How to setup Intel C-for-media development environment. GPGPU programming on Intel GEN graphics.

Evgeny Fedorov
Jul 31 · 4 min read
Photo by Shahadat Shemul on Unsplash

The Intel C-for-Media compiler(CMC) is an open source compiler that implements C-for-Media (CM) programming language. CM is a new GPU kernel programming language for Intel HD Graphics. CMC is available for Linux and Windows systems. Current article is focused on Linux one as it’s a main development platform of the author.

If you are a windows user installation is pretty easy:

  1. Get Intel C for Media package
  2. Extract package in desired directory <install_dir>
  3. Set environment variable INSTALLDIR = <install_dir>

Linux is where things became interesting as there some inconsistencies between libraries.

Ok, lets go and run your first GPU kernel program.


Step 1. Set the environment

1.1 Hardware

Any CPU with intel graphic GEN 9 or higher onboard. Kabylake is used for current article.

2.2 Software

Is pretty flixible. Only fresh compiler is desirable. Here is what I used:

  • CentOS 7.6
  • CMake 3.12
  • GCC 8.2
  • git 1.8
  • make 3.82
  • Python 3.5

Step 2. Build and install CMC toolchain

To develop GPU kernels using CMC we need follow packages:

  • The Intel(R) C-for-Media compiler — Clang based open source compiler for creating GPU kernels.
  • Libva — an implementation for open-source Video Acceleration API (VA-API), which provides access to graphics hardware acceleration capabilities for video processing.
  • Intel(R) Media Driver for VA-API — user mode driver.
  • Intel Graphics Compiler for OpenCL™ — an LLVM based compiler for OpenCL™.

Lets process through all steps:

2.1 Build and install libva
There is a simple way to build this component using cmake build system.

git clone https://github.com/intel/libva.git libva
cd libva
./autogen.sh --with-drivers-path=/opt/intel/mediasdk/lib64/ --prefix=/usr --libdir=/usr/lib64
make -j8
sudo make install
cd ..

2.2 Build and install Intel(R) Media Driver for VA-API
Media driver also can be built using cmake.

git clone https://github.com/intel/media-driver.git media-driver
git clone https://github.com/intel/gmmlib.git

After these steps driver and CM runtime are installed in the system:

  • User mode driver: /opt/intel/mediasdk/lib64
  • Runtime libraries: /usr/local/lib64
  • Runtime headers: /usr/local/include/igfxcmrt

2.3 Build and install Intel(R) C-for-Media compiler
Build compiler where “-i” param specifies output directory. Lets call it <cmc_install_dir>, it will be needed later.

git clone https://github.com/intel/cm-compiler.git cm-compiler
cd cm-compiler
support/scripts/build.bash -d -c -p /usr/local/bin -i `pwd`/../bin

Copy “test” directory which containes examples into <cmc_install_dir>:

cp test ../bin -r
cd ../bin

Edit examples makefile:

  • Add path to CMC runtime headers from first step to “INCL” set.
  • Update path to runtime library (igfxcmrt.so) in compilation command.
  • Change path to compilers headers in HW_CMCFLAGS to <cmc_install_dir>/include.
  • Add path to cmc compiler binary.

This can be achivied using follow command:

sed -i 's/-I$(CM_ROOT)\/runtime\/include/-I\/usr\/local\/include\/igfxcmrt\ -I\/usr\/include\/libdrm/' test/open_examples/Makefile.linux
sed -i "s@^CMC :=@CMC := `pwd`\/bin\/cmc\ #@" test/open_examples/Makefile.linux
sed -i "s@\$(CM_ROOT)/runtime/lib/x64/igfxcmrt64.so@/usr/local/lib64/libigfxcmrt.so@" test/open_examples/Makefile.linux

2.4 Build Intel Graphics Compiler for OpenCL™
Clone compiler and build it accordance to instructions.

git clone https://github.com/intel/intel-graphics-compiler.git igc
git clone -b release_80 https://github.com/llvm-mirror/llvm llvm_source
git clone -b release_80 https://github.com/llvm-mirror/clang llvm_source/tools/clang
git clone -b ocl-open-80 https://github.com/intel/opencl-clang llvm_source/projects/opencl-clang
git clone -b llvm_release_80 https://github.com/KhronosGroup/SPIRV-LLVM-Translator llvm_source/projects/llvm-spirv
git clone https://github.com/intel/llvm-patches llvm_patches

Only Genx_IR tool is required from this package so just copy it to <cmc_install_dir>/bin

cp Release/Tools/GenX_IR ../bin/bin/

2.5 Installation notes

There are two ways to load and execuite GPU kernel programs. With Just-in-time compilation and without.

  • JIT way. In this way step 2.4 is not needed but you will need jitter library which is provided with CM runtime from github (https://github.com/intel/cmrt.git).
    NOTE: library provided as binary file built by gcc-4.8.2, so if you want to use it you should build all environment and your code by this compiler.
  • “Nojitter” way. In this case you don`t need jitter library, but you should specify target architecture and add “nojitter” string as last argument to LoadProgram call in example code.

I’m preferring nojitter way and focus this article only on it.

Step 3. Run samples

3.1 Modify samples to work in “nojitter” mode

Edit example smakefile from step 2.3.

Create variableGEN_MODE and set it to target platform. I setKBL as using KabyLake based graphics.

  1. Add following flags to HW_CMCFLAGS to specify target platform:
  • -Qxcm_jit_target=$(GEN_MODE)
  • -Qxcm_vme_arch=$(GEN_MODE)

2. Add some other useful flags:

  • -Qxcm (not necessary, it enabled by default as described by intel, but I recommend to add it)
  • -Qxcm_opt_report (errors reporting)
  • -Qxcm_print_asm_count (to output count of assembly instructions)

3. Update paths to CMC and runtime library.

Example script to do these steps:

sed -i "s@-march=\$(GEN_MODE)@-isystem `pwd`/include -Qxcm_jit_target=\$(GEN_MODE) -Qxcm_opt_report -Qxcm_print_asm_count -Qxcm_vme_arch=\$(GEN_MODE) -Qxcm #@" test/open_examples/Makefile.linux

3.1 Build and run sample

Now lets run any sample, E.g. histogram_64

For this change LoadProgram call to “nojitter”, then build and run example:

cd ../bin/test/open_examples/histogram_64
sed -i "s@program));@ssprogram,\"nojitter\"));@" histogram.cpp
make -f ../Makefile.linux
./hw_x64.histogram_64

That is it! Now you are ready to create your own GPU kernels to run them on Intel graphics. In the next article we will create one.

vicuesoft-techblog

ViCueSoft.com Technology Blog

Evgeny Fedorov

Written by

Engineering Manager at VicueSoft.com

vicuesoft-techblog

ViCueSoft.com Technology Blog

Welcome to a place where words matter. On Medium, smart voices and original ideas take center stage - with no ads in sight. Watch
Follow all the topics you care about, and we’ll deliver the best stories for you to your homepage and inbox. Explore
Get unlimited access to the best stories on Medium — and support writers while you’re at it. Just $5/month. Upgrade