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EnDoerner
12-19-2012, 10:54 AM
I was studing this example of clCreateSubBuffer from the book "OpenCL in Action" but when the program executes clCreateSubBuffer it gives the error code -37.

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>

#ifdef MAC
#include <OpenCL/cl.h>
#else
#include <CL/cl.h>
#endif

/* Find a GPU or CPU associated with the first available platform */
cl_device_id create_device() {

cl_platform_id platform;
cl_device_id dev;
int err;

/* Identify a platform */
err = clGetPlatformIDs(1, &platform, NULL);
if(err < 0) {
perror("Couldn't identify a platform");
exit(1);
}

/* Access a device */
err = clGetDeviceIDs(platform, CL_DEVICE_TYPE_GPU, 1, &dev, NULL);
if(err == CL_DEVICE_NOT_FOUND) {
err = clGetDeviceIDs(platform, CL_DEVICE_TYPE_CPU, 1, &dev, NULL);
}
if(err < 0) {
perror("Couldn't access any devices");
exit(1);
}

return dev;
}

int main() {

/* Host/device data structures */
cl_device_id device;
cl_context context;
cl_int err;

/* Data and buffers */
float main_data[100];
cl_mem main_buffer, sub_buffer;
void *main_buffer_mem = NULL, *sub_buffer_mem = NULL;
size_t main_buffer_size, sub_buffer_size;
cl_buffer_region region;

/* Create device and context */
device = create_device();
context = clCreateContext(NULL, 1, &device, NULL, NULL, &err);
if(err < 0) {
perror("Couldn't create a context");
exit(1);
}

/* Create a buffer to hold 100 floating-point values */
main_buffer = clCreateBuffer(context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, sizeof(main_data), main_data, &err);
if(err < 0) {
perror("Couldn't create a buffer");
exit(1);
}

/* Create a sub-buffer containing values 30-49 */
region.origin = 30*sizeof(float);
region.size = 20*sizeof(float);
sub_buffer = clCreateSubBuffer(main_buffer, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR , CL_BUFFER_CREATE_TYPE_REGION, &region, &err);
if(err < 0) {
perror("Couldn't create a sub-buffer");
exit(1);
}

/* Obtain size information about the buffers */
clGetMemObjectInfo(main_buffer, CL_MEM_SIZE,
sizeof(main_buffer_size), &main_buffer_size, NULL);
clGetMemObjectInfo(sub_buffer, CL_MEM_SIZE,
sizeof(sub_buffer_size), &sub_buffer_size, NULL);
printf("Main buffer size: %lu\n", main_buffer_size);
printf("Sub-buffer size: %lu\n", sub_buffer_size);

/* Obtain the host pointers */
clGetMemObjectInfo(main_buffer, CL_MEM_HOST_PTR, sizeof(main_buffer_mem),
&main_buffer_mem, NULL);
clGetMemObjectInfo(sub_buffer, CL_MEM_HOST_PTR, sizeof(sub_buffer_mem),
&sub_buffer_mem, NULL);
printf("Main buffer memory address: %p\n", main_buffer_mem);
printf("Sub-buffer memory address: %p\n", sub_buffer_mem);

/* Print the address of the main data */
printf("Main array address: %p\n", main_data);

/* Deallocate resources */
clReleaseMemObject(main_buffer);
clReleaseMemObject(sub_buffer);
clReleaseContext(context);


return 0;
}

Well, if someone has an idea of what is bad on this example please let me know. Unfortunately I have not been able to found more information on the author's webpage or through google... thanks!

utnapishtim
12-20-2012, 07:21 AM
From the OpenCL Specification document about clCreateSubBuffer:


The CL_MEM_USE_HOST_PTR, CL_MEM_ALLOC_HOST_PTR and CL_MEM_COPY_HOST_PTR values cannot be specified in flags but are inherited from the corresponding memory access qualifiers associated with buffer.