I am trying to create an OpenCL context on the platform which is containing my graphics card. But when I call clCreateContextFromType() a SEGFAULT is thrown.
int main(int argc, char** argv)
{
/*
...
*/
cl_platform_id* someValidPlatformId;
//creating heap space using malloc to store all platform ids
getCLPlatforms(someValidPlatformId);
//error handling for getCLPLatforms()
//OCLPlatform(cl_platform_id platform)
OCLPLatform platform = OCLPlatform(someValidPlatformId[0]);
//OCLContext::OCL_GPU_DEVICE == CL_DEVICE_TYPE_GPU
OCLContext context = OCLContext(platform,OCLContext::OCL_GPU_DEVICE);
/*
...
*/
}
cl_platform_id* getCLPlatforms(cl_platform_id* platforms)
{
cl_int errNum;
cl_uint numPlatforms;
numPlatforms = (cl_uint) getCLPlatformsCount(); //returns the platform count
//using clGetPlatformIDs()
//as described in the Khronos API
if(numPlatforms == 0)
return NULL;
errNum = clGetPlatformIDs(numPlatforms,platforms,NULL);
if(errNum != CL_SUCCESS)
return NULL;
return platforms;
}
OCLContext::OCLContext(OCLPlatform platform,unsigned int type)
{
this->initialize(platform,type);
}
void OCLContext::initialize(OCLPlatform platform,unsigned int type)
{
cl_int errNum;
cl_context_properties contextProperties[] =
{
CL_CONTEXT_PLATFORM,
(cl_context_properties)platform.getPlatformId(),
0
};
cout << "a" << endl;std::flush(cout);
this->context = clCreateContextFromType(contextProperties,
(cl_device_type)type,
&pfn_notify,
NULL,&errNum);
if(errNum != CL_SUCCESS)
throw OCLContextException();
cout << "b" << endl;std::flush(cout);
/*
...
*/
}
The given type is CL_DEVICE_TYPE_GPU and also the platform contained by the cl_context_properties array is valid.
To debug the error I implemented the following pfn_notify() function described by the Khronos API:
static void pfn_notify(const char* errinfo,
const void* private_info,
size_t cb, void* user_data)
{
fprintf(stderr, "OpenCL Error (via pfn_notify): %s\n", errinfo);
flush(cout);
}
Here is the ouput schown by the shell:
$ ./OpenCLFramework.exe
a
Segmentation fault
The machine i am working with has the following properties:
It would be great if somebody knew an answer to this problem.
The problem seems to be solved now.
Injecting the a valid cl_platform_id throught gdb solved the SEGFAULT. So I digged a little bit deeper and the issue for the error was that I saved the value as a standard primitive. When I called a function with this value casted to cl_platform_id some functions failed handling that. So it looks like it is a mingling of types what lead to this failure.
Now I save the value as cl_platform_id and cast it to an primitive when needed and not vice versa.
I thank you for your answers and apologize for the long radio silence for my part.