I have a laptop with an Intel UHD 630 and NVIDIA GTX 1660Ti with NVIDIA PRIME offloading set up. Plugging in a monitor works fine and I can use it, except if I try to use NVIDIA GBM backend with GBM_BACKEND=nvidia-drm, Hyprland/Sway crashes. I’m on Arch Linux with kernel 6.5.9-zen2-1-zen and NVIDIA driver version 535.113.01, using Hyprland since Sway has flickering issues. Here’s a relevant Hyprland issue which might have some more details: #1878.
Also, my FPS drops down below 30 every few minutes in most games on my external monitor. Didn’t used to have this issue before when I was only using my laptop monitor. Temperatures seem to be staying the same as it used to be with only the laptop monitor so it can’t be thermal throttling, although I do not know of a way to confirm it for sure. Thought it might be some weird issue with PRIME so I tried running external monitor on only NVIDIA card using WLR_DRM_DEVICES=/dev/dri/card1 to pick the NVIDIA card which I got the same results with. Nothing much else I’ve found that I can try, so creating a bug report which hopefully helps fix this.
Update: Without WLR_DRM_DEVICES=/dev/dri/card0 (it changed since I did a full reinstall) Hyprland and Sway both crash when the GBM backend is enabled but currently with sway-git and WLR_DRM_DEVICES=/dev/dri/card0, Sway does not crash. However, Hyprland still crashes with or without the variable if I try to enable the GBM backend. Sway does crash if I am not exclusively using the NVIDIA GPU using WLR_DRM_DEVICES=/dev/dri/card0.
Update 2: Hyprland and Sway no longer crashes with GBM_BACKEND=nvidia-drm as of NVIDIA driver version 545.29.02 with or without WLR_DRM_DEVICES=/dev/dri/card0. However, the FPS drops remain.
Update 3: Tried my best to confirm that my CPU was not thermal throttling by disabling thermald daemon and auto-cpufreq, then trying throttled to make sure my CPU is not being throttled early. Still having the FPS drops on both Hyprland and Sway, regardless of whether WLR_DRM_DEVICES=/dev/dri/card0 variable is present or not.
Nevermind, I’m dumb. CPU was indeed thermal throttling, had zero FPS drops when I tried disabling BD PROCHOT. It was kinda weird that it only happened when external monitor was plugged in and since it didn’t happen on Windows I went ahead and assumed it wasn’t related to throttling but now it’s all fine.