Don't know if there are implementations where the MPI handle is not an integer of size of an address. Would your suggestion work if it were? Cheers, Craig On Feb 19, 2008, at 9:32 AM, Lionel, Steve wrote:

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Jeff and I tried to make this work out in our paper but thought there might be problems interfacing with exiting MPI implementations. However, I agree this would be a better approach if it can be made to work with MPI implementations that work with both integers and pointers to structs. I'll think some more about how to use your approach, perhaps you could add you brain power to it as well.

I think this should be the main topic for conversation in our telecon this week. Agree?

I will admit that I am not steeped in MPI to anywhere near the degree I am in Fortran. If you're saying that there are MPI implementations where the handle is an integer that is NOT also the size of an address, then that would be tricky and would have to be handled as an implementation-dependent named constant giving the proper kind value based on the equivalent C type. (An irritant is that Fortran KIND values are implementation-dependent, so what may be kind 4 for one compiler is kind 3 for another. But using the values in ISO_C_BINDING would be the way around that.)

I'll be glad to help as best I can. I agree that this is a fundamental issue that needs to be resolved before you can get much further. I would argue for an opaque type regardless - you can change what's inside it on a per-implementation basis.

I have not participated in the con calls before, so please point me to the details when they become available.

Steve Lionel Developer Products Division Intel Corporation Nashua, NH

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