Arch Linux

CLR123

Member

Registered: 2024-07-28

Posts: 4

Configuring NVIDIA + Wayland + SDDM on a hybrid graphics system.

I can't seem to be able to get my dGPU (NVIDIA) working on Wayland, using SDDM and KDE. I have set the "modeset=1" and "fbdev=1" kernel modules, and no matter what, when logging in with Wayland, it uses Mesa Intel UHD Graphics. The wiki does have docs on setting up NVIDIA + Wayland, as does KDE, but neither docs seem to consider the case of hybrid graphics specifically with Wayland.

I managed to get the dGPU working with X11 by modifying SDDM's "/usr/share/sddm/Xsetup" and Xorg's "/etc/X11/xorg.conf.d/10-nvidia-drm-outputclass.conf", as instructed in the wiki, but obviously it won't apply to Wayland. Is there a way I can get it working? I do not intend on switching GPUs, I'll use only the discrete card.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,104

Re: Configuring NVIDIA + Wayland + SDDM on a hybrid graphics system.

Unless you have a physical option of switching to the dedicated card in your UEFI or you're only using external monitors directly attached to the dGPU you can't run solely on the nvidia GPU.

And doing so just for the premise of using the "more powerful card" will run you into a bunch of performance issues and synchronisation problems when dealing with workloads the integrated card is more than capable of. Because you still need to render a final image via the screen attached internal card. And if the cost of rendering and copying said image over the dedicated card is greater than rendering and displaying the image directly via the iGPU you'll net a loss in performance and power consumption.

Thus the "correct" way to do this is identify applications that actually benefit from the dGPU and then actively using PRIME for these specific usecases.  https://wiki.archlinux.org/title/PRIME# … er_offload

If you still want to do this despite these concerns, export KWIN_DRM_DEVICES at a location before starting plasma/KWin make sure you list both devices colon separated, but the dGPU first: https://invent.kde.org/plasma/kwin/-/wi … rm_devices

CLR123

Member

Registered: 2024-07-28

Posts: 4

Re: Configuring NVIDIA + Wayland + SDDM on a hybrid graphics system.

Right, that makes sense... So even when System Settings in X11 said that it was using Nvidia as the graphics processor, the screen is still actually attached to the iGPU? (My UEFI settings indeed don't have an option of choosing GPU). I experimented running heavier programs with "prime-run", and it does seem to work (Minecraft at least, Steam isn't, will try to fix it).

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,104

Re: Configuring NVIDIA + Wayland + SDDM on a hybrid graphics system.

Don't run steam itself with prime-run, add it to launch options (of native games, things on proton using DXVK and VKD3D will automatically opt for the dedicated GPU by default anyway)