anchor.diff:      gid = (import ../system/ids.nix).gids.haldaemon;
     };
   
  +  fdi =
  +    if cfg.extraFdi == [] then
  +      hal + "/share/hal/fdi"
  +    else
  +      pkgs.buildEnv {
  +        name = "hal-fdi";
  +        pathsToLink = [ "/preprobe" "/information" "/policy" ];
  +        paths = [ (hal + "/share/hal/fdi") ] ++ cfg.extraFdi;
  +      };
   
     job = {
       name = "hal";
  
positive.code:           rm -f /var/cache/hald/fdi-cache
  
        end script
  
        respawn ${hal}/sbin/hald --daemon=no
      '';
  
negative.code:           default = true;
            description = "
              Whether to start the HAL daemon.
            ";
          };
  
          extraFdi = mkOption {
            default = [];
            example = [ "/nix/store/.../fdi" ];
            description = "
              Extend HAL daemon configuration with additionnal paths.
            ";
          };
        };
  