nixos GDM: fix #19896

- As noted on github, GDM needs different parameters for X.
- Making xserverArgs a true list instead of concat-string helps to
  filter it and it feels more correct anyway.
- Tested: gdm+gnome, lightdm+gnome.  There seems to be no logout option
  in gnome, and gdm doesn't offer other sessions, but maybe these are normal.

1 files changed, 6 insertions, 1 deletions

diff --git a/nixos/modules/services/x11/display-managers/gdm.nix b/nixos/modules/services/x11/display-managers/gdm.nix
index d3aa63fd428..6c63fede857 100644
--- a/nixos/modules/services/x11/display-managers/gdm.nix
+++ b/nixos/modules/services/x11/display-managers/gdm.nix
@@ -92,10 +92,15 @@ in
 
     users.extraGroups.gdm.gid = config.ids.gids.gdm;
 
+    # GDM needs different xserverArgs, presumable because using wayland by default.
+    services.xserver.tty = null;
+    services.xserver.display = null;
+
     services.xserver.displayManager.job =
       {
         environment = {
-          GDM_X_SERVER_EXTRA_ARGS = "${cfg.xserverArgs}";
+          GDM_X_SERVER_EXTRA_ARGS = toString
+            (filter (arg: arg != "-terminate") cfg.xserverArgs);
           GDM_SESSIONS_DIR = "${cfg.session.desktops}";
           # Find the mouse
           XCURSOR_PATH = "~/.icons:${config.system.path}/share/icons";