Vulkan Device Chooser Layer

This is a quick and dirty implementation of a Vulkan layer to force a specific physical device to be used. This is useful for Vulkan games which do not provide an option to choose the device themselves.

Compiling requires vulkan/vulkan.h, vulkan/vk_layer.h and vulkan/vk_layer_dispatch_table.h. On Debian based systems, you can install these with:

sudo apt-get install libvulkan-dev vulkan-validationlayers-dev

On Fedora, you can install these with:

sudo dnf install vulkan-headers vulkan-validation-layers-devel

Build and install with:

meson builddir --prefix=/usr
meson compile -C builddir
sudo meson install -C builddir

This will install to the system's Vulkan layer directory, /usr/share/vulkan/implicit_layer.d/.

To run a Vulkan application forcing a specific device to be used, launch it with these environment variables:

ENABLE_DEVICE_CHOOSER_LAYER=1 VULKAN_DEVICE_INDEX=<device index>

Replace <device index> with the "GPU id" for the desired device as reported by vulkaninfo (without the layer enabled).

For example:

$ ENABLE_DEVICE_CHOOSER_LAYER=1 VULKAN_DEVICE_INDEX=1 vulkaninfo

should give info for the device which had GPU id 1 when running vulkaninfo without the environment variable set.

The layer can be used with Steam games by setting their launch options to:

ENABLE_DEVICE_CHOOSER_LAYER=1 VULKAN_DEVICE_INDEX=<device index> %command%

If you prefer not to use indexes, you can set VULKAN_DEVICE_INDEX to name:<GPU name fragment>, where is a part of the gpu name. This will make the program use the last gpu that has a name that contains . For example, if you have a gpu named AMD Radeon RX 5700 XT, and set VULKAN_DEVICE_INDEX to name:5700 XT, then this gpu will be selected among others.

You can also set VULKAN_DEVICE_INDEX to letmechoose and a small screen will allow you to choose the gpu to use from a list.

Some games create a lot of processes that have vulkan environment, so they may ask repeatedly what gpu to use, to prevent being asked too much, you can also set VULKAN_DEVICE_INDEX to letmechoose:<some name> and all vulkan instances will use the same device after you choose once, the setting will be save to /tmp/vkdevicechooser/<some name>.