OpenCL Kernel - 2021.1 English

The Xilinx Runtime (XRT) library supports the OpenCL™ printf() built-in function within kernels in all build configurations: software emulation, hardware emulation, and during hardware execution.

The following is an example of using printf() in the kernel, and the output when the kernel is executed with global size of 8:

__kernel __attribute__ ((reqd_work_group_size(1, 1, 1)))
void hello_world(__global int *a)
{
    int idx = get_global_id(0);

     printf("Hello world from work item %d\n", idx);
     a[idx] = idx;
}

The output is as follows:

Hello world from work item 0
Hello world from work item 1
Hello world from work item 2
Hello world from work item 3
Hello world from work item 4
Hello world from work item 5
Hello world from work item 6
Hello world from work item 7