shell-app: Add discrete GPU support for NVidia drivers

Add the necessary environment variables that would make offloading to
the NVidia "secondary" drivers work as expected.

Closes: https://gitlab.gnome.org/GNOME/gnome-shell/issues/1810

js/ui/appDisplay.js

@@ -2513,13 +2513,15 @@ var AppIconMenu = class AppIconMenu extends PopupMenu.PopupMenu {
                 this._appendSeparator();
             }
 
+            let wantsDiscreteGpu = appInfo.get_boolean("PreferRunOnDiscreteGPU") ||
+                appInfo.get_boolean("X-KDE-RunOnDiscreteGpu");
             if (discreteGpuAvailable &&
-                this._source.app.state == Shell.AppState.STOPPED &&
-                !actions.includes('activate-discrete-gpu')) {
+                !wantsDiscreteGpu &&
+                this._source.app.state == Shell.AppState.STOPPED) {
                 this._onDiscreteGpuMenuItem = this._appendMenuItem(_("Launch using Dedicated Graphics Card"));
                 this._onDiscreteGpuMenuItem.connect('activate', () => {
                     this._source.animateLaunch();
-                    this._source.app.launch(0, -1, true);
+                    this._source.app.launch(0, -1, Shell.AppGpuSelection.DISCRETE);
                     this.emit('activate-window', null);
                 });
             }
@@ -2528,8 +2530,7 @@ var AppIconMenu = class AppIconMenu extends PopupMenu.PopupMenu {
                 let action = actions[i];
                 let item = this._appendMenuItem(appInfo.get_action_name(action));
                 item.connect('activate', (emitter, event) => {
-                    if (action == 'new-window' ||
-                        action == 'activate-discrete-gpu')
+                    if (action == 'new-window')
                         this._source.animateLaunch();
 
                     this._source.app.launch_action(action, event.get_time(), -1);

src/shell-app.c

@@ -509,7 +509,7 @@ shell_app_activate_full (ShellApp      *app,
       case SHELL_APP_STATE_STOPPED:
         {
           GError *error = NULL;
-          if (!shell_app_launch (app, timestamp, workspace, FALSE, &error))
+          if (!shell_app_launch (app, timestamp, workspace, SHELL_APP_GPU_SELECTION_AUTO, &error))
             {
               char *msg;
               msg = g_strdup_printf (_("Failed to launch “%s”"), shell_app_get_name (app));
@@ -584,7 +584,7 @@ shell_app_open_new_window (ShellApp      *app,
    * instance (Firefox).  There are a few less-sensical cases such
    * as say Pidgin.
    */
-  shell_app_launch (app, 0, workspace, FALSE, NULL);
+  shell_app_launch (app, 0, workspace, SHELL_APP_GPU_SELECTION_AUTO, NULL);
 }
 
 /**
@@ -1255,18 +1255,36 @@ wait_pid (GDesktopAppInfo *appinfo,
   g_child_watch_add (pid, (GChildWatchFunc) g_spawn_close_pid, NULL);
 }
 
+static gboolean
+get_with_discrete_gpu (ShellApp             *app,
+                       ShellAppGpuSelection  discrete_gpu)
+{
+  switch (discrete_gpu)
+    {
+      case SHELL_APP_GPU_SELECTION_INTEGRATED:
+        return FALSE;
+      case SHELL_APP_GPU_SELECTION_DISCRETE:
+        return TRUE;
+      case SHELL_APP_GPU_SELECTION_AUTO:
+        return g_desktop_app_info_get_boolean (app->info, "PreferRunOnDiscreteGPU") ||
+               g_desktop_app_info_get_boolean (app->info, "X-KDE-RunOnDiscreteGpu");
+      default:
+        g_assert_not_reached();
+    }
+}
+
 /**
  * shell_app_launch:
  * @timestamp: Event timestamp, or 0 for current event timestamp
  * @workspace: Start on this workspace, or -1 for default
- * @discrete_gpu: Whether to start on the discrete GPU
+ * @discrete_gpu: the preferred GPU to launch the application on.
  * @error: A #GError
  */
 gboolean
 shell_app_launch (ShellApp              *app,
                   guint                  timestamp,
                   int                    workspace,
-                  gboolean      discrete_gpu,
+                  ShellAppGpuSelection   discrete_gpu,
                   GError               **error)
 {
   ShellGlobal *global;
@@ -1289,8 +1307,13 @@ shell_app_launch (ShellApp     *app,
 
   global = shell_global_get ();
   context = shell_global_create_app_launch_context (global, timestamp, workspace);
-  if (discrete_gpu)
+  /* FIXME: this should probably check whether we're on a dual-GPU system */
+  if (get_with_discrete_gpu (app, discrete_gpu))
+    {
       g_app_launch_context_setenv (context, "DRI_PRIME", "1");
+      g_app_launch_context_setenv (context, "__NV_PRIME_RENDER_OFFLOAD", "1");
+      g_app_launch_context_setenv (context, "__GLX_VENDOR_LIBRARY_NAME", "nvidia");
+    }
 
   /* Set LEAVE_DESCRIPTORS_OPEN in order to use an optimized gspawn
    * codepath. The shell's open file descriptors should be marked CLOEXEC

src/shell-app.h

@@ -18,6 +18,12 @@ typedef enum {
   SHELL_APP_STATE_RUNNING
 } ShellAppState;
 
+typedef enum {
+  SHELL_APP_GPU_SELECTION_AUTO       = -1,
+  SHELL_APP_GPU_SELECTION_INTEGRATED = 0,
+  SHELL_APP_GPU_SELECTION_DISCRETE   = 1
+} ShellAppGpuSelection;
+
 const char *shell_app_get_id (ShellApp *app);
 
 GDesktopAppInfo *shell_app_get_app_info (ShellApp *app);
@@ -54,7 +60,7 @@ gboolean shell_app_is_on_workspace (ShellApp *app, MetaWorkspace *workspace);
 gboolean shell_app_launch (ShellApp               *app,
                            guint                  timestamp,
                            int                    workspace,
-                           gboolean      discrete_gpu,
+                           ShellAppGpuSelection   discrete_gpu,
                            GError               **error);
 
 void shell_app_launch_action (ShellApp        *app,