mpiCheckPhaseHook: change HYDRA_IFACE to lo0 on Darwin platform

      ;;

    MPICH)

      # Fix to make mpich run in a sandbox

      export HYDRA_IFACE=lo

      export HYDRA_IFACE="@iface@"

      # Disable sysfs cpu topology directory discovery.

      export HWLOC_XMLFILE="@topology@"

      ;;

{ callPackage, makeSetupHook }:

{

  callPackage,

  makeSetupHook,

  stdenv,

}:

makeSetupHook {

  name = "mpi-checkPhase-hook";

  substitutions = {

    iface = if stdenv.hostPlatform.isDarwin then "lo0" else "lo";

    topology = ./topology.xml;

  };

} ./mpi-check-hook.sh