migrate to nixos modules

common/boot/efi.nix

@@ -1,18 +1,28 @@
-{ config, pkgs, ... }:
+{ lib, config, pkgs, ... }:
 
-{
-  # Use GRUB2 for EFI
-  boot.loader = {
-    efi.canTouchEfiVariables = true;
-    grub = {
-      enable = true;
-      device = "nodev";
-      version = 2;
-      efiSupport = true;
-      useOSProber = true;
-#      memtest86.enable = true;
-      configurationLimit = 20;
-      theme = pkgs.nixos-grub2-theme;
+with lib;
+let
+  cfg = config.efi;
+in {
+  options.efi = {
+    enable = mkEnableOption "enable efi boot";
+  };
+
+  config = mkIf cfg.enable {
+    # Use GRUB2 for EFI
+    boot.loader = {
+      efi.canTouchEfiVariables = true;
+      timeout = 2;
+      grub = {
+        enable = true;
+        device = "nodev";
+        version = 2;
+        efiSupport = true;
+        useOSProber = true;
+#       memtest86.enable = true;
+        configurationLimit = 20;
+        theme = pkgs.nixos-grub2-theme;
+      };
     };
   };
 }