[Bug 1815152] [NEW] kernel hangs on boot after "fb: switching to inteldrmfb from VESA VGA"

[Greg Ward]

Public bug reported:

A few days ago, I let update-manager upgrade my kernel from 4.18.0-13 to
4.18.0-14. Since then, my system is unable to boot. It freezes after
printing

  fb: switching to inteldrmfb from VESA VGA

but before it gets around to asking me the passphrase for my encrypted
main partition. (At first I thought it was a problem with cryptsetup
because it never got to that prompt, but now I'm pretty sure it's
something to do with changing video mode.)

However, if I use the grub menu to select the older 4.18.0-13, the
system boots just fine. It looks very much like a bug introduced between
4.18.0-13 and 4.18.0-14.

Additionally, if I boot 4.18.0-14 in maintenance mode, the kernel
modesetting does not happen, and the system boots just fine. (Except for
the 1980s-style low-res video, that is.) This seems like good evidence
that it's a problem with setting the video mode.

I'll test with some mainline builds, but I want to get this bug report
opened before I start rebooting.

** Affects: plymouth (Ubuntu)
     Importance: Undecided
         Status: New

** Attachment added: "boot sequence hung at video mode change"
   https://bugs.launchpad.net/bugs/1815152/+attachment/5236891/+files/hung-kernel.jpg

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https://bugs.launchpad.net/bugs/1815152

Title:
  kernel hangs on boot after "fb: switching to inteldrmfb from VESA VGA"

Status in plymouth package in Ubuntu:
  New

Bug description:
  A few days ago, I let update-manager upgrade my kernel from 4.18.0-13
  to 4.18.0-14. Since then, my system is unable to boot. It freezes
  after printing

    fb: switching to inteldrmfb from VESA VGA

  but before it gets around to asking me the passphrase for my encrypted
  main partition. (At first I thought it was a problem with cryptsetup
  because it never got to that prompt, but now I'm pretty sure it's
  something to do with changing video mode.)

  However, if I use the grub menu to select the older 4.18.0-13, the
  system boots just fine. It looks very much like a bug introduced
  between 4.18.0-13 and 4.18.0-14.

  Additionally, if I boot 4.18.0-14 in maintenance mode, the kernel
  modesetting does not happen, and the system boots just fine. (Except
  for the 1980s-style low-res video, that is.) This seems like good
  evidence that it's a problem with setting the video mode.

  I'll test with some mainline builds, but I want to get this bug report
  opened before I start rebooting.

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