How to let cmake find CUDA

Question

I am trying to build this project, which has CUDA as a dependency. But the cmake script cannot find the CUDA installation on the system:

cls ~/workspace/gpucluster/cluster/build $ cmake .. -- The C compiler identification is GNU 4.7.1 -- The CXX compiler identification is GNU 4.7.1 -- Check for working C compiler: /usr/bin/gcc -- Check for working C compiler: /usr/bin/gcc -- works -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working CXX compiler: /usr/bin/c++ -- Check for working CXX compiler: /usr/bin/c++ -- works -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done CMake Error at /usr/share/cmake/Modules/FindCUDA.cmake:488 (message):   Specify CUDA_TOOLKIT_ROOT_DIR Call Stack (most recent call first):   CMakeLists.txt:20 (find_package) 

-- Configuring incomplete, errors occurred!

I've tried adding it as an environment variable to .bashrc, to no effect:

export CUDA_TOOLKIT_ROOT_DIR=/usr/local/cuda-5.5 

How do I Specify CUDA_TOOLKIT_ROOT_DIR correctly?

Answer 1

cmake mentioned CUDA_TOOLKIT_ROOT_DIR as cmake variable, not environment one. That's why it does not work when you put it into .bashrc. If you look into FindCUDA.cmake it clearly says that:

The script will prompt the user to specify CUDA_TOOLKIT_ROOT_DIR if the prefix cannot be determined by the location of nvcc in the system path and REQUIRED is specified to find_package(). To use a different installed version of the toolkit set the environment variable CUDA_BIN_PATH before running cmake (e.g. CUDA_BIN_PATH=/usr/local/cuda1.0 instead of the default /usr/local/cuda) or set CUDA_TOOLKIT_ROOT_DIR after configuring. If you change the value of CUDA_TOOLKIT_ROOT_DIR, various components that depend on the path will be relocated.

So put CUDA_BIN_PATH into .bashrc or specify CUDA_TOOLKIT_ROOT_DIR to cmake:

cmake -D CUDA_TOOLKIT_ROOT_DIR=/usr/local/cuda-5.5 ..