mesa: document _mesa_extension_override_* variables

Currently there are no users of these outside of extensions.c.
Provide some information why they exist and how to use them.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Andres Gomez <agomez@igalia.com>

diff --git a/src/mesa/main/extensions.h b/src/mesa/main/extensions.h
index 59761bf..159610b 100644 (file)
--- a/src/mesa/main/extensions.h
+++ b/src/mesa/main/extensions.h
@@ -106,6 +106,15 @@ _mesa_has_##name_str(const struct gl_context *ctx) \
 #include "extensions_table.h"
 #undef EXT
 
+/* Sometimes the driver wants to query the extension override status before
+ * a context is created. These variables are filled with extension override
+ * information before context creation.
+ *
+ * This can be useful during extension bring-up when an extension is
+ * partially implemented, but cannot yet be advertised as supported.
+ *
+ * Use it with care and keep access read-only.
+ */
 extern struct gl_extensions _mesa_extension_override_enables;
 extern struct gl_extensions _mesa_extension_override_disables;