topic Re: oneAPI 2025.3 DPC++ sycl hang in Intel® oneAPI DPC++/C++ Compiler

oneAPI 2025.3 DPC++ sycl hang

jimdempseyatthecove — Sat, 01 Nov 2025 15:45:28 GMT

Using oneAPI 2025.3 DPC++ hangs at startup where 2025.2 used to work.

Not, the hang occurs in a reduced program without sycl header.

IOW code equivalent to a "Hello World" hangs.

//#include <sycl/sycl.hpp> #include <iostream> int main() { std::cout << "Enumerate SYCL devices" << std::endl; // Get all available SYCL platforms //for (const auto& platform : sycl::platform::get_platforms()) { // std::cout << "Platform: " // << platform.get_info<sycl::info::platform::name>() // << std::endl; // // Get all devices for the current platform // for (const auto& device : platform.get_devices()) { // std::cout << " Device: " // << device.get_info<sycl::info::device::name>() // << std::endl; // // Query and print some key device properties // std::cout << " Vendor: " // << device.get_info<sycl::info::device::vendor>() // << std::endl; // std::cout << " Type: " // << (device.is_cpu() ? "CPU" : device.is_gpu() ? "GPU" : "Other") // << std::endl; // std::cout << " Max Compute Units: " // << device.get_info<sycl::info::device::max_compute_units>() // << std::endl; // std::cout << " Max Clock Frequency (MHz): " // << device.get_info<sycl::info::device::max_clock_frequency>() // << std::endl; // std::cout << " Global Memory Size (MB): " // << device.get_info<sycl::info::device::global_mem_size>() / 1024 / 1024 // << std::endl; // std::cout << " Double Precision Support: " // << (device.has(sycl::aspect::fp64) ? "Yes" : "No") // << std::endl; // } //} return 0; }

The hang point (IMHO) is waiting for a completion flag from the GPU,

00007FFA759B509F int 3 00007FFA759B50A0 cmp byte ptr [rcx+270h],0 00007FFA759B50A7 jne 00007FFA759B50C3 00007FFA759B50A9 nop dword ptr [rax] 00007FFA759B50B0 movzx eax,byte ptr [rcx+271h] 00007FFA759B50B7 nop 00007FFA759B50B8 test al,al 00007FFA759B50BA je 00007FFA759B50B0 00007FFA759B50BC mov byte ptr [rcx+270h],1 00007FFA759B50C3 ret 00007FFA759B50C4 int 3

Flag at [rcx+271h] never set

Call stack

Did something kill/replace the graphics driver? (e.g. Windows Update)

Jim Dempsey

Re: oneAPI 2025.3 DPC++ sycl hang

jimdempseyatthecove — Sat, 01 Nov 2025 16:11:47 GMT

Note, pausing the hung program, opening a disassembly window, then issuing a step, places the program counter at the nop instruction. Opening the al register and setting the value from 0 to 1, then continue, the program returns and issues the cout.

Uncommenting the commented statements and doing the same. Produces the expected results.

Enumerate SYCL devices Platform: Intel(R) oneAPI Unified Runtime over Level-Zero V2 Device: Intel(R) Arc(TM) Pro B50 Graphics Vendor: Intel(R) Corporation Type: GPU Max Compute Units: 128 Max Clock Frequency (MHz): 2600 Global Memory Size (MB): 15876 Double Precision Support: Yes Platform: Intel(R) OpenCL Device: Intel(R) Core(TM) i9-14900K Vendor: Intel(R) Corporation Type: CPU Max Compute Units: 32 Max Clock Frequency (MHz): 0 Global Memory Size (MB): 65291 Double Precision Support: Yes Platform: Intel(R) OpenCL Graphics Device: Intel(R) Arc(TM) Pro B50 Graphics Vendor: Intel(R) Corporation Type: GPU Max Compute Units: 128 Max Clock Frequency (MHz): 2600 Global Memory Size (MB): 15876 Double Precision Support: Yes Platform: Intel(R) OpenCL Device: Intel(R) Core(TM) i9-14900K Vendor: Intel(R) Corporation Type: CPU Max Compute Units: 32 Max Clock Frequency (MHz): 0 Global Memory Size (MB): 65291 Double Precision Support: Yes

Note 2, the hang occurs even after performing a repair on the driver (installed with gfx_win_101.6979.exe)

I do not know what changed.

Any information on a fix would be helpful.

Jim Dempsey

Re: oneAPI 2025.3 DPC++ sycl hang

Sravani_K_Intel — Mon, 03 Nov 2025 19:30:35 GMT

Please upgrade to the latest driver available for your system as this issue has been addressed in recent driver updates.