error to string?

Is it possible to get a human-readable message from en error code, similar to what perror() does?

You would have to build your own table/function to do that with the provided interface. It wouldn’t be hard, but it isn’t supplied at the moment.

Another approach is to use the context callback function. If the implementation is helpful it should provide more detailed error information via that method. My experience with the Snow Leopard implementation is that you get all sorts of helpful advice from their context callback function.

Feel free to use this as the basis of something, it’s Objective C, but could be normal C with a little tweaking:

+ (NSString *) descriptionOfError:(cl_int) err {
    switch (err) {
        case CL_SUCCESS:                            return @"Success!";
        case CL_DEVICE_NOT_FOUND:                   return @"Device not found.";
        case CL_DEVICE_NOT_AVAILABLE:               return @"Device not available";
        case CL_COMPILER_NOT_AVAILABLE:             return @"Compiler not available";
        case CL_MEM_OBJECT_ALLOCATION_FAILURE:      return @"Memory object allocation failure";
        case CL_OUT_OF_RESOURCES:                   return @"Out of resources";
        case CL_OUT_OF_HOST_MEMORY:                 return @"Out of host memory";
        case CL_PROFILING_INFO_NOT_AVAILABLE:       return @"Profiling information not available";
        case CL_MEM_COPY_OVERLAP:                   return @"Memory copy overlap";
        case CL_IMAGE_FORMAT_MISMATCH:              return @"Image format mismatch";
        case CL_IMAGE_FORMAT_NOT_SUPPORTED:         return @"Image format not supported";
        case CL_BUILD_PROGRAM_FAILURE:              return @"Program build failure";
        case CL_MAP_FAILURE:                        return @"Map failure";
        case CL_INVALID_VALUE:                      return @"Invalid value";
        case CL_INVALID_DEVICE_TYPE:                return @"Invalid device type";
        case CL_INVALID_PLATFORM:                   return @"Invalid platform";
        case CL_INVALID_DEVICE:                     return @"Invalid device";
        case CL_INVALID_CONTEXT:                    return @"Invalid context";
        case CL_INVALID_QUEUE_PROPERTIES:           return @"Invalid queue properties";
        case CL_INVALID_COMMAND_QUEUE:              return @"Invalid command queue";
        case CL_INVALID_HOST_PTR:                   return @"Invalid host pointer";
        case CL_INVALID_MEM_OBJECT:                 return @"Invalid memory object";
        case CL_INVALID_IMAGE_FORMAT_DESCRIPTOR:    return @"Invalid image format descriptor";
        case CL_INVALID_IMAGE_SIZE:                 return @"Invalid image size";
        case CL_INVALID_SAMPLER:                    return @"Invalid sampler";
        case CL_INVALID_BINARY:                     return @"Invalid binary";
        case CL_INVALID_BUILD_OPTIONS:              return @"Invalid build options";
        case CL_INVALID_PROGRAM:                    return @"Invalid program";
        case CL_INVALID_PROGRAM_EXECUTABLE:         return @"Invalid program executable";
        case CL_INVALID_KERNEL_NAME:                return @"Invalid kernel name";
        case CL_INVALID_KERNEL_DEFINITION:          return @"Invalid kernel definition";
        case CL_INVALID_KERNEL:                     return @"Invalid kernel";
        case CL_INVALID_ARG_INDEX:                  return @"Invalid argument index";
        case CL_INVALID_ARG_VALUE:                  return @"Invalid argument value";
        case CL_INVALID_ARG_SIZE:                   return @"Invalid argument size";
        case CL_INVALID_KERNEL_ARGS:                return @"Invalid kernel arguments";
        case CL_INVALID_WORK_DIMENSION:             return @"Invalid work dimension";
        case CL_INVALID_WORK_GROUP_SIZE:            return @"Invalid work group size";
        case CL_INVALID_WORK_ITEM_SIZE:             return @"Invalid work item size";
        case CL_INVALID_GLOBAL_OFFSET:              return @"Invalid global offset";
        case CL_INVALID_EVENT_WAIT_LIST:            return @"Invalid event wait list";
        case CL_INVALID_EVENT:                      return @"Invalid event";
        case CL_INVALID_OPERATION:                  return @"Invalid operation";
        case CL_INVALID_GL_OBJECT:                  return @"Invalid OpenGL object";
        case CL_INVALID_BUFFER_SIZE:                return @"Invalid buffer size";
        case CL_INVALID_MIP_LEVEL:                  return @"Invalid mip-map level";
        default: return @"Unknown";

If the platform implements a context callback function you should be able to get more detailed error information from that. Apple provides several in their header files that you can just put in, or you can set the CL_LOG_ERRORS=stdout environment variable and get detailed error information printed out to the console. I’m afraid I don’t know what other vendors do.

Thanks, this is just what I wanted.

I also added a context callback function that simply prints the given ‘errinfo’ string, but it is also given a pointer to something that the specification calls ‘private_info’. According to the specification, this is a pointer to binary data that is returned by the OpenCL implementation. However, I have not been able to find any description of the contents of this data. I assume it is implementation specific, but have not been able to find anything about it in the documents I’ve got with the NVIDIA OpenCL SDK.