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

[Alkis Georgopoulos]

Thank for you all the feedback guys,

OK, since upstream already replied "won't fix", of course there's no point to report an issue.
As long as i386 installations are still supported, we that need this functionality, can keep using the last working grub.

> Why are you not using -amd64.iso?

One use case is to be able to use the same .iso or live USB or netbooted
installation for many client computers. For example, we have a few
hundred schools here that have both 32bit and 64bit clients; they all
netboot from a 32bit installation so that the teacher doesn't have to
maintain many installations. We can keep using the old grub until 18.04
is EOLed in 2023.

Another use case is to be able to troubleshoot 32bit-only bugs in 64bit
hardware (that in some cases only supports UEFI booting); for example,
Ryzen/amdgpu-based computers currently show black screen with 32bit
installations yet they work fine with 64bit.

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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:
  Won't Fix

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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