At times developers want to expose non-standard, optional interfaces to users. These interfaces may represent MPI interfaces to be presented to the MPI Forum for standardization. This page describes how a developer would go about introducing a new interface to an Open MPI branch.

For non-standard interfaces, it is strongly suggested that functions are prefixed with OMPI_ or MPIX_ instead of MPI_

branch/ompi/include/mpi.h branch/ompi/include/mpi-ext.h <auto-generated by autogen.sh and configure> <MPI standard interfaces> branch/ompi/mpi/c/ /mpi/cxx/ /mpi/f77/ /mpi/f90/ <OMPI extension interfaces> branch/ompi/mpiext/ /mpiext/example/ /mpiext/example/mpiext_example_c.h /mpiext/example/configure.m4 /mpiext/example/configure.params /mpiext/example/Makefile.am /mpiext/example/c/ /mpiext/example/c/progress.c 

autogen.sh gathers a list of available extensions in branch/ompi/mpiext. configure then chooses the headers from the enabled extensions and includes them in branch/ompi/include/mpi-ext.h

To create a new extension copy the example directory to whatever you want to identify your extension as (e.g., magic).

$ cd ompi/mpiext/ $ cp -R example magic

Edit all of the files as needed.

In order to build your extension you must explicitly enable it at configure time:

$ ./configure --enable-mpi-ext=magic

If you have more than one extension that you wish to build you can pass them as comma separated values to this configure option:

$ ./configure --enable-mpi-ext=magic,example

Extensions are built by default so nothing is needed on the configure line. However, if you want to disable building extensions:

$ ./configure --disable-mpi-ext

Headers for the extensions will be installed into:

$prefix/include/openmpi/ompi/mpiext/example/mpiext_example_c.h 

However programs need only include the base header file, which is linked in properly by the wrapper compilers:

#include <mpi-ext.h>