[Mpi3-rma] Urgent: Target displacement sign issue

[Jim Dinan]

Hi All,

We're down to the wire on this change.  As specified, dynamic windows 
will /not/ work reliably in MPI 3.0.  We currently see "negative" 
displacements for dynamic windows in MPICH on 32-bit platforms. 
Earlier, I suggested a change stating that the implementation will 
ignore the sign for dynamic windows.  Here's a revised proposal.

In the paragraph on page 425, line 1, add the bracketed sentence:

In the case of a window created with MPI_WIN_CREATE_DYNAMIC, the 
target_disp for all RMA functions is the address at the target; i.e., 
the effective window_base is MPI_BOTTOM and the disp_unit is one. [Thus, 
for dynamic windows, the target_disp argument to RMA communication 
operations is not restricted to non-negative values.] Users should use 
MPI_GET_ADDRESS at the target process to determine the address of a 
target memory location and communicate this address to the origin process.

  ~Jim.