Bug 514641

Summary: PC sometimes boots to black screen (KWin is not running)
Product: [Plasma] kwin Reporter: Oliver Schramm <oliver.schramm97>
Component: platform-drmAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED UPSTREAM    
Severity: grave CC: akselmo, kdedev, nate, xaver.hugl
Priority: VHI    
Version First Reported In: 6.5.4   
Target Milestone: ---   
Platform: Fedora RPMs   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Journald log

Description Oliver Schramm 2026-01-15 11:10:27 UTC
Created attachment 188546 [details]
Journald log

Sometimes, when I boot my laptop (cold boot), all I can see is a black screen after plymouth disappears. It is responsive, I can go to tty2, tty3, but tty1 is just empty.
I can even login to tty2 and try to start plasma from there, but there will be small weirdnesses like no app.slice in systemd.

The sddm-helper-start-wayland prints these messages: (split into multiple lines by me)

No backend specified, automatically choosing drm
Accepting client connections on sockets: QList(\"wayland-0\")
kwin_core: Failed to open drm node: \"/dev/dri/card1\"
kwin_wayland_drm: No suitable DRM devices have been found
QThreadStorage: entry 6 destroyed before end of thread 0x5591069f70a0
QThreadStorage: entry 1 destroyed before end of thread 0x5591069f70a0
QThreadStorage: entry 0 destroyed before end of thread 0x5591069f70a0

Because of that output, I presume it is something racy. Whatever it is, that open() somehow syscall fails.

STEPS TO REPRODUCE
1. Cold boot

I’m sorry, it is very inconsistent and hard to reproduce even for me.

OBSERVED RESULT
Black screen.

EXPECTED RESULT
Login screen (sddm in my case)

SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 43
KDE Plasma Version: 6.5.4
KDE Frameworks Version: 6.22.0
Qt Version: 6.10.1
Kernel Version: 6.17.12-300.fc43.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 12 × AMD Ryzen 5 7535HS with Radeon Graphics
Memory: 16 GiB of RAM (12.7 GiB usable)
Graphics Processor: AMD Radeon 660M

ADDITIONAL INFORMATION
I’ve attached the relevant log (basically the complete life of the sddm user — it’s pretty short).
Comment 1 Akseli Lahtinen 2026-01-15 15:20:26 UTC
This sounds very similar to me as 511118 so marking as duplicate. (I might be wrong however)

*** This bug has been marked as a duplicate of bug 511118 ***
Comment 2 Oliver Schramm 2026-01-17 02:48:48 UTC
Might be, I am not sure of the internals of KWin. The workaround for that other bug is much better however than for this one, because in my case, KWin isn't running anymore and I can only reboot or start it manually from tty.
Comment 3 Akseli Lahtinen 2026-01-19 08:41:33 UTC
Hm, I'll reopen this then and show this to KWin folk, they will know better. Thanks for clarifying!
Comment 4 Zamundaaa 2026-01-19 13:37:38 UTC
I'm pretty sure this is https://github.com/sddm/sddm/issues/1917

We already have some retry logic in KWin, maybe we can extend it more.
Comment 5 Bug Janitor Service 2026-01-19 14:10:49 UTC
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/8673
Comment 6 Oliver Schramm 2026-01-21 00:06:33 UTC
Btw, it's not easy to reproduce that way, but it's kinda consistent, when you take the "cold boot" literally. I encountered this issue most often, when I was outside with my laptop in my backpack while it was about -4°C (or colder). When I then turned it on too fast after going inside again, this happens.
I assume now that the graphics aren't initialized fast enough and KWin fails. It is interesting however, that plymouth and everything up to it works.
Comment 7 Zamundaaa 2026-01-21 16:06:27 UTC
Okay, so apparently SDDM and PLM both are missing a workaround that should help with this. At some point we'll be able to implement a full fix (instead of just a workaround) in KWin, until then, the workaround in the display manager will have to suffice.