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ccompilationcudag++nvcc

Compiling CUDA code while linking a static library

I have C code main_code.c and helper_code.c. The former depends on some CUDA code cuda_code.cu and the latter on an external library mylib. For my external library mylib to work, I need to link it to my code with the -static flag:

g++ main_code.c helper_code.c -o main_code -static -L/usr/local/mylib/lib -lmylib -lmylib2

But main_code.c also depends on CUDA code- cuda_code.cu. I can link it with:

nvcc cuda_code.cu -c
g++ main_code.c -o main_code cuda_code.o -L/usr/local/cuda-10.0/lib64 -lcudart -lpthread

I want to compile my code together with the CUDA code and the external library mylib. However, linking mylib works only with the -static flag. A naive attempt would be the following but it does not work:

nvcc cuda_code.cu -c
g++ main_code.c helper_code.c -o main_code cuda_code.o -static -L/usr/local/mylib/lib -lmylib -lmylib2 -L/usr/local/cuda-10.0/lib64 -lcudart -lpthread

This gives the error:

/usr/bin/ld: cannot find -lcudart

which I'm assuming is because you cannot use the static flag while linking with CUDA (because it goes away when I remove the -static flag (in addition to also removing the mylib library linking)).

I then tried compiling helper_code.c separately and then linking it to main_code.c since it's just helper_code.c that needs mylib:

helper.o:
    g++ helper_code.c -c -static -L/usr/local/mylib/lib -lmylib -lmylib2

cuda-code.o:
    nvcc cuda_code.cu -c

main-code: helper.o cuda-code.o
    g++ main_code.c -o main_code helper_code.o cuda_code.o -L/usr/local/cuda-10.0/lib64 -lcudart -lpthread

But this also does not work. I get an undefined reference error that's referring to a function defined in mylib, meaning the linking to mylib isn't working. I can resolve that error by including the mylib library and using the -static flag but that then breaks the CUDA linking.

I can separately get the CUDA linking (to cuda_code.cu) to work or mylib linking to work but not both at the same time.

So is there a workaround to link mylib (which needs -static) while at the same time also linking my CUDA code (which does not allow -static)?

Solution

  • Following the answer linked in talonmies's comment, the following did the trick:

    g++ main_code.c -o main_code helper_code.o cuda_code.o -L/usr/local/mylib/lib -L/usr/local/cuda-10.0/lib64 -Wl,-Bstatic -lmylib -lmylib2 -Wl,-Bdynamic -lcudart