Grant> gsyprf3:/usr/src/linux-2.6# ibv_pingpong libibverbs: Grant> Warning: no driver for uverbs0 Grant> What obvious, silly thing did I overlook? Where is mthca.so installed? By default libibverbs only looks in $PREFIX/lib/infiniband, but you can add any path via the OPENIB_DRIVER_PATH environment variable. - R.