We discussed this on the OMPI call yesterday, but I am not knowledgeable of the consequences of only supporting building Open MPI main and v5.x against PMIx v4.x are (vs. also supporting building Open MPI main+v5.x against PMIx v3.2.x, or even PMIx v3.x).
I think we might need to talk to the PMIx community and find out what those consequences are. Then we can decide what we'd like to do here for Open MPI main/v5.0.x. -- Jeff Squyres jsquy...@cisco.com ________________________________________ From: devel <devel-boun...@lists.open-mpi.org> on behalf of Austen W Lauria via devel <devel@lists.open-mpi.org> Sent: Tuesday, May 3, 2022 12:07 PM To: Jeff Squyres (jsquyres) via devel Cc: Austen W Lauria Subject: [OMPI devel] What PMIx version(s) does v5.0.0 and main support? There is a question as to what PMIx versions OMPI supports, specifically with respect to v5.0.0 and main. This came to our attention where a user tried to build OMPI v5 with PMIx v3.2.3, and ran into compile issues: https://github.com/open-mpi/ompi/issues/10341 This leads to some open questions: 1. Is there a need to support v3.2.3 PMIx or lower with v5.0.0? - If so, these compile errors need to get stamped out. Sessions in v5.0.0 would also be impacted, and will need to be disabled in this case since it relies on PMIx v4 features not available in the v3 series. It would also be good to either add an MTT build and/or a CI test to make sure this does not break in the future. 2. Could/should OMPI compiled with a v4 PMIx work with SLURM compiled with a v3.2 PMIx? - There are some cross-version-compatibility features with PMIx, so it may be possible. Finally, the PMIx version(s) as well as other required OMPI dependencies need to be documented. There is an open issue here to track that here: https://github.com/open-mpi/ompi/issues/10345. Thanks
