https://bugs.kde.org/show_bug.cgi?id=515786
--- Comment #24 from James <[email protected]> --- SUMMARY plasmashell reliably segfaults in ScreenPool::isOutputFake() at every login on NVIDIA Wayland session, causing a 10-15 second black screen before the desktop appears. Reproducible 100% of the time on every login. STEPS TO REPRODUCE 1. Boot system and reach SDDM (Wayland greeter) 2. Log in to a Plasma (Wayland) session 3. Screen shows no signal for 10-15 seconds while plasmashell crashes and is restarted by systemd; the desktop then appears fully formed and works normally afterward OBSERVED RESULT plasmashell segfaults during startup, in ScreenPool::isOutputFake() (screenpool.cpp:125), called from the ShellCorona constructor. The journal shows "requesting unexisting screen available rect -1" and "There are no outputs - creating placeholder screen" immediately before the crash, suggesting plasmashell starts before kwin_wayland's output is ready and crashes on the placeholder screen. systemd restarts it and the session eventually recovers. Two coredumps are typically produced per login. I have also seen a SIGABRT variant where plasmashell aborts in QGuiApplicationPrivate::createEventDispatcher (unable to connect to the Wayland display), consistent with the same startup race. Backtrace (symbolized via debuginfod, SIGSEGV): #5 ScreenPool::isOutputFake(QScreen*) const at plasma-workspace-6.6.5/shell/screenpool.cpp:125 #6 ScreenPool::ScreenPool at plasma-workspace-6.6.5/shell/screenpool.cpp:43 #7 ShellCorona::ShellCorona(QObject*) at plasma-workspace-6.6.5/shell/shellcorona.cpp:109 #8 main at plasma-workspace-6.6.5/shell/main.cpp:117 Full backtrace with locals (bt full / thread apply all bt) attached. EXPECTED RESULT plasmashell waits for outputs to be available (or tolerates their absence) and the session starts without crashing. SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 6.6.5 (plasma-workspace 6.6.5-2, kwin 6.6.5-4) KDE Frameworks Version: (kcrash 6.26.0) Qt Version: [output of pacman -Q qt6-base] Kernel: [output of pacman -Q linux] Graphics: NVIDIA RTX 4090 (nvidia-open [version], DRM modeset enabled, early KMS via initramfs) + AMD Raphael iGPU (no display attached) ADDITIONAL INFORMATION - Monitor: 4K 240Hz over DisplayPort; in-session mode changes and VT switches are fast — only session startup is affected - KWIN_DRM_DEVICES=/dev/dri/card1 is set (pointing at the NVIDIA card) to prevent kwin selecting the output-less iGPU; the crash occurs regardless - SDDM greeter running on Wayland; same behavior with the X11 greeter - Possibly related to bug 515786 (NVIDIA login-time plasmashell crash), though that report shows a Wayland protocol error rather than this ScreenPool segfault - Happy to provide further logs or test patches; crash is reproducible on demand -- You are receiving this mail because: You are watching all bug changes.
