[Bug 1979123] Re: intel-microcode update disables AVX-512 on Alder Lake

[Alex Murray]

As I said above, you can disable loading of microcode in Ubuntu via the
dis_ucode_ldr kernel command-line parameter by adding this to
GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub and then running update-
grub - but then you won't get the other benefits of the updated
microcode (vulnerability fixes etc).

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Title:
  intel-microcode update disables AVX-512 on Alder Lake

Status in intel-microcode package in Ubuntu:
  New

Bug description:
  Updating intel-microcode to 3.20220510.0ubuntu0.22.04.1 results in
  AVX-512 inaccessible on Alder Lake CPU, even if the BIOS supports it
  and it is enabled in the BIOS. The problematic firmware is
  /lib/firmware/intel-ucode/06-97-02.

  Last known working version of intel-microcode is 3.20210608.2ubuntu1.
  That package version does not contain the microcode (presumably, the
  version loaded by the BIOS is used).

  Please, provide a way to disable this microcode update or blacklist
  its loading on boot.

  ProblemType: Bug
  DistroRelease: Ubuntu 22.04
  Package: intel-microcode 3.20220510.0ubuntu0.22.04.1
  ProcVersionSignature: Ubuntu 5.15.0-39.42-lowlatency 5.15.35
  Uname: Linux 5.15.0-39-lowlatency x86_64
  NonfreeKernelModules: nvidia_modeset nvidia
  ApportVersion: 2.20.11-0ubuntu82.1
  Architecture: amd64
  CasperMD5CheckResult: unknown
  CurrentDesktop: KDE
  Date: Sun Jun 19 02:24:19 2022
  InstallationDate: Installed on 2015-05-01 (2605 days ago)
  InstallationMedia: Kubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
  SourcePackage: intel-microcode
  UpgradeStatus: Upgraded to jammy on 2022-05-14 (35 days ago)

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