one device, no cpu and no context

OpenCL
1

Hi there,

I tried to use OpenCL on my 32-bit Ubuntu Lucid Lynx with a nVidia Quadro NVS 140M. The “deviceQuery” from “NVIDIA_GPU_Computing_SDK/C/bin/linux/release” tells me:


./deviceQuery Starting...

 CUDA Device Query (Runtime API) version (CUDART static linking)

There is 1 device supporting CUDA

Device 0: "Quadro NVS 140M"
  CUDA Driver Version:                           3.20
  CUDA Runtime Version:                          3.20
  CUDA Capability Major/Minor version number:    1.1
  Total amount of global memory:                 133890048 bytes
  Multiprocessors x Cores/MP = Cores:            2 (MP) x 8 (Cores/MP) = 16 (Cores)
  Total amount of constant memory:               65536 bytes
  Total amount of shared memory per block:       16384 bytes
  Total number of registers available per block: 8192
  Warp size:                                     32
  Maximum number of threads per block:           512
  Maximum sizes of each dimension of a block:    512 x 512 x 64
  Maximum sizes of each dimension of a grid:     65535 x 65535 x 1
  Maximum memory pitch:                          2147483647 bytes
  Texture alignment:                             256 bytes
  Clock rate:                                    0.80 GHz
  Concurrent copy and execution:                 Yes
  Run time limit on kernels:                     No
  Integrated:                                    No
  Support host page-locked memory mapping:       Yes
  Compute mode:                                  Default (multiple host threads can use this device simultaneously)
  Concurrent kernel execution:                   No
  Device has ECC support enabled:                No
  Device is using TCC driver mode:               No

deviceQuery, CUDA Driver = CUDART, CUDA Driver Version = 3.20, CUDA Runtime Version = 3.20, NumDevs = 1, Device = Quadro NVS 140M


PASSED

Press <Enter> to Quit...
-----------------------------------------------------------

So i assumed that my installation seems to work. But then I tested some C-code:


#include <stdio.h>
#include <stdlib.h>
#include <CL/cl.h>
int main (int argc, const char * argv[]) 
{
  cl_platform_id pId;
  cl_uint pNum;
  cl_int err = 0;
  cl_context context = NULL;
  cl_device_id device = NULL;
  clGetPlatformIDs(1, &pId, &pNum);

  printf("number of platforms: %i

", pNum); /*<-- allways 1*/
  err = clGetDeviceIDs(pId, CL_DEVICE_TYPE_ALL, 1, &device, NULL);
  if (err != CL_SUCCESS) 
  {
   printf("Quit!
");
   if(err == CL_INVALID_PLATFORM) 
    printf("invalid platform
");
   if(err == CL_INVALID_DEVICE_TYPE) 
    printf("invalid devicetype
");
   if(err == CL_INVALID_VALUE) 
    printf("error: device_type or num_devices
");
   if(err == CL_DEVICE_NOT_FOUND) 
    printf("no matching device_type found
");
   return 1;
  }
  context = clCreateContextFromType(0, CL_DEVICE_TYPE_GPU, NULL, NULL, NULL);
  if(context == NULL) 
  {
   printf("Invalid context
");/*<----!!!!*/
   return 2;
  }
}

But there’s never a context given back. I also tried this code without X running just by using the terminal.
This is how i compile it:


gcc main.c -I /path/to/Cuda/NVIDIA_GPU_Computing_SDK/OpenCL/common/inc/ -o main -lOpenCL

Since I am a total beginner I have no idea what the mistake could be. Any ideas?

2

The first argument to clCreateContextFromType() is a list of properties and that list should include a platform ID. You are passing NULL.

Try something like this:


cl_context_properties properties[3] = {CL_CONTEXT_PLATFORM, pId, 0 /* This zero indicates the end of the list */};

context = clCreateContextFromType(&properties[0], CL_DEVICE_TYPE_GPU, NULL, NULL, NULL);