[plasma-login-manager] [Bug 523578] plymouth-quit.service times out and the kwin_wayland process of plasmalogin fails to acquire DRM device /dev/dri/card1 "Device or resource busy"

https://bugs.kde.org/show_bug.cgi?id=523578

--- Comment #3 from [email protected] ---
Unfortunately i cannot get any debuginfod for libQT6Core on cachyOS. 

I tried ` export DEBUGINFOD_URLS="https://debuginfod.cachyos.org
https://debuginfod.archlinux.org"`  but still debuginfod fails:

```
debuginfod-find debuginfo /usr/lib/libQt6Core.so.6
debuginfod-find debuginfo /usr/lib/libQt6Core.so.6.11.1
``` 

============================
According to ClaudeSonnet:

Root cause (confirmed via journal + coredump analysis)

plasma-login-wallpaper starts before the Wayland compositor's socket is
available:

plasma-login-wallpaper[873]: Failed to create wl_display (Connection refused)
plasma-login-wallpaper[873]: Could not load the Qt platform plugin "wayland" in
""
plasma-login-wallpaper[873]: could not connect to display
plasma-login-wallpaper[873]: From 6.5.0, xcb-cursor0 or libxcb-cursor0 is
needed to load the Qt xcb platform plugin.
plasma-login-wallpaper[873]: Could not load the Qt platform plugin "xcb" in ""
plasma-login-wallpaper[873]: This application failed to start because no Qt
platform plugin could be initialized. Reinstalling the application may fix this
problem.

Wayland connection fails ("Connection refused" — nothing listening yet), Qt
falls back to X11/xcb, which also fails (missing libxcb-cursor0), leaving no
usable Qt platform plugin. Qt then calls qFatal(), producing the SIGABRT
coredump:

Program terminated with signal SIGABRT, Aborted.
...
#5  QMessageLogger::fatal(...) (libQt6Core.so.6)
#7  QGuiApplicationPrivate::createEventDispatcher() (libQt6Gui.so.6)
#9  QCoreApplicationPrivate::init() (libQt6Core.so.6)
#11 QGuiApplication::QGuiApplication(int&, char**, int) (libQt6Gui.so.6)

(plasma-login-wallpaper's own frames remain unsymbolicated — neither CachyOS's
nor Arch's debuginfod has debug info indexed for this build/package, so the
exact call site inside the binary itself could not be resolved.)

Two distinct issues, both worth fixing:

Primary: plasma-login-wallpaper is started too early in the boot sequence,
before the Wayland compositor is ready to accept connections — a startup
ordering/race bug.
Secondary: even the X11 fallback path is broken on this system due to a missing
libxcb-cursor0 dependency — should probably be a hard dependency of the
package, or the fallback logic should degrade more gracefully instead of
aborting.

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