Hi folks, We are considering adding support for symbol visibility into MPICH. This is a standard shared library best-practice that reduces the exposed API, and leads to better performance by reducing the number of PLT branches for internal function calls. More on symbol visibility can be found here: https://www.gnu.org/software/gnulib/manual/html_node/Exported-Symbols-of-Sha.... I wanted to get the patches in front of a wider audience so folks are aware of what we are doing and can comment. You can find the current implementation here: http://git.mpich.org/mpich-dev.git/shortlog/refs/heads/visibility. Thanks to Intel for pointing out the need for this, and an initial version of the patch. We believe this will have no impact on the MPICH ABI, and will test thoroughly once the patches land in master. Let us know what you think. Ken