{ config, pkgs, lib, ... }:
with lib; {

  options.systemd.services = lib.mkOption {
    type = types.attrsOf (types.submodule ({ name, config, ... }: {
      options.genode = {

        enable = lib.mkEnableOption "systemd unit to a Genode subsystem translation";

        interface = lib.mkOption {
          type = with types; nullOr str;
          default = null;
          example = "eth0";
          description = ''
            Grant access to an IP stack for this interface.
            Only UDP and TCP are supported. No raw device access.
          '';
        };

        extraVfs = lib.mkOption {
          type = with types; nullOr path;
          default = null;
          description = ''
            Extra configuration to be appended to the VFS of the service.
            Dhall type is Prelude/XML/Type.
          '';
        };

        ramQuota = lib.mkOption {
          type = types.ints.unsigned;
          default = 16;
          description = "RAM quota in MiB";
        };

      };
    }));
  };

  config = {

    services.klogd.enable = false;
    # The default is determined by checking the Linux version
    # which cannot be evaluated here.

    genode.init.children = mapAttrs' (name: service:
      let name' = "services." + name;
      in {
        name = name';
        value = {
          inputs = with pkgs;
            with genodePackages; [
              bash
              cached_fs_rom
              libc
              posix
              vfs
              vfs_pipe
            ];
          configFile = let
            args = lib.strings.splitString " "
              (toString service.serviceConfig.ExecStart);
            binary = builtins.head args;
            args' = ''[ "${concatStringsSep ''", "'' (builtins.tail args)}" ]'';
            # TODO: service.environment;
            interface = if service.genode.interface == null then
              "None Text"
            else
              ''Some "${service.genode.interface}"'';
          in pkgs.writeText "${name'}.dhall" ''
            ${./systemd-runner.dhall} {
            , args = ${args'}
            , binary = "${binary}"
            , coreutils = "${pkgs.coreutils}"
            , extraVfs = ${
              if service.genode.extraVfs == null then
                "[] : List (env:DHALL_PRELUDE).XML.Type"
              else
                service.genode.extraVfs
            }
            , interface = ${interface}
            , ramQuotaMiB = ${toString service.genode.ramQuota}
            }
          '';
        };
      }) (filterAttrs (name: service: service.genode.enable)
        config.systemd.services);

  };

}