Hello, It seems that the silly compilation problem with hcoll_rte.c I had back in April with mpich 4.3.0 when using --with-hcoll=/opt/mellanox/hcoll configuration option is still present in 4.3.1, see: https://urldefense.us/v3/__https://lists.mpich.org/mailman/htdig/discuss/202... It seems that the following very simple patch I was told to try with 4.3.0 haven't been included in 4.3.1: --- src/mpid/common/hcoll/hcoll_rte.c 2025-04-16 12:54:24.847337975 -0400 +++ src/mpid/common/hcoll/hcoll_rte.c 2025-04-16 12:55:05.428164974 -0400 @@ -55,7 +55,7 @@ /* FIXME: The hcoll library needs to be updated to return * error codes. The progress function pointer right now * expects that the function returns void. */ - ret = hcoll_do_progress(&made_progress); + ret = hcoll_do_progress(-1, &made_progress); MPIR_Assert(ret == MPI_SUCCESS); } } So it look like this code path is not compiled very often by mpich developers or it's QA process. BTW applying the same patch fix the compilation problem, but: What does it mean for us users ? Should we still use this option ? BTW hcoll is a very cool mechanism for improving collective operations efficiency. Is this option obsolete ? Was it replaced by something else ? Thanks, Martin Audet