Update to fedora 40 renders plasma-desktop and sddm unusable (slow, sluggish, unresponsive)

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Hello,

I just updated my fedora 39 system to fedora 40 (beta). It was a smooth transition expect that the update makes sddm and plasma-desktop hardly usable. This is because mouse and keyboard become very slow, sluggish, unresponsive.

To circumvent the problem i installed xfce, use non graphical login and start xfce with startxfce4 currently. Xfce desktop experience seems not to be effected by the problem.

Some more information about the system:

  • fedora 40 uses plasma 6, e.g. kwrite is version 24.02.1 based on kde framework 6.0.0 and Qt version 6.6.2
  • nvidia driver (550.67) (not using nouveau because I need cuda)
  • no problems like this with f39 before
  • NVIDIA Corporation TU106 [GeForce RTX 2060 Rev. A] (rather old)
  • When I start a kde-plasma application on CLI (e.g. kwrite), I see the following:
    DRM kernel driver 'nvidia-drm' in use. NVK requires nouveau.
MESA: error: ZINK: failed to choose pdev
glx: failed to create drisw screen

Anyone with the same problem? Any suggestions what to do?

Kind regards,

aanno

2

Do you have vulkan-nouveau or something like that installed?
I suspect the nvidia driver and that would be in conflict.

If you are not using nouveau, make sure to remove it, there might be conflicts there too.