nixos/grub: Adds background color and mode options

The background color option is self-explanatory.

The mode is either `normal` or `stretch`, they are as defined by GRUB,
where normal will put the image in the top-left corner of the menu, and
stretch is the default, where it stretches the image without
consideration for the aspect ratio.

 * https://www.gnu.org/software/grub/manual/grub/grub.html#background_005fimage

2 files changed, 35 insertions, 1 deletions

diff --git a/nixos/modules/system/boot/loader/grub/grub.nix b/nixos/modules/system/boot/loader/grub/grub.nix
index 42da65857221..a9c5e8e30d32 100644
--- a/nixos/modules/system/boot/loader/grub/grub.nix
+++ b/nixos/modules/system/boot/loader/grub/grub.nix
@@ -38,6 +38,8 @@ let
     in
     pkgs.writeText "grub-config.xml" (builtins.toXML
     { splashImage = f cfg.splashImage;
+      splashMode = f cfg.splashMode;
+      backgroundColor = f cfg.backgroundColor;
       grub = f grub;
       grubTarget = f (grub.grubTarget or "");
       shell = "${pkgs.runtimeShell}";
@@ -328,6 +330,31 @@ in
         '';
       };
 
+      backgroundColor = mkOption {
+        type = types.nullOr types.string;
+        example = "#7EBAE4";
+        default = null;
+        description = ''
+          Background color to be used for GRUB to fill the areas the image isn't filling.
+
+          <note><para>
+          This options has no effect for GRUB 1.
+          </para></note>
+        '';
+      };
+
+      splashMode = mkOption {
+        type = types.enum [ "normal" "stretch" ];
+        default = "stretch";
+        description = ''
+          Whether to stretch the image or show the image in the top-left corner unstretched.
+
+          <note><para>
+          This options has no effect for GRUB 1.
+          </para></note>
+        '';
+      };
+
       font = mkOption {
         type = types.nullOr types.path;
         default = "${realGrub}/share/grub/unicode.pf2";
diff --git a/nixos/modules/system/boot/loader/grub/install-grub.pl b/nixos/modules/system/boot/loader/grub/install-grub.pl
index d1ff6e6bf525..ea6e56892cb3 100644
--- a/nixos/modules/system/boot/loader/grub/install-grub.pl
+++ b/nixos/modules/system/boot/loader/grub/install-grub.pl
@@ -51,6 +51,8 @@ my $extraEntries = get("extraEntries");
 my $extraEntriesBeforeNixOS = get("extraEntriesBeforeNixOS") eq "true";
 my $extraInitrd = get("extraInitrd");
 my $splashImage = get("splashImage");
+my $splashMode = get("splashMode");
+my $backgroundColor = get("backgroundColor");
 my $configurationLimit = int(get("configurationLimit"));
 my $copyKernels = get("copyKernels") eq "true";
 my $timeout = int(get("timeout"));
@@ -307,10 +309,15 @@ else {
         if ($suffix eq ".jpg") {
             $suffix = ".jpeg";
         }
+		if ($backgroundColor) {
+			$conf .= "
+		    background_color '$backgroundColor'
+		    ";
+		}
         copy $splashImage, "$bootPath/background$suffix" or die "cannot copy $splashImage to $bootPath\n";
         $conf .= "
             insmod " . substr($suffix, 1) . "
-            if background_image " . $grubBoot->path . "/background$suffix; then
+            if background_image --mode '$splashMode' " . $grubBoot->path . "/background$suffix; then
               set color_normal=white/black
               set color_highlight=black/white
             else