[gnome-shell/wip/hadess/always-launch-discrete-gpu] shell-app: Add discrete GPU support for NVidia drivers

[Bastien Nocera <hadess src gnome org>]

commit 752b1df6596fde6ce9b30fbea5af80f454216da1
Author: Bastien Nocera <hadess hadess net>
Date:   Thu Oct 24 14:39:25 2019 +0200

    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

 src/shell-app.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/src/shell-app.c b/src/shell-app.c
index b9ceac34b0..663873cde0 100644
--- a/src/shell-app.c
+++ b/src/shell-app.c
@@ -1309,7 +1309,11 @@ shell_app_launch (ShellApp              *app,
   context = shell_global_create_app_launch_context (global, timestamp, workspace);
   /* 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, "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