Add driver override to envvars.rst

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6911>

diff --git a/docs/envvars.rst b/docs/envvars.rst
index fa414bd..2395406 100644 (file)
--- a/docs/envvars.rst
+++ b/docs/envvars.rst
@@ -180,6 +180,8 @@ Core Mesa environment variables
       instance version as advertised by ``vkEnumerateInstanceVersion``
    -  This can be very useful for debugging but some features may not be
       implemented correctly. (For developers only)
+``MESA_LOADER_DRIVER_OVERRIDE``
+   chooses a different driver binary such as ``etnaviv`` or ``zink``.
 
 NIR passes environment variables
 --------------------------------