gpm: Depend on /dev/input/mice

nixos/modules/services/hardware/udev.nix

@@ -20,6 +20,9 @@ let
     # Miscellaneous devices.
     KERNEL=="kvm",                  MODE="0666"
     KERNEL=="kqemu",                MODE="0666"
+
+    # Needed for gpm.
+    KERNEL=="input/mice", TAG+="systemd"
   '';
 
   # Perform substitutions in all udev rules files.

nixos/modules/services/ttys/gpm.nix

@@ -44,7 +44,7 @@ in
       { description = "Console Mouse Daemon";
 
         wantedBy = [ "multi-user.target" ];
-        requires = [ "getty.target" ];
+        requires = [ "dev-input-mice.device" ];
 
         serviceConfig.ExecStart = "@${pkgs.gpm}/sbin/gpm gpm -m /dev/input/mice -t ${cfg.protocol}";
         serviceConfig.Type = "forking";