coll MCA variables READONLY scope prevents their use via MPI_T tools interface

[burlen]

Background information

What version of Open MPI are you using? (e.g., v4.1.6, v5.0.1, git branch name and hash, etc.)

git main afc970c Oct 29 2024

Describe how Open MPI was installed (e.g., from a source/distribution tarball, from a git clone, from an operating system distribution package, etc.)

compiled from source

If you are building/installing from a git clone, please copy-n-paste the output from git submodule status.

e32e017 3rd-party/openpmix (v1.1.3-4036-ge32e0179)
0f0a90006cbc880d499b2356d6076e785e7868ba 3rd-party/prrte (psrvr-v2.0.0rc1-4819-g0f0a90006c)
dfff67569fb72dbf8d73a1dcf74d091dad93f71b config/oac (heads/main)

Please describe the system on which you are running

Ubuntu 22.04
Dual Intel Xeon
InfiniBand NDR 400

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Details of the problem

Several of the coll component's MCA variables are restrictively scoped as MCA_BASE_VAR_SCOPE_READONLY. A variable scoped READONLY can be set on the command line but not with the MPI_T tools interface. A change to MCA_BASE_VAR_SCOPE_ALL would enable these to be set by the MPI_T tools interface.