All, I'm sort of new to MPICH and I'm encountering one call that works with Open MPI but not MPICH. As such, I'm wondering if I built MPICH incorrectly or incompletely (always easy to miss a configure flag!). To wit, I have a code like: program main use mpi use iso_fortran_env, only: INT64 use iso_c_binding, only: C_PTR integer(kind=INT64) :: sz type (c_ptr) :: ptr call MPI_Alloc_mem(sz, MPI_INFO_NULL, ptr, ierror) end program main If I compile with GCC 12.1 + Open MPI 4.1.3, all is well: $ mpifort --showme:version mpifort: Open MPI 4.1.3 (Language: Fortran) mathomp4@discover23 ~/MPITests/CPtr master ?25 $ mpifort support_for_mpi_alloc_mem_cptr.F90 mathomp4@discover23 ~/MPITests/CPtr master ?25 $ echo $? 0 I'll also say Intel MPI builds this code as well. But with MPICH 4.1.2 I just built: $ mpifort support_for_mpi_alloc_mem_cptr.F90 support_for_mpi_alloc_mem_cptr.F90:9:53: 9 | call MPI_Alloc_mem(sz, MPI_INFO_NULL, ptr, ierror) | 1 Error: Type mismatch in argument 'baseptr' at (1); passed TYPE(c_ptr) to INTEGER(8) Now, my configure lines to Open MPI and MPICH are pretty boring, so the resulting mpiforts are as well: $ mpifort -show gfortran -I/discover/swdev/gmao_SIteam/MPI/openmpi/4.1.3/gcc-12.1.0/include -pthread -I/discover/swdev/gmao_SIteam/MPI/openmpi/4.1.3/gcc-12.1.0/lib -L/discover/swdev/gmao_SIteam/MPI/openmpi/4.1.3/gcc-12.1.0/lib -lmpi_usempif08 -lmpi_usempi_ignore_tkr -lmpi_mpifh -lmpi $ mpifort -show gfortran -I/discover/swdev/gmao_SIteam/MPI/mpich/4.1.2/gcc-12.1.0/include -I/discover/swdev/gmao_SIteam/MPI/mpich/4.1.2/gcc-12.1.0/include -L/discover/swdev/gmao_SIteam/MPI/mpich/4.1.2/gcc-12.1.0/lib -lmpifort -Wl,-rpath -Wl,/discover/swdev/gmao_SIteam/MPI/mpich/4.1.2/gcc-12.1.0/lib -Wl,--enable-new-dtags -lmpi But I see Open MPI has that "mpi_usempi_ignore_tkr", is it possible that's what is doing it? Perhaps we just need to recode the code (using transfer, etc?) Thanks for any help, Matt -- Matt Thompson, SSAI, Sr Scientific Programmer/Analyst NASA GSFC, Global Modeling and Assimilation Office Code 610.1, 8800 Greenbelt Rd, Greenbelt, MD 20771 Phone: 301-614-6712 Fax: 301-614-6246 http://science.gsfc.nasa.gov/sed/bio/matthew.thompson