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Creating DLL from CUDA using nvcc

Tags:

cuda

dll

nvcc

I want to create a .dll from a CUDA code (kernel.cu) in order to use this library from an external C program. After some attempts I just left a simple C function in .cu file. Code follows:

kernel.cu

#include <stdio.h>
#include "kernel.h"

void hello(const char *s) {
        printf("Hello %s\n", s);
}/*

kernel.h

#ifndef KERNEL_H
#define KERNEL_H

#include "cuda_runtime.h"
#include "device_launch_parameters.h"

#ifdef __cplusplus
extern "C" {
#endif

void __declspec(dllexport) hello(const char *s);

#ifdef __cplusplus
}
#endif

#endif  // KERNEL_H

I tried to first generate a kernel.o object with nvcc and after i used g++ for creating DLL as following:

nvcc -c kernel.cu -o kernel.o
g++ -shared -o kernel.dll kernel.o -L"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v5.0\lib\x64" -lcudart

It works fine and generates kernel.dll. To test DLL file I wrote this simple program main.c:

#include <stdio.h>

#ifdef __cplusplus
extern "C" {
#endif

void __declspec ( dllimport ) hello(const char *s);

#ifdef __cplusplus
}
#endif

int main(void) {
        hello("World");
        return 0;
}

compiled with:

g++ -o app.exe main.c -I"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v5.0\include" -L. -lkernel

Result is a memory access error when execution starts.

Nevertheless, if I rename .cu file in .c (as it is just C code), using the same commands, it does work. nvcc's output changes, as far as I know because it uses default C compiler instead of CUDA one.

What do you think, is it a problem related with nvcc? Or am I making any mistake?

EDIT: I forgot some info which may be important. Warnings appear in the first call to g++ (when dll is created) and they are different depending on whether .cu .c or .cpp.

.cu

Warning: .drectve `/FAILIFMISMATCH:"_MSC_VER=1600" /FAILIFMISMATCH:"_ITERATOR_DEBUG_LEVEL=0" 
/DEFAULTLIB:"libcpmt" /DEFAULTLIB:"LIBCMT" /DEFAULTLIB:"OLDNAMES" /EXPORT:hello ' unrecognized

and it doesn't work.

.cpp and .c

Warning: .drectve `/DEFAULTLIB:"LIBCMT" /DEFAULTLIB:"OLDNAMES" /EXPORT:hello ' unrecognized

and it works.

like image 283
BobCormorano Avatar asked May 07 '13 16:05

BobCormorano


Video Answer


2 Answers

Solved. I still don't know why happened (maybe it is because of not using official compiler like Robert Crovella said), but replacing the two commands for making a DLL by this one works:

nvcc -o kernel.dll --shared kernel.cu

Note the double dash (nvcc works this way), and the fact of making it directly instead of creating first .o and then making DLL from the object.

like image 110
BobCormorano Avatar answered Oct 10 '22 23:10

BobCormorano


In visual studio you can also make it compile into a .dll instead of a .obj file by navigating through the options:

DEBUG -> -Project name- Properties -> Configuration properties -> Configuration Type

Change the option from Application(.exe) to Dynamic Library(.dll)

You can find the dll after compiling in the DEBUG folder or RELEASE folder

like image 38
Jack Avatar answered Oct 10 '22 21:10

Jack