External calls are not supported - CUDA

Question

Objective is to call a device function available in another file, when i compile the global kernel it shows the following error *External calls are

Answer 1

You're trying to do separate compilation, which needs some special command line options. See the NVCC manual for details, but here's how to get your example to compile. I've targeted sm_20, but you can target sm_20 or later depending on what GPU you have. Separate compilation is not possible on older devices (sm_1x).

• You don't need to declare the __device__ function as extern in your header file, but if you have any static device variables they will need to be declared as extern

• Generate relocatable code for the device by compiling as shown below (-dc is the device equivalent of -c, see the manual for more information)

  nvcc -arch=sm_20 -dc norm.cu -o norm.o -I.
  nvcc -arch=sm_20 -dc test.cu -o test.o -I.
  

• Link the device parts of the code by calling nvlink before the final host link

  nvlink -arch=sm_20 norm.o test.o -o final.o