Display artifacts with 6x Displays
Affected version
gnome-shell 45.3 (currently running repo=copr:copr.fedorainfracloud.org:scorpionit:mutter_nvidia_dynamic_triple_buffering for !3304 (merged), but this bug also exists in the base release) Fedora Silverblue 39.20240129.0
Bug summary
I have 6x 4K (3840x2160) displays spread across Intel i915 iGPU and an nvidia GTX3090. Physically these are in 3 horizontal x 2 vertical (11520x4320) configuration.
Without a monitors.xml; gnome-shell assumes a default display of 6 horizontal x 1 vertical configuration (23040 x 2160). In this configuration the desktops are "squashed" horizontally and do not fill the monitors. The mouse pointer can span the whole space but does not align with the underlying desktop. Monitor 6 has no content, monitor 5 is squashed and only fills 10% of the desktop, desktops 1-4 rendered but are "squashed" using only 50-75% of the available monitor. If I had to take a wild guess I'd say the framebuffer width of 23040 can't be fully allocated and the smaller framebuffer eventually allocated throws some calculations off somewhere (is width capped at 16384 somewhere?). When I can (very awkwardly due to pointer alignment issues) set my display settings to 3x2 = 11520x4320 @ 150% scaling, everything works great.
Steps to reproduce
Connect 6x 4K displays and let gnome try and initialize them.
What happened
What did you expect to happen
Relevant logs, screenshots, screencasts etc.
Output from:
gdbus call -e -d org.gnome.Mutter.DisplayConfig -o /org/gnome/Mutter/DisplayConfig -m org.gnome.Mutter.DisplayConfig.GetCurrentState
gdbus call -e -d org.gnome.Mutter.DisplayConfig -o /org/gnome/Mutter/DisplayConfig -m org.gnome.Mutter.DisplayConfig.GetResources
Attached.