Is it valid in _MPICH_ to make calls to PMI before MPI is initialized? I am interested in PMI_Init, PMI_Get_size and PMI_Get_rank. The motivating use case is to initialize e.g. half my ranks with MPI_THREAD_FUNNELED and the other half with MPI_THREAD_MULTIPLE but not use MPMD launching. I have two reasons for wanting to do it this way. First, it is otherwise unnecessary to use MPMD since I can branch at the top of my code and meet the requirements of FUNNELED and MULTIPLE. Second, I might be interested in running my code on a supercomputer with an MPICH-based MPI implementation that does not support MPMD launching in an unrestricted manner. If MPICH can handle this, then I will worry about whether or not the aforementioned supercomputer can. It is my assumption that, if MPICH cannot handle this, then the MPICH derivative in question cannot either. Thanks, Jeff -- Jeff Hammond [email protected] http://jeffhammond.github.io/