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ndv
Journeyman III

executeNDRangeKernel crashes with segfault under certain circumstances

On Catalyst 14.12, the executeNDRangeKernel crashes with Segmentation fault, if all three conditions are met:

1. The kernel is run on GPU (Radeon R9 290x);

2. The kernel uses printf function;

3. The kernel is built from binary.

The test source is attached and displayed here:

#define __CL_ENABLE_EXCEPTIONS

#include <CL/cl.hpp>

#include <string>

#include <algorithm>

#include <iostream>

using namespace cl;

int main()

{

    std::vector<Platform> platformList;

    Platform::get(&platformList);

    cl_context_properties cprops[] = {

        CL_CONTEXT_PLATFORM,

        (cl_context_properties)(platformList[0])(),

        0};

    Context context(CL_DEVICE_TYPE_GPU, cprops);

    std::vector<Device> devices;

    devices = context.getInfo<CL_CONTEXT_DEVICES>();

   

    if (devices.size() == 0) {

        std::cerr << "No GPU devices found\n";

        exit(-1);

    }

   

    devices.erase(devices.begin()+1, devices.end()); // pick the first device

//    std::string source = "kernel void test() { }\n"; // this is OK

    std::string source = "kernel void test() { printf(\"Hello world %d\\n\",0);}\n";

    Program program(context, source);

    program.build(devices, "");

    std::vector<::size_t> sizes = program.getInfo<CL_PROGRAM_BINARY_SIZES>();

    std::vector<char *> binaries = program.getInfo<CL_PROGRAM_BINARIES>();

   

    Program::Binaries binaries1;

    binaries1.push_back(std::pair<void*,::size_t>(binaries[0], sizes[0]));

    Program program1(context, devices, binaries1);

    program1.build(devices,"");

   

    Kernel kernel(program1, "test"); // OK when using 'program' instead of 'program1'

   

    CommandQueue queue(context, devices[0], CL_QUEUE_PROFILING_ENABLE);

    Event event;

    queue.enqueueNDRangeKernel(kernel, NullRange, NDRange(1,1,1), NDRange(1,1,1), NULL, &event);

    event.wait();

}

Linux 64 bit. This was working fine on Catalyst 14.9.

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2 Replies
dipak
Staff
Staff

Re: executeNDRangeKernel crashes with segfault under certain circumstances

Thanks for reporting this. It seems that clEnqueueNDRangeKernel crashes when it executes a device binary which contains any printf statement. The issue is also reproducible on other setups. A bug report has been filed against this issue. If I get any update, I'll share with you.

Regards,

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dipak
Staff
Staff

Re: executeNDRangeKernel crashes with segfault under certain circumstances

Hi,

Here is the resolution of the above issue.

On OCL1.2, printf is supported if a program is built from a source, but not if the program is built from a device binary. This is based on the design. This triggered the above crash. Though, a fix has been made to avoid the crash, however, nothing will be printed out because it’s not supported on OCL1.2. BTW, printf in a device binary is supported on OCL 2.0.

Note: The Catalyst driver with the above fix is yet not publicly available and hope, it will be released soon.

Regards,

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