NVK
===

NVK is a Vulkan driver for NVIDIA GPUs.

Hardware support
----------------

NVK currently supports Turing (RTX 20XX and GTX 16XX) and later GPUs.
Eventually, we plan to support as far back as Kepler (GeForce 600 and 700
series) GPUs but anything pre-Turing is currently disabled by default.

Kernel requirements
-------------------

NVK requires at least a Linux 6.6 kernel

Conformance status:
-------------------

NVK is a conformant Vulkan 1.3 implementation for all Turing (RTX 20XX and
GTX 16XX) and later GPUs.

Debugging
---------

Here are a few environment variable debug environment variables
specific to NVK:

.. envvar:: NAK_DEBUG

   a comma-separated list of named flags affecting the NVK back-end shader
   compiler:

   ``print``
      Prints the shader at various stages of the compile pipeline
   ``serial``
      Forces serial instruction execution; this is often useful for
      debugging or working around dependency bugs
   ``spill``
      Forces the GPR file to a minimal size to test the spilling code
   ``annotate``
      Adds extra annotation instructions to the IR to track information
      from various compile passes

.. envvar:: NVK_DEBUG

   a comma-separated list of named flags, which do various things:

   ``push``
      Dumps all pushbufs to stderr on submit.  This requires that
      ``push_sync`` also be set.
   ``push_sync``
      Waits for submit to complete before continuing
   ``zero_memory``
      Zeros all VkDeviceMemory objects upon creation
   ``vm``
      Logs VM binds and unbinds
   ``no_cbuf``
      Disables automatic promotion of UBOs to constant buffers

.. envvar:: NVK_I_WANT_A_BROKEN_VULKAN_DRIVER

   If defined to ``1`` or ``true``, this will enable enumeration of all
   GPUs Kepler and later, including GPUs for which hardware support is
   poorly tested or completely broken.  This is intended for developer use
   only.

Hardware Documentation
----------------------

What little documentation we have can be found in the `NVIDIA open-gpu-doc
repository <https://github.com/NVIDIA/open-gpu-doc>`__.  The majority of
our documentation comes in the form of class headers which describe the
class state registers.
