[Bug 1882890] Re: intel-ucode/06-4e-03 from release 20200609 hangs system in early boot

[Paulo J. S. Silva]

Same problem here on Ubuntu 20.04 in a Dell Latitude E7470 with a Core
i5-6300U. The machine hangs on boot. I can not even reboot the machine
using the alt-prtsc-b. It was completely frozen. Only a long press on
the power button would work. My workaround was to boot into recovery
mode (maybe you a need an older kernel for that) and do a

apt --purge remove intel-microcode

The purging process rebuilds initramfs. After that I could reboot again.

Here is the output asked above.

pjssilva at trinity:~$ dmesg | grep microcode
[    0.102417] SRBDS: Vulnerable: No microcode
[    0.578849] microcode: sig=0x406e3, pf=0x80, revision=0xcc
[    0.578971] microcode: Microcode Update Driver: v2.2.

This looks like a serious bug. Maybe pull out the update from the
repositories until a solution is found?

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https://bugs.launchpad.net/bugs/1882890

Title:
  intel-ucode/06-4e-03 from release 20200609 hangs system in early boot

Status in intel-microcode package in Ubuntu:
  Confirmed

Bug description:
  Hi,

  This morning I applied the latest updates on my Ubuntu 16.04 (kernel
  4.15.0-106-generic + intel-microcode 3.20200609.0ubuntu0.16.04.0) and
  rebooted as usual to boot on the new kernel but the system won't boot:
  black screen.

  I tried booting the previous kernel 4.15.0-101 and it seems to be the
  same : in grub I select the 4.15.0-101 kernel, press enter, a message
  "Loading initrd..." is printed but nothing else happens.

  Tried even older kenrel 4.4.0-184-generic : same problem, "Loading
  initrd...", and nothing happens.

  I managed to boot a 4.4.0-142-generic, but bluetooth and wifi are non-
  functionnal.

  I mounted the /boot partition from a USB rescue drive, and it seems that all the initrd images that got updated this morning are not bootable anymore :
  - initrd.img-4.15.0-106-generic
  - initrd.img-4.15.0.101-generic
  - initrd.img-4.4.0-184-generic

  I tried regenerating the images with update-initramfs but it's the
  same : "Loading initrd" message but nothing happens.

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