Bug 1730936 - Use EGL_DRM_RENDER_NODE_FILE_EXT in glxtest, r=gfx-reviewers,aosmond

We have a custom render node discovery code (needed for DMABUF) that
predates the `EGL_DRM_RENDER_NODE_FILE_EXT` extension. It has additional
value that it helps us discover the right vendor and device ID on
multi-GPU setups (there's a EGL extension far that backing, but
not ready yet).
In case our custom code fails - notably split display/render SoCs,
which are common in the ARM world - lets use
`EGL_DRM_RENDER_NODE_FILE_EXT` as fallback. This will ensure we
get a valid render node path on all devices, assuming the driver
supports that extension right. These SoCs are usually no multi-GPU
systems. If they are, we still don't get the right IDs - but an
extension for that is in the making.

Note: Mesa does *not* implement this right for such SoCs, i.e. it
will fail just as our own custom code. However, there's a MR in
review - once it lands, things should start working, see
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12796

Depends on D134254

Differential Revision: https://phabricator.services.mozilla.com/D134322

toolkit/xre/glxtest.cpp

@@ -111,6 +111,7 @@ typedef void* (*PFNEGLGETPROCADDRESS)(const char*);
 #define EGL_OPENGL_API 0x30A2
 #define EGL_DEVICE_EXT 0x322C
 #define EGL_DRM_DEVICE_FILE_EXT 0x3233
+#define EGL_DRM_RENDER_NODE_FILE_EXT 0x3377
 
 // stuff from xf86drm.h
 #define DRM_NODE_RENDER 2
@@ -350,11 +351,11 @@ static bool device_has_name(const drmDevice* device, const char* name) {
   return false;
 }
 
-static void get_render_name(const char* name) {
+static bool get_render_name(const char* name) {
   void* libdrm = dlopen(LIBDRM_FILENAME, RTLD_LAZY);
   if (!libdrm) {
     record_warning("Failed to open libdrm");
-    return;
+    return false;
   }
 
   typedef int (*DRMGETDEVICES2)(uint32_t, drmDevicePtr*, int);
@@ -369,7 +370,7 @@ static void get_render_name(const char* name) {
     record_warning(
         "libdrm missing methods for drmGetDevices2 or drmFreeDevice");
     dlclose(libdrm);
-    return;
+    return false;
   }
 
   uint32_t flags = 0;
@@ -377,20 +378,20 @@ static void get_render_name(const char* name) {
   if (devices_len < 0) {
     record_warning("drmGetDevices2 failed");
     dlclose(libdrm);
-    return;
+    return false;
   }
   drmDevice** devices = (drmDevice**)calloc(devices_len, sizeof(drmDevice*));
   if (!devices) {
     record_warning("Allocation error");
     dlclose(libdrm);
-    return;
+    return false;
   }
   devices_len = drmGetDevices2(flags, devices, devices_len);
   if (devices_len < 0) {
     free(devices);
     record_warning("drmGetDevices2 failed");
     dlclose(libdrm);
-    return;
+    return false;
   }
 
   const drmDevice* match = nullptr;
@@ -401,6 +402,7 @@ static void get_render_name(const char* name) {
     }
   }
 
+  bool result = false;
   if (!match) {
     record_warning("Cannot find DRM device");
   } else if (!(match->available_nodes & (1 << DRM_NODE_RENDER))) {
@@ -411,6 +413,7 @@ static void get_render_name(const char* name) {
         "MESA_VENDOR_ID\n0x%04x\n"
         "MESA_DEVICE_ID\n0x%04x\n",
         match->deviceinfo.pci->vendor_id, match->deviceinfo.pci->device_id);
+    result = true;
   }
 
   for (int i = 0; i < devices_len; i++) {
@@ -419,6 +422,7 @@ static void get_render_name(const char* name) {
   free(devices);
 
   dlclose(libdrm);
+  return result;
 }
 #endif
 
@@ -543,8 +547,12 @@ static bool get_gles_status(EGLDisplay dpy,
 #ifdef MOZ_WAYLAND
       const char* deviceString =
           eglQueryDeviceStringEXT(device, EGL_DRM_DEVICE_FILE_EXT);
-      if (deviceString) {
-        get_render_name(deviceString);
+      if (!deviceString || !get_render_name(deviceString)) {
+        const char* renderNodeString =
+            eglQueryDeviceStringEXT(device, EGL_DRM_RENDER_NODE_FILE_EXT);
+        if (renderNodeString) {
+          record_value("DRM_RENDERDEVICE\n%s\n", renderNodeString);
+        }
       }
 #endif
     }