<li> Mesa may not really implement all the features of the given version.
(for developers only)
</ul>
+<li>MESA_GLES_VERSION_OVERRIDE - changes the value returned by
+glGetString(GL_VERSION) for OpenGL ES.
+<ul>
+<li> The format should be MAJOR.MINOR
+<li> Examples: 2.0, 3.0, 3.1
+<li> Mesa may not really implement all the features of the given version.
+(for developers only)
+</ul>
<li>MESA_GLSL_VERSION_OVERRIDE - changes the value returned by
glGetString(GL_SHADING_LANGUAGE_VERSION). Valid values are integers, such as
"130". Mesa will not really implement all the features of the given language version
<li>blorp - emit messages about the blorp operations (blits & clears)</li>
<li>nodualobj - suppress generation of dual-object geometry shader code</li>
<li>optimizer - dump shader assembly to files at each optimization pass and iteration that make progress</li>
+ <li>vec4 - force vec4 mode in vertex shader</li>
+ <li>spill_fs - force spilling of all registers in the scalar backend (useful to debug spilling code)</li>
+ <li>spill_vec4 - force spilling of all registers in the vec4 backend (useful to debug spilling code)</li>
</ul>
</ul>
<li>LP_PERF - a comma-separated list of options to selectively no-op various
parts of the driver. See the source code for details.
<li>LP_NUM_THREADS - an integer indicating how many threads to use for rendering.
- Zero turns of threading completely. The default value is the number of CPU
+ Zero turns off threading completely. The default value is the number of CPU
cores present.
</ul>
</ul>
+<h3>VC4 driver environment variables</h3>
+<ul>
+<li>VC4_DEBUG - a comma-separated list of named flags, which do various things:
+<ul>
+ <li>cl - dump command list during creation</li>
+ <li>qpu - dump generated QPU instructions</li>
+ <li>qir - dump QPU IR during program compile</li>
+ <li>nir - dump NIR during program compile</li>
+ <li>tgsi - dump TGSI during program compile</li>
+ <li>shaderdb - dump program compile information for shader-db analysis</li>
+ <li>perf - print during performance-related events</li>
+ <li>norast - skip actual hardware execution of commands</li>
+ <li>always_flush - flush after each draw call</li>
+ <li>always_sync - wait for finish after each flush</li>
+ <li>dump - write a GPU command stream trace file (VC4 simulator only)</li>
+</ul>
+</ul>
+
+
<p>
Other Gallium drivers have their own environment variables. These may change
frequently so the source code should be consulted for details.