{ platform ? __currentSystem
, configuration
, nixpkgsPath ? ../../nixpkgs
, nixpkgs ? null
}:

rec {

  configComponents = [
    configuration
    (import ./options.nix)
    systemPathList
  ];

  # Make a configuration object from which we can retrieve option
  # values.
  config =
    pkgs.lib.fixOptionSets
      pkgs.lib.newMergeOptionSets
      pkgs configComponents;

  optionDeclarations =
    pkgs.lib.fixOptionSetsFun
      pkgs.lib.filterOptionSets
      pkgs configComponents
      config;

  pkgs = if nixpkgs == null then 
    import "${nixpkgsPath}/pkgs/top-level/all-packages.nix" {system = platform;}
  else nixpkgs;

  manifests = config.installer.manifests; # exported here because nixos-rebuild uses it

  nix = config.environment.nix;

  kernelPackages = config.boot.kernelPackages;

  kernel = kernelPackages.kernel;

  modulesTree = config.system.modulesTree;


  # The initial ramdisk.
  initialRamdiskStuff = import ../boot/boot-stage-1.nix {
    inherit pkgs config;
  };

  initialRamdisk = initialRamdiskStuff.initialRamdisk;


  # NixOS installation/updating tools.
  nixosTools = import ../installer {
    inherit pkgs config;
  };


  # NSS modules.  Hacky!
  nssModules = config.system.nssModules.list;

  nssModulesPath = config.system.nssModules.path;


  # Wrapper around modprobe to set the path to the modules.
  modprobe = config.system.sbin.modprobe;


  # Environment variables for running Nix.
  nixEnvVars = config.nix.envVars;


  # The static parts of /etc.
  etc = config.system.build.etc;

  
  # Font aggregation
  fontDir = config.system.build.x11Fonts;

  
  # The wrapper setuid programs (since we can't have setuid programs
  # in the Nix store).
  wrapperDir = config.system.wrapperDir;
  
  setuidWrapper = import ../helpers/setuid {
    inherit (pkgs) stdenv;
    inherit wrapperDir;
  };


  # A patched `mount' command that looks in a directory in the Nix
  # store instead of in /sbin for mount helpers (like mount.ntfs-3g or
  # mount.cifs).
  mount = config.system.sbin.mount;
  

  # The packages you want in the boot environment.
  # This have to be split up.
  systemPathList = {
    system = {
      overridePath = [
        # Better leave them here - they are small, needed,
        # and hard to refer from anywhere outside.
        modprobe # must take precedence over module_init_tools
        mount # must take precedence over util-linux
        nix
        nixosTools.nixosInstall
        nixosTools.nixosRebuild
        nixosTools.nixosCheckout
        nixosTools.nixosHardwareScan
        nixosTools.nixosGenSeccureKeys
        setuidWrapper
      ];
      path =
        pkgs.lib.optionals (!config.environment.cleanStart) [
        pkgs.bashInteractive # bash with ncurses support
        pkgs.bzip2
        pkgs.coreutils
        pkgs.cpio
        pkgs.curl
        pkgs.e2fsprogs
        pkgs.findutils
        pkgs.glibc # for ldd, getent
        pkgs.gnugrep
        pkgs.gnused
        pkgs.gnutar
        pkgs.grub
        pkgs.gzip
        pkgs.iputils
        pkgs.less
        pkgs.lvm2
        pkgs.man
        pkgs.mdadm
        pkgs.module_init_tools
        pkgs.nano
        pkgs.ncurses
        pkgs.netcat
        pkgs.nettools
        pkgs.ntp
        pkgs.openssh
        pkgs.pciutils
        pkgs.perl
        pkgs.procps
        pkgs.pwdutils
        pkgs.reiserfsprogs
        pkgs.rsync
        pkgs.seccureUser
        pkgs.strace
        pkgs.su
        pkgs.sysklogd
        pkgs.sysvtools
        pkgs.time
        pkgs.udev
        pkgs.upstart
        pkgs.usbutils
        pkgs.utillinux
        pkgs.wirelesstools
        (import ../helpers/info-wrapper.nix {inherit (pkgs) bash texinfo writeScriptBin;})
      ]
      ++ pkgs.lib.optional config.services.bitlbee.enable pkgs.bitlbee
      ++ pkgs.lib.optional config.networking.defaultMailServer.directDelivery pkgs.ssmtp 
      ++ config.environment.extraPackages
      ++ pkgs.lib.optional config.fonts.enableFontDir fontDir

      # NSS modules need to be in `systemPath' so that (i) the builder
      # chroot gets to seem them, and (ii) applications can benefit from
      # changes in the list of NSS modules at run-time, without requiring
      # a reboot.
      ++ nssModules;
    };
  };


  # We don't want to put all of `startPath' and `path' in $PATH, since
  # then we get an embarrassingly long $PATH.  So use the user
  # environment builder to make a directory with symlinks to those
  # packages.
  systemPath = config.system.path;


  defaultShell = config.system.shell;


  # The script that activates the configuration, i.e., it sets up
  # /etc, accounts, etc.  It doesn't do anything that can only be done
  # at boot time (such as start `init').
  activateConfiguration = config.system.activationScripts.script;

  # The shell that we want to use for /bin/sh.
  binsh = pkgs.bashInteractive;


  # The init script of boot stage 2, which is supposed to do
  # everything else to bring up the system.
  bootStage2 = config.system.build.bootStage2;


  # Script to build the Grub menu containing the current and previous
  # system configurations.
  grubMenuBuilder = config.system.build.grubMenuBuilder;


  # Putting it all together.  This builds a store object containing
  # symlinks to the various parts of the built configuration (the
  # kernel, the Upstart services, the init scripts, etc.) as well as a
  # script `switch-to-configuration' that activates the configuration
  # and makes it bootable.
  system = pkgs.checker (pkgs.stdenv.mkDerivation {
    name = "system";
    builder = ./system.sh;
    switchToConfiguration = ./switch-to-configuration.sh;
    inherit (pkgs) grub coreutils gnused gnugrep diffutils findutils upstart;
    grubDevice = config.boot.grubDevice;
    kernelParams =
      config.boot.kernelParams ++ config.boot.extraKernelParams;
    inherit bootStage2;
    inherit activateConfiguration;
    inherit grubMenuBuilder;
    inherit etc;
    inherit systemPath;
    kernel = kernel + "/vmlinuz";
    initrd = initialRamdisk + "/initrd";
    # Most of these are needed by grub-install.
    path = [
      pkgs.coreutils
      pkgs.gnused
      pkgs.gnugrep
      pkgs.findutils
      pkgs.diffutils
      pkgs.upstart # for initctl
    ];
    # !!! wtf does this do???
    children = map (x: ((import ./system.nix) 
      { inherit platform; 
        configuration = x//{boot=((x.boot)//{grubDevice = "";});};}).system) 
      config.nesting.children; 
    configurationName = config.boot.configurationName;
  }) config.environment.checkConfigurationOptions
     optionDeclarations config;

}