Multi-GPU

General

If your host machine uses multiple GPUs, you may want to primarily use one GPU for rendering all the elements for Hyprland including windows, animations, and another for hardware acceleration for certain applications, etc.

This setup is very common in the likes of gaming laptops, GPU-passthrough (without VFIO) capable hosts, and if you have multiple GPUs in general.

Detecting GPUs

For this case, the writer is taking the example of their laptop.

Upon running lspci | grep -E 'VGA|3D', One can list all the video devices available.

01:00.0 VGA compatible controller: NVIDIA Corporation TU117M [GeForce GTX 1650 Mobile / Max-Q] (rev a1)
06:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cezanne [Radeon Vega Series / Radeon Vega Mobile Series] (rev c6)

Here it is clear that 2 GPUs are available, the dedicated NVIDIA GTX 1650 Mobile / Max-Q and the integrated AMD Cezanne Radeon Vega Series GPU.

Now, run ls -l /dev/dri/by-path

 total 0
lrwxrwxrwx 1 root root  8 Jul 14 15:45 pci-0000:01:00.0-card -> ../card0
lrwxrwxrwx 1 root root 13 Jul 14 15:45 pci-0000:01:00.0-render -> ../renderD128
lrwxrwxrwx 1 root root  8 Jul 14 15:45 pci-0000:06:00.0-card -> ../card1
lrwxrwxrwx 1 root root 13 Jul 14 15:45 pci-0000:06:00.0-render -> ../renderD129

So from the above outputs, we can see that the path for the AMD card is pci-0000:06:00.0-card, due to the matching 06:00.0 from the first command. Do not use the card1 symlink indicated here. It is dynamically assigned at boot and is subject to frequent change, making it unsuitable as a marker for GPU selection.

Telling Hyprland which GPU to use

After determining which “card” belongs to which GPU, we now have to tell Hyprland the GPU we want to use primarily. This is done by setting the WLR_DRM_DEVICES environment variable.

ℹ️

It is generally a good idea for laptops to use the integrated GPU as the primary renderer as this preserves battery life and is practically indistinguishable from using the dedicated GPU on modern systems in most cases. Hyprland can be run on integrated GPUs just fine. The same principle applies for desktop setups with a lower and higher power rating GPUs respectively.

If you wish to use the integrated GPU to run Hyprland, no further action is required. wlroots will set WLR_DRM_DEVICES to the integrated GPU by default.

If instead you would like to use another GPU, you must first create a symlink to the card from the previous section.

ln -sf /dev/dri/pci-0000:06:00.0-card ~/.config/hypr/card

It is not possible to directly use the /dev/dri/pci-0000:06:00.0-card path, as wlroots interprets the colon symbols in the path as separators. Escaping characters will not rectify this.

Afterwards, you must set the WLR_DRM_DEVICES environment variable in hyprland.conf to this linked card.

env = WLR_DRM_DEVICES,~/.config/hypr/card

If you want to set a sequence of fallback cards, symlink another card and set the var as a colon separated list in order of priority.

env = WLR_DRM_DEVICES,~/.config/hypr/card:~/.config/hypr/otherCard

Here, we tell Hyprland to set priorities. If card isn’t available for whatever reason, use otherCard. So if the AMD GPU isn’t available, use NVIDIA.

You should now be able to use an integrated GPU for lighter GPU loads, including Hyprland, or default to your dGPU if you prefer.

Environment variables Uncommon tips & tricks