Update: the upstream pull request (https://github.com/dracut-ng/dracut/pull/2799) has been closed after review. Hans de Goede (plymouth upstream maintainer and author of the flicker-free boot work) explained that the change in dracut was the wrong place for this: https://github.com/dracut-ng/dracut/pull/2799#issuecomment-6560962360
Summary of his points: - Without UseSimpledrm=1, plymouth ignores the simpledrm framebuffer and waits for the real KMS driver before drawing, exactly to avoid the transition from the firmware framebuffer to the real driver's one, which is the visible flicker. - UseSimpledrm=1 disables that wait. Including the KMS driver in the initrd while keeping UseSimpledrm=1 only changes the timing of a race between plymouth and the driver. - With UseSimpledrm unset, dracut's plymouth module pulls in the drm module, which includes the KMS drivers for the GPUs present. - Benjamin Drung added in the same pull request that the simpledrm module is meant to include only simpledrm, and that the drm module should be used to avoid the flicker. So the flicker on Intel machines is a direct consequence of Ubuntu shipping UseSimpledrm=1 in /usr/share/plymouth/plymouthd.defaults, together with dracut only pulling in simpledrm in that case. As far as I can tell, dracut started pulling in only simpledrm because of LP: #2105377, where plymouth gave up on graphics when simpledrm disappeared as nvidia-drm loaded. That was also fixed on the plymouth side under the same bug. Could the UseSimpledrm=1 default be reconsidered now? If the concern is the initrd size with all GPU drivers and their firmware in a generic initrd, a middle ground would be to drop UseSimpledrm=1 and keep large out-of-tree drivers such as nvidia out of the initrd, as already discussed in the split-out enhancement from LP: #2105377. On my machine (Intel Raptor Lake-P + NVIDIA), the boot is flicker-free with i915 added to the initrd, as described in the bug description. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. 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 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/dracut/+bug/2172151/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
