Public bug reported:
Since dracut 106-2ubuntu5 ("plymouth: Only pull in the SimpleDRM driver
by default", LP: #2105377), the 45plymouth module depends only on
45simpledrm, because plymouthd.defaults ships UseSimpledrm=1. As Ubuntu
builds a generic initrd (hostonly=no), no KMS driver ends up in the
initrd unless something else pulls in 45drm.
On Intel laptops this means i915 is loaded from the root filesystem a
few seconds after Plymouth has already started on simpledrm. When i915
takes over the panel, the screen goes black and Plymouth redraws. On
this machine the screen flickered about three times before the GDM
greeter appeared. The same machine boots without any flicker on Windows.
Hardware and versions:
- MSI Prestige 16 Studio A13VE (MS-1594), BIOS E1594IMS.115
- Intel Raptor Lake-P Iris Xe (i915, drives the internal eDP panel) + NVIDIA
RTX 4050 Laptop (nvidia 580.178.04 open kernel module, PRIME on-demand)
- Ubuntu 26.10, kernel 7.3.0-9-generic
- dracut 112-7, plymouth 24.004.60+git20250831.4a3c171d-0ubuntu10
- GNOME 51 on Wayland
Boot timeline before the workaround (journalctl -o short-monotonic):
[0.99] simpledrm initialized
[1.21] plymouth-start.service starts (on simpledrm)
[2.22] switch root
[4.45] i915 probes and takes over the panel -> visible flicker
[4.51] nvidia-drm loads
[9.60] gnome-shell (GDM) adds /dev/dri/card1 (i915)
Workaround:
echo 'add_drivers+=" i915 "' | sudo tee /etc/dracut.conf.d/20-i915-early.conf
sudo update-initramfs -u
Boot timeline after the workaround:
[1.00] simpledrm initialized
[1.24] plymouth-start.service starts
[1.78] i915 probes (still inside the initrd)
[7.44] nvidia-drm loads (from the root filesystem, as before)
Result: no flicker at all from the firmware logo to the GDM greeter. The initrd
grew from 38.5 MB to 44.5 MB (i915 plus its DMC/GuC/HuC firmware).
Proposal:
The race described in LP: #2105377 (plymouth giving up when simpledrm
disappears as nvidia-drm loads) was also fixed on the plymouth side under the
same bug. With that fix in place, would it be acceptable to pull i915 and xe
back into the generic initrd by default, while still keeping the NVIDIA modules
(and other large drivers) out? Intel graphics is by far the most common laptop
GPU, and both Intel-only and Intel+NVIDIA hybrid machines would get a
flicker-free boot again.
If including them unconditionally is too costly, an alternative would be
to include the KMS driver of the GPU that drives the internal panel only
when building in hostonly mode, or to document the add_drivers
workaround in the release notes.
I am happy to test any proposed package.
ProblemType: Bug
DistroRelease: Ubuntu 26.10
Package: dracut 112-7
ProcVersionSignature: Ubuntu 7.3.0-9.9-generic 7.3.0-rc6
Uname: Linux 7.3.0-9-generic x86_64
ApportVersion: 2.36.0-0ubuntu1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sun Oct 25 07:36:58 2026
DracutModulesPackages:
dracut-core 112-7
kdump-tools 1:1.10.7ubuntu5
InstallationDate: Installed on 2026-10-16 (9 days ago)
InstallationMedia: Ubuntu 26.10 "Stonking Stingray" - Official amd64 (20261013)
PackageArchitecture: all
SourcePackage: dracut
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: dracut (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug stonking wayland-session
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https://bugs.launchpad.net/bugs/2172151
Title:
Intel KMS driver (i915/xe) no longer in the initrd since LP: #2105377,
causing visible flicker during boot
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