>> By default, the code is disable and has to be configured into the library.
>> --with-cuda(=DIR) Build cuda support, optionally adding DIR/include,
>> DIR/lib, and DIR/lib64
>> --with-cuda-libdir=DIR Search for cuda libraries in DIR
> My $0.02: cuda shouldn't be disabled by default (and only enabled if you --with-cuda). If configure finds all the Right cuda magic, then cuda support should be enabled by default. Just like all other optional support libraries that OMPI uses.
Actually I'm not sure that it is good idea to enable CUDA by default, since it disables zero-copy protocol, that is critical for good performance.