diff --git a/pkgs/lib/options.nix b/pkgs/lib/options.nix
new file mode 100644
index 00000000000..e2044807e4d
--- /dev/null
+++ b/pkgs/lib/options.nix
@@ -0,0 +1,100 @@
+let
+
+  mkOption = attrs: attrs // {_type = "option";};
+
+  typeOf = x: if x ? _type then x._type else "";
+
+
+  combine = defs: opts: opts //
+    builtins.listToAttrs (map (defName:
+      { attr = defName;
+        value = 
+          let
+            defValue = builtins.getAttr defName defs;
+            optValue = builtins.getAttr defName opts;
+          in
+          if typeOf defValue == "option"
+          then
+            # `defValue' is an option.
+            if builtins.hasAttr defName opts
+            then builtins.getAttr defName opts
+            else defValue.default
+          else
+            # `defValue' is an attribute set containing options.
+            # So recurse.
+            if builtins.hasAttr defName opts && builtins.isAttrs optValue 
+            then combine defValue optValue
+            else combine defValue {};
+      }
+    ) (builtins.attrNames defs));
+
+
+  testDefs = {
+  
+    time = {
+      timeZone = mkOption {
+        default = "CET";
+        example = "America/New_York";
+        description = "The time zone used when displaying times and dates.";
+      };
+    };
+
+    boot = {
+      kernelModules = mkOption {
+        default = ["mod1"];
+        description = "
+          The set of kernel modules to be loaded in the second stage of
+          the boot process.  That is, these modules are not included in
+          the initial ramdisk, so they'd better not be required for
+          mounting the root file system.  Add them to
+          <option>boot.initrd.extraKernelModules</option> if they are.
+        ";
+      };
+
+      initrd = {
+      
+        kernelModules = mkOption {
+          default = [
+            "ahci"
+            "ata_piix"
+            "pata_marvell"
+            "sd_mod"
+            "sr_mod"
+            "ide-cd"
+            "ide-disk"
+            "ide-generic"
+            "ext3"
+            # Support USB keyboards, in case the boot fails and we only have
+            # a USB keyboard.
+            "ehci_hcd"
+            "ohci_hcd"
+            "usbhid"
+          ];
+          description = "
+            The set of kernel modules in the initial ramdisk used during the
+            boot process.
+          ";
+        };
+        
+      };
+      
+    };
+    
+  };
+
+
+  testOpts = {
+    /*
+    time = {
+      timeZone = "UTC";
+    };
+    */
+    boot = {
+      initrd = {
+        kernelModules = ["foo"];
+        extraKernelModules = ["bar"];
+      };
+    };
+  };
+
+in (combine testDefs testOpts).boot.initrd.kernelModules