vrend_debug: Remove hard coded vrend_use_debug_cb

This was hard coded as zero before and can't be changed at runtime.
Change to use the "VREND_DEBUG" environment variable to control this
behavior.

Signed-off-by: Lepton Wu <lepton@chromium.org>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>

src/vrend_debug.c

@@ -123,6 +123,7 @@ static const struct debug_named_value vrend_debug_options[] = {
    {"gles", dbg_gles, "GLES host specific debug"},
    {"all", dbg_all, "Enable all debugging output"},
    {"guestallow", dbg_allow_guest_override, "Allow the guest to override the debug flags"},
+   {"khr", dbg_khr, "Enable debug via KHR_debug extension"},
    DEBUG_NAMED_VALUE_END
 };
 

src/vrend_debug.h

@@ -49,6 +49,7 @@ enum virgl_debug_flags {
    dbg_all = (1 << 13) - 1,
    dbg_allow_guest_override = 1 << 16,
    dbg_feature_use = 1 << 17,
+   dbg_khr = 1 << 18,
 };
 
 const char *vrend_get_comand_name(enum virgl_context_cmd cmd);

src/vrend_renderer.c

@@ -67,9 +67,6 @@ extern struct virgl_gbm *gbm;
 extern struct virgl_egl *egl;
 #endif
 
-/* debugging via KHR_debug extension */
-int vrend_use_debug_cb = 0;
-
 int use_context = CONTEXT_NONE;
 
 static const uint32_t fake_occlusion_query_samples_passed_default = 1024;
@@ -5759,7 +5756,7 @@ int vrend_renderer_init(struct vrend_if_cbs *cbs, uint32_t flags)
    gl_ver = epoxy_gl_version();
 
    /* enable error output as early as possible */
-   if (vrend_use_debug_cb && epoxy_has_gl_extension("GL_KHR_debug")) {
+   if (vrend_debug(NULL, dbg_khr) && epoxy_has_gl_extension("GL_KHR_debug")) {
       glDebugMessageCallback(vrend_debug_cb, NULL);
       glEnable(GL_DEBUG_OUTPUT);
       glDisable(GL_DEBUG_OUTPUT_SYNCHRONOUS);