[Bug 1831789] Autopkgtest regression report (grub2/2.04-1ubuntu26.3)

[Ubuntu SRU Bot]

All autopkgtests for the newly accepted grub2 (2.04-1ubuntu26.3) for focal have finished running.
The following regressions have been reported in tests triggered by the package:

ubuntu-image/1.9+20.04ubuntu1 (arm64)
grubzfs-testsuite/0.4.10 (amd64)


Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-
migration/focal/update_excuses.html#grub2

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

-- 
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/1831789

Title:
  Add "dis_ucode_ldr" to linux boot options for Recovery Mode

Status in grub2 package in Ubuntu:
  Fix Released
Status in grub2 source package in Xenial:
  New
Status in grub2 source package in Bionic:
  New
Status in grub2 source package in Focal:
  Fix Committed
Status in grub2 source package in Groovy:
  Fix Released

Bug description:
  [Impact]
  Due to some recent problems with a microcode update which broke booting of some laptops I suggest adding "dis_ucode_ldr" to recovery mode boot options to allow booting after a bad microcode update.

  See the following topics that describe the problems:
   - https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1829620
   - https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/1

  When such problems occur it's very hard to see that the microcode
  loading is the issue, the booting just hangs at the purple screen,
  even removing "quiet splash" or using the recovery option will not
  show the error.

  We'll need to double check that dis_ucode_ldr works as expected across all architectures.
  According to the kernel docs (Documentation/admin-guide/kernel-parameters.txt), dis_ucode_ldr is x86 only, so my guess is that it will be ignored for other architectures. According to the kernel code  (arch/x86/kernel/cpu/microcode/core.c), dis_ucode_ldr works for both AMD and Intel.
  I have some time tomorrow on test this on a ARM device.

  This was also discussed Ubuntu Developer mailing list where it was
  suggested to post this here, see: https://lists.ubuntu.com/archives
  /ubuntu-devel/2019-June/040725.html

  [Test case]
  Check that dis_ucode_ldr is present on Linux entries

  [Regression potential]
  If you actually require microcode updates to get into userspace, your recovery option won't work anymore. Does this happen? Seems unlikely.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1831789/+subscriptions