[mpiwg-rma] MPI_Win_create on unmapped memory?

[Jeff Hammond]

If a user passes a (base,size) pair that corresponds to a range of
addresses that are not allocated and/or mapped, is that a correct MPI
program?

The only text I can find that implies that buffers passed to MPI_Win_create
have to be allocated is the following, assuming that one interprets
"existing memory" this way.

"Each process specifies a window of existing memory that it exposes to RMA
accesses by the processes in the group of comm." (MPI 3.1 11.2.1)

The Fortran-specific text is similarly suggestive, but it only says that a
user can pass a simply contiguous array, not that such a thing is required.

"In Fortran, one can pass the first element of a memory region or a whole
array, which must be ‘simply contiguous’"

Thanks,

Jeff

--
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/
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