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

[Alkis Georgopoulos]

> Why not use a 64-bit kernel? Should be a much better option.

Because I'm trying to boot the stock, unmodified
lubuntu-18.04.5-desktop-i386.iso that was released yesterday. It has a
32bit kernel.

> If you manually hacked together an i386 install in UEFI mode, it's up
to you to maintain.

It's just a custom grub.cfg. I believe that using the "loopback" command
to boot a vanilla ubuntu .iso should be within the "normal, supported
use of grub". People using grub should be allowed to ask for support
even though the installer uses grub in a different way. Grub doesn't
exist in the archive only to serve ubiquity.

Anyways, since the problem came from redhat, we should move the
discussion there and the fix will eventually reach Ubuntu, thank you
very much for that information!

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to grub2 in Ubuntu.
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:
  Invalid

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?

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1876737/+subscriptions