anchor.diff:              --add-flags "-L $COREDIR/${d2u core}_libretro${stdenv.hostPlatform.extensions.sharedLibrary} $@"
           '';
   
  +        enableParallelBuilding = true;
  +
           passthru = {
             inherit core;
             libretroCore = "/lib/retroarch/cores";
  
positive.code:     description = "Port of MAME ~2003 to libretro";
      license = "MAME";
      makefile = "Makefile";
    };
  
    mame2003-plus = mkLibRetroCore {
  
negative.code:     license = "MAME";
      makefile = "Makefile";
      makeFlags = lib.optionals stdenv.hostPlatform.isAarch64 [ "PTR64=1" "ARM_ENABLED=1" "X86_SH2DRC=0" "FORCE_DRC_C_BACKEND=1" ];
      enableParallelBuilding = false;
    };
  
    mame2015 = mkLibRetroCore {
  