Bug#1120695: openmpi-bin: Unable to find reachable pairing between local and remote interfaces

[Santiago Vila]

On Sat, Nov 15, 2025 at 01:27:24AM +0100, José Luis García Pallero wrote:
> The definition of
> 
> export OMPI_MCA_btl_tcp_if_include=lo
> 
> makes dissapear the warning. What does it mean?

It tells OpenMPI to only use the loopback interface (lo) for TCP
communication. In this way, MPI processes can only communicate with
each other on the same machine, not across a network. I assume you
have a single machine here, so the above variable will still allow you
to use OpenMPI normally.

[ Can we close this bug? The message you see is just a warning, it does
not affect normal operation ]

Thanks.