[regression] cyclic reboot caused by the amd microcode updater

I rolled back the amd64-microcode to the previous version (3.20180524.1~ubuntu0.14.04.1 to 2.20131007.1+really20130710.1) and it resolved the issue, I can now boot to 151, so it is definitely related to amd64-microcode. I am using AMD Phenom(tm) II X4 975 Processor

FYI. I am hit by this problem too. Updated system in Synaptic on 26th which included
Upgrade: amd64-microcode:amd64 (2.20131007.1+really20130710.1, 3.20180524.1~ubuntu0.14.04.1)

Had previously installed (2 weeks ago) linux-image-extra-3.13.0-151-generic:amd64 (3.13.0-151.201)

Now system hangs with black screen. Running in recovery mode the last two lines are
x86: Booting SMP configuration:
.... node #0: CPUs #1

Booting back in 3.13.0-149 works fine.

smpboot: CPU0: AMD Athlon(tm) II X4 600e Processor (fam: 10, model: 05, stepping: 02)
Gigabyte Technology Co., Ltd. GA-MA785GM-US2H/GA-MA785GM-US2H, BIOS F12a 07/08/2010

Hope this helps.

Status changed to 'Confirmed' because the bug affects multiple users.

Could you test the new version of amd64-microcode which has been uploaded to trusty-proposed?

Thanks for the report, sorry for the problems you're experiencing. I have uploaded a revert update for the amd64-microcode package to the ubuntu-security-proposed ppa https://launchpad.net/~ubuntu-security-proposed/+archive/ubuntu/ppa ; it would be appreciated to confirm that upgrading to that version does not cause problems.

Thank you Steve, that has resolved the problem.
Tony.

The solution proposed by Steve in comment #6 works for me too (my processor is AMD Phenom 9500 and I was affected by this bug)

This bug was fixed in the package amd64-microcode - 3.20180524.1~ubuntu0.14.04.2+really20130710.1

---------------
amd64-microcode (3.20180524.1~ubuntu0.14.04.2+really20130710.1) trusty-security; urgency=medium

  * REGRESSION UPDATE: revert to 2.20131007.1+really20130710.1 due to
    3.20180524.1~ubuntu0.14.04.1 causing boot looping for some AMD
    processors (LP: #1779092)

 -- Steve Beattie <email address hidden> Tue, 03 Jul 2018 14:11:11 -0700

I wanted to shed some more light on this issue and our decision making after hearing of at least one person that saw this update and thought that this was a regression in the microcode provided by AMD. While we don't yet know the actual cause of this issue, a regression introduced in the microcode itself is not at the top of our list of suspicions. We haven't heard of any similar reports in Ubuntu 16.04 LTS, Ubuntu 17.10, or Ubuntu 18.04 LTS which all received the same microcode updates.

We suspect that it has something to do with the combination of 3.13 kernel's support for early microcode loading, the packaging for the amd64-microcode package, and/or the initramfs generation when injecting new AMD microcode. We're still investigating the cause and will release additional updates when we've tracked down the solution.

To follow up on Tyler's comment, I have placed amd64-microcode 3.20180524.1~ubuntu0.14.04.3 in the ubuntu-security-proposed ppa (https://launchpad.net/~ubuntu-security-proposed/+archive/ubuntu/ppa/) that keeps the packaging the same as before, but includes the 17h family microcode (along with an update for 16h family as well). It woul dbe great if people with various AMD processors could test this, both to confirm that things successfully boot and that the microcode is loaded (should be reported in dmesg).

Including the output of the 'lscpu' command in any feedback would especially be appreciated.

Thanks!

SB> It woul dbe great if people with various AMD processors could test this

CPU: 'AMD E-300 APU with Radeon(tm) HD Graphics'
dmesg and lscpu logs in attacchment

Thanks

The latest update does not solve it for me.
Ubuntu server 18.04
I have a AMD 2300G processor.

I can start my server if I choose this kernel Linux 4.15.0-24-generic x86_64 but not the latest (linux-image-4.15.0-29-generic).