anchor.diff:      xen
     ] ++ optionals enableIscsi [
       openiscsi
  +  ] ++ optionals enableCeph [
  +    ceph
     ] ++ optionals stdenv.isDarwin [
       libiconv gmp
     ];
  
positive.code: , curl, libiconv, gmp, zfs, parted, bridge-utils, dmidecode
  , enableXen ? false, xen ? null
  , enableIscsi ? false, openiscsi
  }:
  
  with stdenv.lib;
  
negative.code:     "--with-storage-zfs"
    ] ++ optionals enableIscsi [
      "--with-storage-iscsi"
    ] ++ optionals enableCeph [
      "--with-storage-rbd"
    ] ++ optionals stdenv.isDarwin [
      "--with-init-script=none"
    ];
  