anchor.diff:            default = true;
             description = "
               Whether to start the HAL daemon.
  +          ";
  +        };
  +
  +        extraFdi = mkOption {
  +          default = [];
  +          example = [ "/nix/store/.../fdi" ];
  +          description = "
  +            Extend HAL daemon configuration with additionnal paths.
             ";
           };
         };
  
positive.code:           rm -f /var/cache/hald/fdi-cache
  
        end script
  
        respawn ${hal}/sbin/hald --daemon=no
      '';
  
negative.code:     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";
  