anchor.diff:  	      {pkgs, config, ...}:
   	      
   	      {
  -	        # Make the Nix store in this VM writable using AUFS.  Use Linux
  -                # 2.6.27 because 2.6.32 doesn't work (probably we need AUFS2).
  -                # This should probably be moved to qemu-vm.nix.
  -
  -                boot.kernelPackages = (if pkgs ? linuxPackages then
  -                  pkgs.linuxPackages_2_6_27 else pkgs.kernelPackages_2_6_27);
  -                boot.extraModulePackages = [ config.boot.kernelPackages.aufs ];
  -                boot.initrd.availableKernelModules = [ "aufs" ];
  -	      
  -                boot.initrd.postMountCommands =
  -                  ''
  -                    mkdir /mnt-store-tmpfs
  -                    mount -t tmpfs -o "mode=755" none /mnt-store-tmpfs
  -                    mount -t aufs -o dirs=/mnt-store-tmpfs=rw:$targetRoot/nix/store=rr none $targetRoot/nix/store
  -                  '';
  -
  +	        virtualisation.writableStore = true;
  +		
                   services.dbus.enable = true;
                   services.dbus.packages = [ disnix ];
   	    
  
positive.code: 	      {pkgs, config, ...}:
  	      
  	      {
  	        # Make the Nix store in this VM writable using AUFS.  Use Linux
                  # 2.6.27 because 2.6.32 doesn't work (probably we need AUFS2).
                  # This should probably be moved to qemu-vm.nix.
  
                  boot.kernelPackages = (if pkgs ? linuxPackages then
                    pkgs.linuxPackages_2_6_27 else pkgs.kernelPackages_2_6_27);
                  boot.extraModulePackages = [ config.boot.kernelPackages.aufs ];
                  boot.initrd.availableKernelModules = [ "aufs" ];
  	      
                  boot.initrd.postMountCommands =
                    ''
                      mkdir /mnt-store-tmpfs
                      mount -t tmpfs -o "mode=755" none /mnt-store-tmpfs
                      mount -t aufs -o dirs=/mnt-store-tmpfs=rw:$targetRoot/nix/store=rr none $targetRoot/nix/store
                    '';
  		  
  	        environment.systemPackages = [ disnix DisnixWebService pkgs.stdenv ];
  	      };
  	  };	    
  
negative.code:     tests = 
        { nixos ? /etc/nixos/nixos
        , disnix ? (import ../../disnix/trunk/release.nix {}).build {}
        , disnix_activation_scripts ? (import ../../disnix-activation-scripts/trunk/release.nix {}).build {}
        }:
        
        let
  