Positive test with a custom OpenMPI easyconfig using --with-ucx:
https://gist.github.com/68eaf4245f6b4ce2899b9c2f9a2bef48

Positive with standard OpenMPI-4.0.3-gcccuda-2020a.eb:
https://gist.github.com/aa873272523739afd3d7f588ab84b6be

@lexming You can upload test reports in easyblock PRs now, using --include-easyblocks-from-pr 2230 --upload-test-report (as long as --from-pr isn't used, the test report will go into the easyblock PR)

I'm having one issue with this hard check: we sometimes need verbs at runtime for DDT, see this bug:
open-mpi/ompi#6464

The way we deal with this is having the OpenMPI module set this (in Lua code):

setenv("OMPI_MCA_btl","^openib")

so that it's possible to use --mca pml ob1 --mca btl openib if needed.

Would it still be possible to somehow force both UCX and Verbs without modifying the easyblock?

@bartoldeman these checks are under if config_opt_unused('verbs'):, so you can manually overwrite this behaviour by manually adding --with-verbs to the configopts of the easyconfig.

Test report by @boegel

Overview of tested easyconfigs (in order)

• SUCCESS OpenMPI-4.0.3-GCC-9.3.0.eb
• SUCCESS OpenMPI-3.1.1-GCC-7.3.0-2.30.eb
• SUCCESS OpenMPI-3.1.4-GCC-8.3.0.eb

Build succeeded for 3 out of 3 (3 easyconfigs in total)
generoso - Linux centos linux 8.2.2004, x86_64, Intel(R) Xeon(R) CPU E5-2667 v3 @ 3.20GHz (haswell), Python 3.6.8
See https://gist.github.com/94774804509d837ebe98e6af6464a5a9 for a full test report.