For those looking for the last good binaries, some notes.

Signed (support secure boot), need extraction from the .deb:
Good: https://launchpad.net/ubuntu/+source/grub2-signed/1.136/+build/18767810
Bad: https://launchpad.net/ubuntu/+source/grub2-signed/1.137/+build/18827799

Unsigned, but directly downloadable with plain wget:
Good: http://archive.ubuntu.com/ubuntu/dists/eoan/main/uefi/grub2-amd64/current/
Bad: http://archive.ubuntu.com/ubuntu/dists/eoan-updates/main/uefi/grub2-amd64/current/

Grub publishing history:
https://launchpad.net/ubuntu/+source/grub2-signed/+publishinghistory
Everything later than focal 1.137 and eoan 1.128.2 are broken.

Main grub launchpad page:
https://launchpad.net/ubuntu/+source/grub2-signed

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https://bugs.launchpad.net/bugs/1876737

Title:
  GRUB refuses to boot a 32-bit kernel when in EFI mode

Status in grub2 package in Ubuntu:
  Triaged

Bug description:
  Also reported at https://savannah.gnu.org/bugs/index.php?58300, but
  doesn't occur in Debian's v2.04 from Bulleye, and only occurred in the
  last few months, so it might be an Ubuntu bug.

  This is grub version 2.02-2ubuntu8.15 as reported by "apt show grub-
  efi"

  GRUB2 fails to boot a 32-bit kernel when started in EFI mode (64-bit
  EFI) on a 64-bit x86 CPU, and gives the message:

  "error: kernel doesn't support 64-bit CPUs"

  However, when a bios grub image made by the same version of grub is
  used, with the same kernel, on the same CPU, everything is normal and
  the kernel boots as expected.

  Hence, I know this kernel will boot on a 64-bit CPU, and with a
  previous version of GRUB 2 (unfortunately I don't know which version),
  it also booted fine in 64-bit mode using GRUB-EFI.

  Running with debug=all doesn't seem to provide any extra useful
  information, as far as I can tell - it just lists sectors being read
  and then freed.

  Any ideas as to what's going on?

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