[Bug 1911959] Re: Fresh Ubuntu 20.04 won't boot after intel-microcode update on ThinkPad T460s

[Henrique de Moraes Holschuh]

For the record: systems with firmware outdated enough to actually hit
this microcode update issue *most likely* have several other critical
security issues in their Intel platform, not just in the processor.

The outdated firmware not only blocks you from updating the processor
microcode (thus several processor issues remain), but also very likely
has vulnerabilities in other platform components such as the Intel
Management Engine.

It is your decision to keep your system running like that, but please
ensure you actually understand the risks you are taking: review the
missing firmware update changelogs/advisories/release notes in your
system vendor's website to understand which fixes you are missing, and
also check the running processor microcode version to understand which
processor microcode fixes you are missing.

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https://bugs.launchpad.net/bugs/1911959

Title:
  Fresh Ubuntu 20.04 won't boot after intel-microcode update on ThinkPad
  T460s

Status in intel-microcode package in Ubuntu:
  Confirmed

Bug description:
  Installed Ubuntu 20.04 from USB disk using the first Ubuntu 20.04
  installation image released end of April. The system installs and
  boots fine. Then, I run a system update via `apt update && apt
  upgrade` with updates to Ubuntu 20.04.1. intel-microcode is updated on
  this occasion to version 3.20201110.0ubuntu0.20.04.2. Update
  installation succeeds but subsequent reboots most of the time fail. I
  can access GRUB but a normal boot of any of the installed kernels
  results in either a black screen or a screen with a cursor blinking ad
  infinitum. Booting in recovery mode via GRUB and then "resume" works,
  but external display is not detected in this case. Sometimes however
  (maybe 1/5 of the time), making a reboot from this state works.

  When I uninstall intel-microcode via `apt purge intel-microcode` the
  problems disappear. I can boot the system without any problem.

  I had occasional boot problems already since several months, but they
  could be resolved by just rebooting (pressing the power key for a long
  time). After the latest update, this wouldn't work anymore, so in the
  end I tried out re-installing Ubuntu which resulted in the problems
  described above.

  I'm using a Lenovo ThinkPad T460s with system firmware version
  N1CET37W (1.05) which is quite old.

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