{ hardware.graphics.extraPackages = [ intel-compute-runtime ]; }
```

## Vulkan {#sec-gpu-accel-vulkan}

[Vulkan](https://en.wikipedia.org/wiki/Vulkan_(API)) is a graphics and
compute API for GPUs. It is used directly by games or indirectly though
compatibility layers like
[DXVK](https://github.com/doitsujin/dxvk/wiki).

By default, if [](#opt-hardware.graphics.enable)
is enabled, Mesa is installed and provides Vulkan for supported hardware.

Similar to OpenCL, Vulkan drivers are loaded through the *Installable
Client Driver* (ICD) mechanism. ICD files for Vulkan are JSON files that
specify the path to the driver library and the supported Vulkan version.
All successfully loaded drivers are exposed to the application as
different GPUs. In NixOS, there are two ways to make ICD files visible
to Vulkan applications: an environment variable and a module option.

The first option is through the `VK_ICD_FILENAMES` environment variable.
This variable can contain multiple JSON files, separated by `:`. For
example:

```ShellSession
$ export \
  VK_ICD_FILENAMES=`nix-build '<nixpkgs>' --no-out-link -A amdvlk`/share/vulkan/icd.d/amd_icd64.json
```

The second mechanism is to add the Vulkan driver package to
[](#opt-hardware.graphics.extraPackages).
This links the ICD file under `/run/opengl-driver`, where it will be
visible to the ICD loader.

The proper installation of Vulkan drivers can be verified through the
`vulkaninfo` command of the vulkan-tools package. This command will
report the hardware devices and drivers found, in this example output
amdvlk and radv:

```ShellSession
$ vulkaninfo | grep GPU
                GPU id  : 0 (Unknown AMD GPU)
                GPU id  : 1 (AMD RADV NAVI10 (LLVM 9.0.1))
     ...
GPU0:
        deviceType     = PHYSICAL_DEVICE_TYPE_DISCRETE_GPU
        deviceName     = Unknown AMD GPU
GPU1:
        deviceType     = PHYSICAL_DEVICE_TYPE_DISCRETE_GPU
```

A simple graphical application that uses Vulkan is `vkcube` from the
vulkan-tools package.

### AMD {#sec-gpu-accel-vulkan-amd}

Modern AMD [Graphics Core
Next](https://en.wikipedia.org/wiki/Graphics_Core_Next) (GCN) GPUs are
supported through either radv, which is part of mesa, or the amdvlk
package. Adding the amdvlk package to
[](#opt-hardware.graphics.extraPackages)
makes amdvlk the default driver and hides radv and lavapipe from the device list.
A specific driver can be forced as follows:

```nix
{
  hardware.graphics.extraPackages = [ pkgs.amdvlk ];

  # To enable Vulkan support for 32-bit applications, also add:
  hardware.graphics.extraPackages32 = [ pkgs.driversi686Linux.amdvlk ];

  # Force radv
  environment.variables.AMD_VULKAN_ICD = "RADV";
  # Or
  environment.variables.VK_ICD_FILENAMES = "/run/opengl-driver/share/vulkan/icd.d/radeon_icd.x86_64.json";