如何刪除opencl代碼中的CL_INVALID_PLATFORM錯誤？

Question

做使用OpenCL的簡單矩陣乘法：

// Multiply two matrices A * B = C 

#include <stdlib.h> 
#include <stdio.h> 
#include <math.h> 
#include <oclUtils.h> 

#define WA 3 
#define HA 3 
#define WB 3 
#define HB 3 
#define WC 3 
#define HC 3 

// Allocates a matrix with random float entries. 
void randomInit(float* data, int size) 
{ 
    for (int i = 0; i < size; ++i) 
    data[i] = rand()/(float)RAND_MAX; 
} 

///////////////////////////////////////////////////////// 
// Program main 
///////////////////////////////////////////////////////// 

int 
main(int argc, char** argv) 
{ 

    // set seed for rand() 
    srand(2006); 

    // 1. allocate host memory for matrices A and B 
    unsigned int size_A = WA * HA; 
    unsigned int mem_size_A = sizeof(float) * size_A; 
    float* h_A = (float*) malloc(mem_size_A); 

    unsigned int size_B = WB * HB; 
    unsigned int mem_size_B = sizeof(float) * size_B; 
    float* h_B = (float*) malloc(mem_size_B); 

    // 2. initialize host memory 
    randomInit(h_A, size_A); 
    randomInit(h_B, size_B); 

    // 3. print out A and B 
    printf("\n\nMatrix A\n"); 
    for(int i = 0; i < size_A; i++) 
    { 
     printf("%f ", h_A[i]); 
     if(((i + 1) % WA) == 0) 
     printf("\n"); 
    } 

    printf("\n\nMatrix B\n"); 
    for(int i = 0; i < size_B; i++) 
    { 
     printf("%f ", h_B[i]); 
     if(((i + 1) % WB) == 0) 
     printf("\n"); 
    } 

    // 4. allocate host memory for the result C 
    unsigned int size_C = WC * HC; 
    unsigned int mem_size_C = sizeof(float) * size_C; 
    float* h_C = (float*) malloc(mem_size_C); 

    // 5. Initialize OpenCL 
    // OpenCL specific variables 
    cl_context clGPUContext; 
    cl_command_queue clCommandQue; 
    cl_program clProgram; 
    cl_kernel clKernel; 

    size_t dataBytes; 
    size_t kernelLength; 
    cl_int errcode; 

    // OpenCL device memory for matrices 
    cl_mem d_A; 
    cl_mem d_B; 
    cl_mem d_C; 

    /*****************************************/ 
    /* Initialize OpenCL */ 
    /*****************************************/ 

    clGPUContext = clCreateContextFromType(0, 
        CL_DEVICE_TYPE_GPU, 
        NULL, NULL, &errcode); 
    shrCheckError(errcode, CL_SUCCESS); 

    // get the list of GPU devices associated 
    // with context 
    errcode = clGetContextInfo(clGPUContext, 
       CL_CONTEXT_DEVICES, 0, NULL, 
       &dataBytes); 
    cl_device_id *clDevices = (cl_device_id *) 
       malloc(dataBytes); 
    errcode |= clGetContextInfo(clGPUContext, 
       CL_CONTEXT_DEVICES, dataBytes, 
       clDevices, NULL); 
    //shrCheckError(errcode, CL_SUCCESS); 

    //Create a command-queue 
    clCommandQue = clCreateCommandQueue(clGPUContext, 
        clDevices[0], 0, &errcode); 
    //shrCheckError(errcode, CL_SUCCESS); 

    // Setup device memory 
    d_C = clCreateBuffer(clGPUContext, 
      CL_MEM_READ_WRITE, 
      mem_size_A, NULL, &errcode); 
    d_A = clCreateBuffer(clGPUContext, 
      CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, 
      mem_size_A, h_A, &errcode); 
    d_B = clCreateBuffer(clGPUContext, 
      CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, 
      mem_size_B, h_B, &errcode); 


    // 6. Load and build OpenCL kernel 
    char *clMatrixMul = oclLoadProgSource("kernel.cl", 
         "// My comment\n", 
         &kernelLength); 
    //shrCheckError(clMatrixMul != NULL, shrTRUE); 

    clProgram = clCreateProgramWithSource(clGPUContext, 
       1, (const char **)&clMatrixMul, 
       &kernelLength, &errcode); 
    //shrCheckError(errcode, CL_SUCCESS); 

    errcode = clBuildProgram(clProgram, 0, 
       NULL, NULL, NULL, NULL); 
    //shrCheckError(errcode, CL_SUCCESS); 

    clKernel = clCreateKernel(clProgram, 
       "matrixMul", &errcode); 
    //shrCheckError(errcode, CL_SUCCESS); 


    // 7. Launch OpenCL kernel 
    size_t localWorkSize[2], globalWorkSize[2]; 

    int wA = WA; 
    int wC = WC; 
    errcode = clSetKernelArg(clKernel, 0, 
       sizeof(cl_mem), (void *)&d_C); 
    errcode |= clSetKernelArg(clKernel, 1, 
       sizeof(cl_mem), (void *)&d_A); 
    errcode |= clSetKernelArg(clKernel, 2, 
       sizeof(cl_mem), (void *)&d_B); 
    errcode |= clSetKernelArg(clKernel, 3, 
       sizeof(int), (void *)&wA); 
    errcode |= clSetKernelArg(clKernel, 4, 
       sizeof(int), (void *)&wC); 
    //shrCheckError(errcode, CL_SUCCESS); 

    localWorkSize[0] = 3; 
    localWorkSize[1] = 3; 
    globalWorkSize[0] = 3; 
    globalWorkSize[1] = 3; 

    errcode = clEnqueueNDRangeKernel(clCommandQue, 
       clKernel, 2, NULL, globalWorkSize, 
       localWorkSize, 0, NULL, NULL); 
    //shrCheckError(errcode, CL_SUCCESS); 

    // 8. Retrieve result from device 
    errcode = clEnqueueReadBuffer(clCommandQue, 
       d_C, CL_TRUE, 0, mem_size_C, 
       h_C, 0, NULL, NULL); 
    //shrCheckError(errcode, CL_SUCCESS); 

    // 9. print out the results 
    printf("\n\nMatrix C (Results)\n"); 
    for(int i = 0; i < size_C; i++) 
    { 
     printf("%f ", h_C[i]); 
     if(((i + 1) % WC) == 0) 
     printf("\n"); 
    } 
    printf("\n"); 

    // 10. clean up memory 
    free(h_A); 
    free(h_B); 
    free(h_C); 

    clReleaseMemObject(d_A); 
    clReleaseMemObject(d_C); 
    clReleaseMemObject(d_B); 

    free(clDevices); 
    free(clMatrixMul); 
    clReleaseContext(clGPUContext); 
    clReleaseKernel(clKernel); 
    clReleaseProgram(clProgram); 
    clReleaseCommandQueue(clCommandQue); 

} 

在上面的代碼中，我一直在這個地方得到錯誤：

/* ** * ** * * * * ** * ** * ** * *** //初始化的OpenCL // ** * ** * ** * ** * ** * ** * * * * */ clGPUContext = clCreateContextFromType（0， CL_DEVICE_TYPE_GPU， NULL，NULL，& ERRCODE）; shrCheckError（errcode，CL_SUCCESS）;

返回錯誤代碼是-32，這意味着：CL_INVALID_PLATFORM」

我如何刪除這個錯誤

OS：Windows 7中，32位，NVIDIA GPU的GeForce 610

Answer 1

Nvidia驅動程序期望您提供一個非NULL屬性指針作爲clCreateContextFromType調用的第一個參數。

Khronos規範clCreateContextFromType如果爲屬性參數傳遞了NULL，則選擇的平臺是與實現相關的。對於Nvidia來說，選擇似乎是，如果傳遞NULL指針，則根本不會選擇任何平臺。有關更多信息，請參閱clCreateContextFromType。

在另一方面，這種行爲是在cl_khr_icd extension問題＃3，假若您是通過ICD使用OpenCL的應用一致的，並指出：

3: How will the ICD handle a NULL cl_platform_id? 

RESOLVED: The NULL platform is not supported by the ICD. 

要傳遞將屬性設置爲clCreateContextFromType，首先使用clGetPlatformIDs查詢平臺。然後構建一個具有所需平臺ID的屬性數組，並將其傳遞給clCreateContextFromType。沿着以下幾行的東西應該與C99兼容的編譯器一起工作：

// query the number of platforms 
    cl_uint numPlatforms; 
    errcode = clGetPlatformIDs(0, NULL, &numPlatforms); 
    shrCheckError(errcode, CL_SUCCESS); 

    // now get all the platform IDs 
    cl_platform_id platforms[numPlatforms]; 
    errcode = clGetPlatformIDs(numPlatforms, platforms, NULL); 
    shrCheckError(errcode, CL_SUCCESS); 

    // set platform property - we just pick the first one 
    cl_context_properties properties[] = {CL_CONTEXT_PLATFORM, (int) platforms[0], 0}; 
    clGPUContext = clCreateContextFromType(properties, CL_DEVICE_TYPE_GPU, NULL, NULL, &errcode); 
    shrCheckError(errcode, CL_SUCCESS);