So, while we need not use IBM's exact fixes, we should fix it in some way -- whatever way we think is right. We can then try to propagate those fixes back to IBM.
Would it make sense to initiate a discussion with IBM about this, or is it too early? I personally feel that we should internally use MPI_Offset instead of MPI_Aint for datatypes and I/O to calculate the total size and leave the rest (parts that are broken in the MPI standard) as they currently are. Specifically, anything that returns an MPI_Aint to the user might overflow on 32-bit systems (technically even on 64-bit systems, but we are some time away for that). But in cases where the user doesn't use such functions but MPICH2 internally has to evaluate the size, it should work fine. -- Pavan -- Pavan Balaji http://www.mcs.anl.gov/~balaji