<li>LIBGL_DEBUG - If defined debug information will be printed to stderr.
If set to 'verbose' additional information will be printed.
<li>LIBGL_DRIVERS_PATH - colon-separated list of paths to search for DRI drivers
-<li>LIBGL_ALWAYS_INDIRECT - forces an indirect rendering context/connection.
-<li>LIBGL_ALWAYS_SOFTWARE - if set, always use software rendering
+<li>LIBGL_ALWAYS_INDIRECT - if set to `true`, forces an indirect rendering context/connection.
+<li>LIBGL_ALWAYS_SOFTWARE - if set to `true`, always use software rendering
<li>LIBGL_NO_DRAWARRAYS - if set do not use DrawArrays GLX protocol (for debugging)
<li>LIBGL_SHOW_FPS - print framerate to stdout based on the number of glXSwapBuffers
calls per second.
<li>MESA_NO_MMX - if set, disables Intel MMX optimizations
<li>MESA_NO_3DNOW - if set, disables AMD 3DNow! optimizations
<li>MESA_NO_SSE - if set, disables Intel SSE optimizations
-<li>MESA_NO_ERROR - if set error checking is disabled as per KHR_no_error.
+<li>MESA_NO_ERROR - if set to 1, error checking is disabled as per KHR_no_error.
This will result in undefined behaviour for invalid use of the api, but
can reduce CPU use for apps that are known to be error free.</li>
<li>MESA_DEBUG - if set, error messages are printed to stderr. For example,
<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>
<li>state - emit messages about state flag tracking</li>
- <li>stats - enable statistics counters. you probably actually want perfmon or intel_gpu_top instead.</li>
<li>sync - after sending each batch, emit a message and wait for that batch to finish rendering</li>
<li>tcs - dump shader assembly for tessellation control shaders</li>
<li>tes - dump shader assembly for tessellation evaluation shaders</li>
<li>tex - emit messages about textures.</li>
<li>urb - emit messages about URB setup</li>
- <li>vec4 - force vec4 mode in vertex shader</li>
<li>vert - emit messages about vertex assembly</li>
<li>vs - dump shader assembly for vertex shaders</li>
</ul>
+<li>INTEL_SCALAR_VS (or TCS, TES, GS) - force scalar/vec4 mode for a shader stage (Gen8-9 only)</li>
<li>INTEL_PRECISE_TRIG - if set to 1, true or yes, then the driver prefers
accuracy over performance in trig functions.</li>
</ul>
Use kill -10 <pid> to toggle the hud as desired.
<li>GALLIUM_HUD_DUMP_DIR - specifies a directory for writing the displayed
hud values into files.
-<li>GALLIUM_DRIVER - useful in combination with LIBGL_ALWAYS_SOFTWARE=1 for
+<li>GALLIUM_DRIVER - useful in combination with LIBGL_ALWAYS_SOFTWARE=true for
choosing one of the software renderers "softpipe", "llvmpipe" or "swr".
<li>GALLIUM_LOG_FILE - specifies a file for logging all errors, warnings, etc.
rather than stderr.
(will often result in incorrect rendering).
<li>SVGA_DEBUG - for dumping shaders, constant buffers, etc. See the code
for details.
+<li>SVGA_EXTRA_LOGGING - if set, enables extra logging to the vmware.log file,
+such as the OpenGL program's name and command line arguments.
<li>See the driver code for other, lesser-used variables.
</ul>