# Issue with SYCL compiler not supporting OpenMP **URL:** \ **Category:** User discussions\ **Created:** [August 20, 2024, 11:34am UTC](https://gromacs.bioexcel.eu/t/issue-with-sycl-compiler-not-supporting-openmp/9929 "2024-08-20T11:34:11Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Newsky](https://avatars.discourse-cdn.com/v4/letter/n/f05b48/32.png) [@Newsky](https://gromacs.bioexcel.eu/u/Newsky)\ **Post date:** [August 20, 2024, 11:34am UTC](https://gromacs.bioexcel.eu/t/issue-with-sycl-compiler-not-supporting-openmp/9929/1 "2024-08-20T11:34:11Z")
GROMACS version: Latest GROMACS modification: Yes/No ([Installation guide for exotic configurations - GROMACS 2024.1 documentation](https://manual.gromacs.org/2024.1/install-guide/exotic.html)) Regarding the SYCL oneApi build having OpenMP issue, there is following suggestion: For oneAPI 2024.x: `-DCMAKE_C_FLAGS="-isystem /opt/intel/oneapi/compiler/latest/opt/compiler/include" -DCMAKE_CXX_FLAGS="-isystem /opt/intel/oneapi/compiler/latest/opt/compiler/include"` However, I’m using open source dpc++ which does not have the suggested paths. Any ideas what I should use instead? Thanks ---
**Author:** ![al42and](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/al42and/32/1393_2.png) [@al42and](https://gromacs.bioexcel.eu/u/al42and)\ **Post date:** [August 20, 2024, 1:33pm UTC](https://gromacs.bioexcel.eu/t/issue-with-sycl-compiler-not-supporting-openmp/9929/2 "2024-08-20T13:33:53Z")
Hi! If you’re building DPC++ itself, just build it with OpenMP: `python3 ../buildbot/configure.py --llvm-external-projects=openmp [whatever other options]` After building and installing it, GROMACS should detect OpenMP support without any extra flags (you might want to purge GROMACS’s CMake cache in the build directory). Note: Open-source DPC++ and Unified Runtime are moving fast, so beware of bugs or API changes when using the tip of `sycl` branch (or any of the nightly snapshots for that matter). ---
**Author:** ![Newsky](https://avatars.discourse-cdn.com/v4/letter/n/f05b48/32.png) [@Newsky](https://gromacs.bioexcel.eu/u/Newsky)\ **Post date:** [August 21, 2024, 2:26pm UTC](https://gromacs.bioexcel.eu/t/issue-with-sycl-compiler-not-supporting-openmp/9929/3 "2024-08-21T14:26:20Z")
Hey, After trying that, I’m still having the same issue. (Tried to make a fresh build) ```auto CMake Error at cmake/gmxManageOpenMP.cmake:50 (message): The compiler you are using does not support OpenMP parallelism. This might hurt your performance a lot, in particular with GPUs. Try using a more recent version, or a different compiler. If you don't want to use OpenMP, disable it explicitly with -DGMX_OPENMP=OFF Call Stack (most recent call first): CMakeLists.txt:432 (include) ``` There seems to be something off with the dpc++ build as I cannot find libomp.so anywhere. ---
**Author:** ![al42and](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/al42and/32/1393_2.png) [@al42and](https://gromacs.bioexcel.eu/u/al42and)\ **Post date:** [August 21, 2024, 3:20pm UTC](https://gromacs.bioexcel.eu/t/issue-with-sycl-compiler-not-supporting-openmp/9929/4 "2024-08-21T15:20:16Z")
That’s weird. I just made a clean build of the open-source Intel LLVM compiler (07bf3c11ebeafbbb408708dd79f578ec7c974423) using `python3 ../buildbot/configure.py --cuda --hip -t release --llvm-external-projects=openmp` After building, I have `./projects/openmp/runtime/src/omp.h` and `./lib/libomp.so` in the build directory. Installing puts them to `{install_prefix}/lib/clang/19/include/omp.h` and `{install_prefix}/lib/x86_64-unknown-linux-gnu/libomp.so`. ---
**Author:** ![Newsky](https://avatars.discourse-cdn.com/v4/letter/n/f05b48/32.png) [@Newsky](https://gromacs.bioexcel.eu/u/Newsky)\ **Post date:** [August 22, 2024, 8:30am UTC](https://gromacs.bioexcel.eu/t/issue-with-sycl-compiler-not-supporting-openmp/9929/5 "2024-08-22T08:30:44Z")
Hmm, I’m really bad at setting up LLVM, but here is what I got (with ad59feb6210ae8dab5e73f61e05631261039498b): ```auto $ python3 configure.py -o ../build_default --llvm-external-projects=openmp -t Release $ python3 compile.py -o ../build_default -j 70 ``` I have omp.h at `/build_default/projects/openmp/runtime/src` No libomp.so at `/build_default/lib` No omp.h at `/build_default/install/lib/clang/19/include` No libomp.so (and not any directories) at `/build_default/install/lib` By looking at ccmake, I have `CLANG_DEFAULT_OPENMP_RUNTIME libomp`, `LLVM_ENABLE_PROJECTS clang;sycl;llvm-spirv;opencl;xpti;xptifw;libdevice;sycl-jit;openmp` Could openmp library be somehow statically linked? Anyway, gromacs still complains about the lacking support. ---
**Author:** ![al42and](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/al42and/32/1393_2.png) [@al42and](https://gromacs.bioexcel.eu/u/al42and)\ **Post date:** [August 22, 2024, 11:02am UTC](https://gromacs.bioexcel.eu/t/issue-with-sycl-compiler-not-supporting-openmp/9929/6 "2024-08-22T11:02:17Z")
> Could openmp library be somehow statically linked? The OpenMP library could perhaps be statically linked to the application (GROMACS), but building Clang should still produce a library file (`libomp.so` or `libomp.a`) for that linking to happen. We’re not linking OpenMP to Clang; we build OpenMP library that should later be linked to GROMACS. > Hmm, I’m really bad at setting up LLVM, but here is what I got IMO, that is a question better answered at [intel/llvm · Discussions · GitHub](https://github.com/intel/llvm/discussions). The problem is that LLVM does not build OpenMP, that’s not related to GROMACS. That said, compared to your example, I usually directly call `cmake --build . && cmake --build . --target sycl-toolchain sycl-sanitize sycl-trace install deploy-sycl-toolchain` in the build directory instead of using `compile.py`. ---
**Author:** ![Newsky](https://avatars.discourse-cdn.com/v4/letter/n/f05b48/32.png) [@Newsky](https://gromacs.bioexcel.eu/u/Newsky)\ **Post date:** [August 22, 2024, 11:45am UTC](https://gromacs.bioexcel.eu/t/issue-with-sycl-compiler-not-supporting-openmp/9929/7 "2024-08-22T11:45:33Z")
Yeah, I agree. Thanks!