anchor.diff:  
   # Pass PATH/LD_LIBRARY_PATH to point to current mpirun by default
   , enablePrefix ? false
  +
  +# Enable libfabric support (necessary for Omnipath networks) on x86_64 linux
  +, fabricSupport ? stdenv.isLinux && stdenv.isx86_64
  +
   }:
   
   assert !cudaSupport || cudatoolkit != null;
  
positive.code:     # https://github.com/openucx/ucx
      # https://www.open-mpi.org/faq/?category=buildcuda
      ++ lib.optionals cudaSupport [ "--with-cuda=${cudatoolkit_joined}" "--enable-dlopen" ]
      ;
  
    enableParallelBuilding = true;
  
negative.code: { stdenv, fetchurl, fetchpatch, gfortran, perl, libnl
  , rdma-core, zlib, numactl, libevent, hwloc, pkgsTargetTarget, symlinkJoin
  , libpsm2, libfabric
  
  # Enable CUDA support
  , cudaSupport ? false, cudatoolkit ? null
  