Disk unlock prompt is never displayed. Screen stays black.

[John Doe]

Unfortunately the screen stays black before password prompt shows up.
This happens since I've migrated from 22.04 to 24.04.
Even a fresh install shows the same symptoms.

What helps is to detach the HDMI cable, attach it again and the TV shows the password prompt for luks.

I did not try yet the removal of "splash" in the parameters. As this was indicated by others who faced the same issue.

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: gdm3 46.0-2ubuntu1
ProcVersionSignature: Ubuntu 6.8.0-45.45-generic 6.8.12
Uname: Linux 6.8.0-45-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.1
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Tue Oct 1 08:12:07 2024
InstallationDate: Installed on 2024-09-29 (2 days ago)
InstallationMedia: Ubuntu 24.04.1 LTS "Noble Numbat" - Release amd64 (20240827.1)
ProcEnviron:
 LANG=de_DE.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
SourcePackage: gdm3
UpgradeStatus: No upgrade log present (probably fresh install)

[Daniel van Vugt (vanvugt)]

Thanks for the bug report.

Please run:

  sudo apt install drm-info
  sudo drm_info > drminfo.txt
  lspci -k > lspci.txt

and attach the resulting text files here.

[John Doe (johndoe3467)]

Hello,

thanks for the feedback.

Files requested attached to the INC

[Daniel van Vugt (vanvugt)]

I wonder if there's a race happening (hence intermittent) and sometimes the disk unlock prompt wants to render before the amdgpu driver is available and before the timeout that would switch it to SimpleDRM automatically. Try adding kernel parameter:

  plymouth.use-simpledrm

to /etc/default/grub (like GRUB_CMDLINE_LINUX="plymouth.use-simpledrm") and then run:

  sudo update-grub

and reboot.

[John Doe (johndoe3467)]

Hi Daniel,

it seems it fixed the behavior. I did now several reboots and it works. Thanks a lot!

Q:
Does this have any unwanted side effects?
Can I combine this again with quiet splash without any issue?

Note: This did not happen on 22.04. Machine itself is the same and has not changed.

[Daniel van Vugt (vanvugt)]

Yes Ubuntu 24.04 introduced SimpleDRM, which is used for early boot graphics now. But there are a lot of moving parts and still some bugs.

[Daniel van Vugt (vanvugt)]

> Does this have any unwanted side effects?

The only known side effect is that on some systems, the boot animation and final login screen will disagree about the correct display scale and change size.

> Can I combine this again with quiet splash without any issue?

Yes "quiet splash" should be present and should never be removed.