anchor.diff:      "--with-macvtap"
       "--with-virtualport"
       "--with-init-script=redhat"
  +    "--with-storage-zfs"
     ] ++ stdenv.lib.optionals stdenv.isDarwin [
       "--with-init-script=none"
     ];
  
positive.code:     libxslt xhtml1 perlPackages.XMLXPath curl libpcap
    ] ++ stdenv.lib.optionals stdenv.isLinux [
      libpciaccess devicemapper lvm2 utillinux systemd.udev.lib libcap_ng
      libnl numad numactl xen
    ] ++ stdenv.lib.optionals stdenv.isDarwin [
       libiconv gmp
    ];
  
negative.code: , iproute, iptables, readline, lvm2, utillinux, systemd, libpciaccess, gettext
  , libtasn1, ebtables, libgcrypt, yajl, pmutils, libcap_ng
  , dnsmasq, libnl, libpcap, libxslt, xhtml1, numad, numactl, perlPackages
  , curl, libiconv, gmp, xen, zfs
  }:
  # if you update, also bump pythonPackages.libvirt or it will break
  stdenv.mkDerivation rec {
  