D3D12
=====

Overview
--------

The D3D12 driver is a Gallium driver that emits API calls for Microsoft's
:abbr:`D3D12 (Direct3D 12)` API instead of targeting a specific GPU
architecture. This can be used to get full desktop OpenGL 3.3 support on
devices that only support D3D12.

Debugging
---------

There's a few tools that are useful for debugging D3D12, such as these
environment variables:

.. envvar:: D3D12_DEBUG

   Accepts the following comma-separated list of flags:

   ``verbose``
      Enable verbose output to stdout
   ``blit``
      Trace blit and copy resource calls
   ``experimental``
      Enable experimental shader models feature
   ``dxil``
      Dump DXIL during program compile
   ``disass``
      Dump disassambly of created DXIL shader
   ``res``
      Debug resources
   ``debuglayer``
      Enable `debug layer`_
   ``gpuvalidator``
      Enable `GPU validator`_

.. envvar:: DXIL_DEBUG

   Accepts the following comma-separated list of flags:

   ``verbose``
      Enable verbose output to stdout
   ``dump_blob``
      Write shader blobs
   ``trace``
      Trace instruction conversion
   ``dump_module``
      dump module tree to stderr

.. _debug layer: https://learn.microsoft.com/en-us/windows/win32/direct3d12/understanding-the-d3d12-debug-layer
.. _GPU validator: https://learn.microsoft.com/en-us/windows/win32/direct3d12/using-d3d12-debug-layer-gpu-based-validation

Utilities
---------

Environment variables that control the behavior of the D3D12 driver.

.. envvar:: MESA_D3D12_DEFAULT_ADAPTER_NAME

   Specifies a substring to search for when choosing a default adapter to
   run on. The first adapter matching the substring is chosen. The substring
   is not case sensitive.