Dear all, Thank you for all responses. There is another problem using -fdefault-integer-8. I am using 1.6..
For the i8: configure:44650: checking for the value of MPI_STATUS_SIZE configure:44674: result: 3 Fortran INTEGERs configure:44866: checking if Fortran compiler works configure:44895: /usr/bin/gfortran44 -o conftest -m64 -g -fPIC -fdefault-integer-8 -fexceptions conftest.f >&5 configure:44895: $? = 0 MPI_STATUS_SIZE 3 For the i4: configure:44650: checking for the value of MPI_STATUS_SIZE configure:44674: result: 6 Fortran INTEGERs configure:44866: checking if Fortran compiler works configure:44895: gfortran -o conftest -m64 -g -fPIC -fexceptions conftest.f >&5 MPI_STATUS_SIZE 6 For i8, I found out later in pstatus_c2f.c for( i = 0; i < (int)(sizeof(MPI_Status) / sizeof(int)); i++ ) f_status[i] = OMPI_INT_2_FINT(c_ints[i]); It will try to write 6 integers to f_status and hence out of array bound. We need to change the configure to set MPI_STATUS_SIZE right in this case. Thanks. Regards, William