Reply To: Multiple GPU compiler error: cannot find -lmpi_cxx: No such file or director
If you want to use nvcc directly for the entire compilation you quite likely will need to manually prescribe all MPI flags. Those are usually set by the mpicxx wrapper, you can get them for your environment using mpicxx --showme:compile resp. --showme:link. This is what is suggested in the config/gpu_openmpi.mk config (which I assume you started with?)
I would recommend to use the config/gpu_openmpi_mixed.mk as a starting point. You can compare config/gpu_horeka_nvidiahpc_mixed.mk to see how this looks like for a real world cluster.
I assume you already have selected the CUDA and MPI modules (with CUDA-awareness compiled in) for your cluster? If so I should be able to guide you to a working config given the output of mpicxx --showme and (optionally) the path to the CUDA module.
You may also be lucky and be able to use config/gpu_openmpi_mixed.mk basically unmodified if the cluster modules are set up well. This recently happened to me on the Karolina cluster at IT4I (unfortunately this is also the only cluster I encountered where all required modules were set up fully, removing the need for any manual flag twiddling).