https://bugs.kde.org/show_bug.cgi?id=477242
Bug ID: 477242
Summary: Kwin duplicates Displays when VM is using Intel GVT-g
Classification: Plasma
Product: kwin
Version: master
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: platform-drm
Assignee: kwin-bugs-n...@kde.org
Reporter: uri...@posteo.de
Target Milestone: ---
SUMMARY
GVTg can be used on some Intel CPUs to provide vGPUs for virtual machines.
Whenever a virtual machine is using a vGPU, the intel driver i915 triggers an
"add" uevent for "/dev/dri/card0" (the integrated intel gpu).
Every single time such an uevent happens, kwin on KF6 adds another duplicate
display.
On current KF5 (5.27.9), the behaviour is different: It causes kwin to freeze
with the warnings:
Nov 19 14:38:35 fedora.gatas kwin_wayland[21784]: kwin_core: Failed to open
/dev/dri/card0 device (Device already taken)
Nov 19 14:38:35 fedora.gatas kwin_wayland[21784]: kwin_wayland_drm: failed to
open drm device at "/dev/dri/card0"
STEPS TO REPRODUCE
1. buy Intel 5th to 10th gen CPU
2. use Plasma 6 via kdesrc-build
3. setup a virtual machine using GVTg
https://wiki.archlinux.org/title/Intel_GVT-g (what form of output you choose
doesn't matter)
4. start VM (again doesn't matter how, if it's "virsh start DomainName" and you
never look at it, it also happens)
OBSERVED RESULT
Flashing and scale change and new monitors keep getting added in the display
settings causing worse and worse performance.
EXPECTED RESULT
Not having a dozen duplicate displays.
SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 39
KDE Plasma Version: 5.81.0
KDE Frameworks Version: 5.245.0
Qt Version: 6.6.0
Kernel Version: 6.5.11-300.fc39.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i7-7700HQ CPU @ 2.80GHz
Memory: 15.5 GiB of RAM
Graphics Processor: Mesa Intel® HD Graphics 630
ADDITIONAL INFORMATION
This is not an issue when using xorg or when using an older kwin_wayland KF5.
But i do not remember the last working version. I just have it in my memory
that i used wayland a few months ago in Fedora 38 and the same VM setup did
work.
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