anchor.diff:        fi
       '';
   
  +  # After booting, register the closure of the paths in
  +  # `virtualisation.pathsInNixDB' in the Nix database in the VM.  This
  +  # allows Nix operations to work in the VM.  The path to the
  +  # registration file is passed through the kernel command line to
  +  # allow `system.build.toplevel' to be included.  (If we had a direct
  +  # reference to ${regInfo} here, then we would get a cyclic
  +  # dependency.)
  +  boot.postBootCommands =
  +    ''
  +      ( source /proc/cmdline
  +        ${config.environment.nix}/bin/nix-store --load-db < $regInfo
  +      )
  +    '';
  +      
  +  virtualisation.pathsInNixDB = [ config.system.build.toplevel ];
  +  
     # Mount the host filesystem via CIFS, and bind-mount the Nix store
     # of the host into our own filesystem.  We use mkOverride to allow
     # this module to be applied to "normal" NixOS system configuration,
  
positive.code:         default = true;
          description =
            ''
              Whether to run qemu with a graphics window, or access
              the guest computer serial port through the host tty.
            '';
        };
  
    };
  
    cfg = config.virtualisation;
  
negative.code:         options = "bind";
          neededForBoot = true;
        }
      ];
  
    # Starting DHCP brings down eth0, which kills the connection to the
  