Thinkpad T460S won't boot with latest intel-microcode update

[Nicolas Delvaux]

This morning I installed the security update "3.20200609.0ubuntu0.20.04.0" of intel microcode and then, after rebooting, my T460S laptop is stuck with the "loading initial ramdisk" message.
Selecting an older kernel did not help.

What I had to do to recover is boot on a live session, chroot into my system, rollback to intel-microcode version "3.20191115.1ubuntu3" then regenerating initramfs.

Then I was able to reboot normally.

Note that my BIOS/firmware is up-to-date (according to "fwupdmgr update").

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: intel-microcode 3.20191115.1ubuntu3
ProcVersionSignature: Ubuntu 5.4.0-37.41-generic 5.4.41
Uname: Linux 5.4.0-37-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.2
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Wed Jun 10 11:12:04 2020
InstallationDate: Installed on 2017-03-23 (1174 days ago)
InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Release amd64 (20161012.2)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
SourcePackage: intel-microcode
UpgradeStatus: Upgraded to focal on 2020-04-30 (40 days ago)

[Steve Beattie (sbeattie)]

Hi, can you please include the output of

  dmesg | grep microcode

and confirm that the first line contains "sig=0x406e3"?

If so, this is likely a duplicate of bug 1882890.

[Steve Beattie (sbeattie)]

Sorry, second line would contain the 'sig=' entry that identifies the processor family.

[Nicolas Delvaux (malizor)]

Hi Steve,

I confirm:

SRBDS: Vulnerable: No microcode
microcode: sig=0x406e3, pf=0x80, revision=0xd6
microcode: Microcode Update Driver: v2.2.

[Steve Beattie (sbeattie)]

Thanks!

I have packages that revert the problematic microcode back to the version included in the microcode updates from 20191115 available for testing in https://launchpad.net/~sbeattie/+archive/ubuntu/lp1882890/ ; can you confirm that after installing them from that ppa, that you can successfully reboot your system?

[Nicolas Delvaux (malizor)]

I just did that (following what you posted on bug 1882890), and I confirm it now boot as it should.

(I'm going to cross post this on the other bug, in closed this one closed as duplicate)

[Nicolas Delvaux (malizor)]

*in case this one is closed

[Steve Beattie (sbeattie)]

Great, thank you, appreciated. And yes, I'll mark this as a duplicate of the other.