Under Windows and Mac the Intel GPU drivers include OpenCL support; however, on Linux OpenCL on Intel GPUs is implemented through an open source project called Beignet (pronnounced like "ben-yay", a type of French pastry akin to a what we would call a "fritter" in English). Below I have written a step-by-step guide on how you can get Beignet running on an Ubuntu 14.10 system which has an Intel 3rd, 4th, or 5th generation Intel processor. Instructions for other variants of Linux will be similar, except for the commands to install the prerequisite packages.
There are several little caveats which need to be discussed up front. Foremost, the Beignet project supports the following hardware:
- 3rd Generation Intel Core Processors
- Intel “Bay Trail” platforms with Intel HD Graphics
- 4th Generation Intel Core Processors (requires a kernel patch be applied for shared memory!)
- 5th Generation Intel Core Processors "Broadwell".
There are also a few noteworthy issues of which you should be aware:
- If your computer is running a Linux kernel in the 3.15 or 3.16 branch, you will need to disable some register whitelist functionality every time you reboot your system. This can be accomplished by running
echo 0 > /sys/module/i915/parameters/enable_cmd_parser
as root. - 4th Generation Intel Processors (i.e. i3/5/7-4xxx) require a kernel patch for shared/local memory to function.
- There is no double precision support
- OpenGL-OpenCL interop via
cl_khr_gl_sharing
is not supported
There are additional release notes that can be found on the Beignet project page.
Installing prerequisites
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sudo apt-get install build-essential g++ cmake sudo apt-get install clang libclang-3.5-dev libclang-dev libclang1 sudo apt-get install ocl-icd-opencl-dev ocl-icd-libopencl1 |
libclang-3.4-dev
instead, then run update-alternatives
to point llvm-link
and llvm-as
to the correct version. The latter can be accomplished using the following commands:
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sudo update-alternatives --install /usr/bin/llvm-link llvm-link /usr/bin/llvm-link-3.4 34 sudo update-alternatives --install /usr/bin/llvm-as llvm-as /usr/bin/llvm-as-3.4 34 |
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sudo apt-get install opencl-headers ocl-icd-dev ocl-icd-libopencl1 |
clinfo
program so that you can verify that your installation is successful:
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sudo apt-get install clinfo |
Check out and compile Beignet
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git clone git://anongit.freedesktop.org/beignet cd beignet git checkout Release_v1.0.0 mkdir build cd build cmake .. |
During the CMake stage, ensure that the OCL ICD header file is installed, otherwise the library will not create an installable client driver. If everything went fine, go ahead and compile the source using
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make |
(Note, you can do make -jN with N > 1 to do a parallel build.)
Next we verify that Beignet is functioning correctly on your hardware by running unit tests. These can be found in the utest
folder. The unit tests require some enviornmental variables be set prior to invocation:
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cd utests source setenv.sh ./utest_run |
If a significant fraction of the unit tests fail and you have a 3.15 or 3.16 kernel, you need to disable register whitelisting using a command similar to the following:
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sudo su echo 0 > /sys/module/i915/parameters/enable_cmd_parser exit |
and try re-running the tests. Please note that this change is not permanent and you will need to re-run it if you reboot your system. Alternatively, you could add this command to a startup script. The Beignet release notes mention there is a kernel patch to fix this issue which you could backport if you so desired.
If most of the tests pass, but those that involve local memory (~20-30 of the tests) fail, you will need to apply the kernel patch listed below.
If all was well, install Beignet to your system:
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sudo make install |
You can see a list of installed software in the install_manifest.txt
file in the build directory.
Verify Beignet is installed
In a terminal run the clinfo
program. You should see something like this:
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$ clinfo ... Platform Name: Intel Gen OCL Driver Number of devices: 1 Device Type: CL_DEVICE_TYPE_GPU ... Name: Intel(R) HD Graphics Haswell GT2 Desktop Vendor: Intel Device OpenCL C version: OpenCL C 1.2 beignet 0.9.1 Driver version: 0.9.1 Profile: FULL_PROFILE Version: OpenCL 1.2 beignet 0.9.1 Extensions: cl_khr_global_int32_base_atomics cl_khr_global_int32_extended_atomics cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics cl_khr_byte_addressable_store cl_khr_icd |
Take note that the Intel OpenCL driver is loaded for a GPU device using beignet
. This indicates the Installable Client Driver (ICD) is correctly installed. Also note the extensions listed.
Applying the kernel patch to enable OpenCL shared local memory.
If you are using Beignet on a 4th generation Intel processor, you will need to apply a kernel patch to enable shared/local memory. This is a fairly lengthy process that will require at least 70 GB of hard disk space and perhaps an hour of compilation time if the build is executed in parallel.
In the next few paragraphs I'll walk you through how you can apply the kernel patch. I have based my instructions on the kernel compilation instructions for Ubuntu. Instructions for other variants of Linux will be significantly different.
Install prerequisites:
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sudo apt-get build-dep linux-image-`uname -r` |
Make a working directory for the kernel somewhere and download the source
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mkdir kernel cd kernel apt-get source linux-image-`uname -r` |
Next we see if we can automatically apply the patch. First download the patch:
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wget https://01.org/sites/default/files/disable-batchbuffer-security.patch |
Now cd
into the kernel directory:
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cd linux-3.16.0 |
Check some details about the patch
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git apply --stat ../disable-batchbuffer-security.patch |
Try automatically applying the patch:
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git apply --check ../disable-batchbuffer-security.patch |
If it automatically applies with no errors, just apply it:
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git apply ../disable-batchbuffer-security.patch |
If it did not work (as was the case on my system), the change is fairly simple. Open the drivers/gpu/drm/i915/i915_gem_execbuffer.c
file in an editor:
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gedit drivers/gpu/drm/i915/i915_gem_execbuffer.c |
In the i915_gem_do_execbuffer
function, find the following code:
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flags = 0; if (args->flags & I915_EXEC_SECURE) { if (!file->is_master || !capable(CAP_SYS_ADMIN)) return -EPERM; |
And add the line flags |= I915_DISPATCH_SECURE;
as follows:
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flags = 0; flags |= I915_DISPATCH_SECURE; if (args->flags & I915_EXEC_SECURE) { if (!file->is_master || !capable(CAP_SYS_ADMIN)) return -EPERM; |
This was inserted on line 998 for me. Save the file. Now we need to compile and install the modified kernel.
Now we build the new kernel. Run the following commands from within the kernel source directory:
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fakeroot debian/rules clean DEB_BUILD_OPTIONS=parallel=8 fakeroot debian/rules binary-headers binary-generic |
This will build some Debian packages and place them in the directory above the kernel source root.
After the kernel has compiled, install it:
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cd ../ (or go back into the kernel directory) sudo dpkg -i linux-headers-3.16.0-29-generic_3.16.0-29.54_amd64.deb sudo dpkg -i linux-image-3.16.0-29-generic_3.16.0-29.54_amd64.deb |
(you might have to change the numeric kernel version to match what you compiled) Now add the kernel to the boot options:
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sudo update-grub sudo reboot |
Now go back and re-run the Beignet unit test framework from above. With any luck everything will work fine.




