Investigate RPATH mapping for libfmpich.so
Using LD_PRELOAD for Fortran executables requires that libfmpich.so be specified in addition to libdarshan.so in the LD_PRELOAD variable.
However, if you leave out the full path to libfmpich.so it isn't clear whether the runtime linker will find the one in the RPATH of libdarshan.so (which should point to a gcc build of mpich) or whether it will find one in the RPATH of the executable (which may use a different mpich build). At runtime we need to use the libfmpich.so that matches the executable, not darshan.
We need to investigate this further and find out if there is a way to get the behavior that we want.