1 files changed, 21 insertions, 7 deletions
diff --git a/nixos/modules/system/boot/loader/grub/grub.nix b/nixos/modules/system/boot/loader/grub/grub.nix
index e2cff1c1bd94..42da65857221 100644
--- a/nixos/modules/system/boot/loader/grub/grub.nix
+++ b/nixos/modules/system/boot/loader/grub/grub.nix
@@ -64,9 +64,10 @@ let
       )) + ":" + (makeSearchPathOutput "bin" "sbin" [
         pkgs.mdadm pkgs.utillinux
       ]);
-      font = if lib.last (lib.splitString "." cfg.font) == "pf2"
+      font = if cfg.font == null then ""
+        else (if lib.last (lib.splitString "." cfg.font) == "pf2"
              then cfg.font
-             else "${convertedFont}";
+             else "${convertedFont}");
     });
 
   bootDeviceCounters = fold (device: attr: attr // { "${device}" = (attr."${device}" or 0) + 1; }) {}
@@ -308,10 +309,22 @@ in
         type = types.nullOr types.path;
         example = literalExample "./my-background.png";
         description = ''
-          Background image used for GRUB.  It must be a 640x480,
+          Background image used for GRUB.
+          Set to <literal>null</literal> to run GRUB in text mode.
+
+          <note><para>
+          For grub 1:
+          It must be a 640x480,
           14-colour image in XPM format, optionally compressed with
-          <command>gzip</command> or <command>bzip2</command>.  Set to
-          <literal>null</literal> to run GRUB in text mode.
+          <command>gzip</command> or <command>bzip2</command>.
+          </para></note>
+
+          <note><para>
+          For grub 2:
+          File must be one of .png, .tga, .jpg, or .jpeg. JPEG images must
+          not be progressive.
+          The image will be scaled if necessary to fit the screen.
+          </para></note>
         '';
       };
 
@@ -372,8 +385,9 @@ in
       };
 
       default = mkOption {
-        default = 0;
-        type = types.int;
+        default = "0";
+        type = types.either types.int types.str;
+        apply = toString;
         description = ''
           Index of the default menu item to be booted.
         '';