anchor.diff:  , pkg-config, makeWrapper, libtool, autoconf, automake, fetchpatch
   , coreutils, libxml2, gnutls, perl, python2, attr
   , iproute2, iptables, readline, lvm2, util-linux, systemd, libpciaccess, gettext
  -, libtasn1, ebtables, libgcrypt, yajl, pmutils, libcap_ng, libapparmor
  +, libtasn1, libgcrypt, yajl, pmutils, libcap_ng, libapparmor
   , dnsmasq, libnl, libpcap, libxslt, xhtml1, numad, numactl, perlPackages
   , curl, libiconv, gmp, zfs, parted, bridge-utils, dmidecode, glib, rpcsvc-proto, libtirpc
   , enableXen ? false, xen ? null
  
positive.code:   ] ++ optionals stdenv.isLinux [
      "QEMU_BRIDGE_HELPER=/run/wrappers/bin/qemu-bridge-helper"
      "QEMU_PR_HELPER=/run/libvirt/nix-helpers/qemu-pr-helper"
      "EBTABLES_PATH=${ebtables}/bin/ebtables-legacy"
      "CFLAGS=-I${libtirpc.dev}/include/tirpc"
      "--with-attr"
      "--with-apparmor"
  
negative.code: 
    preConfigure = ''
      ${ optionalString (!buildFromTarball) "./bootstrap --no-git --gnulib-srcdir=$(pwd)/.gnulib" }
      PATH=${lib.makeBinPath ([ dnsmasq ] ++ optionals stdenv.isLinux [ iproute2 iptables lvm2 systemd numad ] ++ optionals enableIscsi [ openiscsi ])}:$PATH
      # the path to qemu-kvm will be stored in VM's .xml and .save files
      # do not use "''${qemu_kvm}/bin/qemu-kvm" to avoid bound VMs to particular qemu derivations
      substituteInPlace src/lxc/lxc_conf.c \
  