The efi boot stub code should only be run if it is enabled

modules/system/boot/loader/efi-boot-stub/efi-boot-stub.nix

@@ -1,9 +1,42 @@
 {pkgs, config, ...}:
 
-###### interface
+with pkgs.lib;
-let
-  inherit (pkgs.lib) mkOption mkIf;
 
+let
+  efiBootStubBuilder = pkgs.substituteAll {
+    src = ./efi-boot-stub-builder.sh;
+    isExecutable = true;
+    inherit (pkgs) bash;
+    path = [pkgs.coreutils pkgs.gnused pkgs.gnugrep pkgs.glibc] ++ (pkgs.stdenv.lib.optionals config.boot.loader.efiBootStub.runEfibootmgr [pkgs.efibootmgr pkgs.module_init_tools]);
+    inherit (config.boot.loader.efiBootStub) efiSysMountPoint runEfibootmgr installStartupNsh efiDisk efiPartition;
+
+    efiShell = if config.boot.loader.efiBootStub.installShell then
+      if pkgs.stdenv.isi686 then
+        pkgs.fetchurl {
+          url = "https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/EdkShellBinPkg/FullShell/Ia32/Shell_Full.efi";
+          sha256 = "1gv6kyaspczdp7x8qnx5x76ilriaygkfs99ay7ihhdi6riclkhfl";
+        }
+      else
+        pkgs.fetchurl {
+          url = "https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/EdkShellBinPkg/FullShell/X64/Shell_Full.efi";
+          sha256 = "1g18z84rlavxr5gsrh2g942rfr6znv9fs3fqww5m7dhmnysgyv8p";
+        }
+    else
+      null;
+
+    kernelFile = platform.kernelTarget;
+    targetArch = if pkgs.stdenv.isi686 then
+      "IA32"
+    else if pkgs.stdenv.isx86_64 then
+      "X64"
+    else
+      throw "Unsupported architecture";
+  };
+
+  # Temporary check, for nixos to cope both with nixpkgs stdenv-updates and trunk
+  platform = pkgs.stdenv.platform;
+in
+{
   options = {
     boot = {
       loader = {
@@ -75,52 +108,8 @@ let
     };
   };
 
-in
+  config = mkIf config.boot.loader.efiBootStub.enable {
-
+    assertions = [ { assertion = ! config.boot.kernelPackages.kernel ? features || config.boot.kernelPackages.kernel.features ? efiBootStub; message = "This kernel does not support the EFI boot stub"; } ];
-###### implementation
-let
-  efiBootStubBuilder = pkgs.substituteAll {
-    src = ./efi-boot-stub-builder.sh;
-    isExecutable = true;
-    inherit (pkgs) bash;
-    path = [pkgs.coreutils pkgs.gnused pkgs.gnugrep pkgs.glibc] ++ (pkgs.stdenv.lib.optionals config.boot.loader.efiBootStub.runEfibootmgr [pkgs.efibootmgr pkgs.module_init_tools]);
-    inherit (config.boot.loader.efiBootStub) efiSysMountPoint runEfibootmgr installStartupNsh efiDisk efiPartition;
-
-    efiShell = if config.boot.loader.efiBootStub.installShell then
-      if pkgs.stdenv.isi686 then
-        pkgs.fetchurl {
-          url = "https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/EdkShellBinPkg/FullShell/Ia32/Shell_Full.efi";
-          sha256 = "1gv6kyaspczdp7x8qnx5x76ilriaygkfs99ay7ihhdi6riclkhfl";
-        }
-      else
-        pkgs.fetchurl {
-          url = "https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2/EdkShellBinPkg/FullShell/X64/Shell_Full.efi";
-          sha256 = "1g18z84rlavxr5gsrh2g942rfr6znv9fs3fqww5m7dhmnysgyv8p";
-        }
-    else
-      null;
-
-    kernelFile = platform.kernelTarget;
-    targetArch = if pkgs.stdenv.isi686 then
-      "IA32"
-    else if pkgs.stdenv.isx86_64 then
-      "X64"
-    else
-      throw "Unsupported architecture";
-  };
-
-  # Temporary check, for nixos to cope both with nixpkgs stdenv-updates and trunk
-  platform = pkgs.stdenv.platform;
-in
-{
-  #assertions = [ { assertion = ! config.boot.kernelPackages.kernel ? features || config.boot.kernelPackages.kernel.features ? efiBootStub; message = "This kernel does not support the EFI boot stub"; } ];
-  
-  require = [
-    options
-
-    # config.system.build
-    # ../system/system-options.nix
-  ];
   
     system = {
       build.installBootLoader = efiBootStubBuilder;
@@ -130,5 +119,6 @@ in
         (isYes "EFI_STUB")
       ];
     };
+  };
 
 }