How do I FFI a CUDA application on Haskell? - haskell

Question

I've ported a Haskell application to CUDA in order to accelerate it. Now, I have a .cu file which I want to use from Haskell as an API. I've managed to FFI C files easily following the tutorials, but I'm not sure how this applies to CUDA/nvcc. How do I do it?
For completion, this is what I get trying to treat the .cu as a normal .c file:
vh:CUDA apple1$ nvcc hello.cu -c -o hello.o
vh:CUDA apple1$ ghc test.hs -o test hello.o
Linking test ...
Undefined symbols for architecture x86_64:
"___cudaRegisterFatBinary", referenced from:
__sti____cudaRegisterAll_40_tmpxft_00002168_00000000_7_hello_cpp1_ii_f33df8d2() in hello.o
"___cudaRegisterFunction", referenced from:
__nv_cudaEntityRegisterCallback(void**) in hello.o
"___cudaUnregisterFatBinary", referenced from:
__cudaUnregisterBinaryUtil() in hello.o
"_cudaConfigureCall", referenced from:
render(Renderer_*) in hello.o
"_cudaFree", referenced from:
renderer_free(Renderer_*) in hello.o
"_cudaLaunch", referenced from:
cudaError cudaLaunch<char>(char*) in hello.o
"_cudaMalloc", referenced from:
renderer_init(Renderer_*, float, float, float, float, float) in hello.o
"_cudaMemcpy", referenced from:
renderer_init(Renderer_*, float, float, float, float, float) in hello.o
render(Renderer_*) in hello.o
"_cudaSetupArgument", referenced from:
__device_stub__Z4walk6float3PiS_S_S_S_S0_(float3&, int*, float3&, float3&, float3&, float3&, int*) in hello.o
"_hello", referenced from:
_r3yw_info in test.o
_c3Ib_info in test.o
_c3Il_info in test.o
(maybe you meant: _Main_hello_closure, _Main_hello_info )
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
And that is my Haskell file:
{-# LANGUAGE ForeignFunctionInterface #-}
module Main where
import Foreign.C
import Foreign.Ptr (Ptr,nullPtr)
foreign import ccall "hello" hello :: IO ()
main = hello

Answer 1

I managed to solve it by adding extern "C" to all functions on hello.cu:
-- hello.cu
extern "C"
void hello();
Compiling the CUDA file with:
nvcc -c hello.cu
And the Haskell file with:
ghc --make test.hs -o test hello.o -L/usr/local/cuda/lib -optl-lcudart