OpenCL Extensions available in Intel® SDK for OpenCL™ Applications
The following tables contain information about extensions to the Khronos Group OpenCL™ standard available for Intel processors.
Notice: Not all extensions are available in all versions of the OpenCL drivers for each OS. Some features are only available on certain hardware platforms or in certain driver baselines.
Preview Extensions
General info on preview extensions: /content/www/us/en/develop/articles/intel-opencl-experimental-features.html
Media Extensions
These extensions enable video processing applications to access hardware features in Intel processors.
| Extension Name | Description | Supported HW Notes |
|---|---|---|
| cl_intel_device_side_avc_motion_estimation | See below. Provides programmers with a macroblock-level interface to the motion estimation functionality available in the Intel graphics processor media sampler. It describes the specification of low-level built-in functions, callable from OpenCL kernels, to evaluate AVC motion estimation operations. It covers everything the host side motion estimation extensions can do and more. Sample: Intro to Device Side AVC Motion Estimation |
Gen9 (new in Linux SRB4, not yet available for Windows.) |
| cl_intel_advanced_motion_estimation cl_intel_motion_estimation |
Provides a frame-level interface implemented as built-in kernels to accelerate motion estimation operations. Supports AVC block sizes, inter/intra estimation, skip checks, and motion vector costing.
Notes:
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| cl_intel_packed_yuv | YUV is usually a planar format. This extension provides support for a few specific formats of packed YUV images. More info: Spec | |
| cl_intel_planar_yuv |
Provides support for the Planar YUV (YCbCr) image formats. More info: Spec |
Gen9 (new in Linux SRB4, not yet available for Windows.) |
| cl_intel_media_block_io | Built-in functions to facilitate the reading and writing of flexible 2D regions from images. Augments Intel vendor extensions cl_intel_subgroups and cl_intel_subgroups_short. More info: Spec |
Gen9 (new in Linux SRB4, not yet available for Windows.) |
VEBox preview extensions:
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Built-in functions to work with VEBox. Samples: Minimal VEBox Samples More info: OpenCL Preview Extensions for VEBox |
Gen9 (new in Linux SRB4, not yet available for Windows.) |
Sharing Extensions
This group of extensions enables interoperability between OpenCL and other APIs using Intel GPUs.
| Extension Name | Description | Supported HW Notes |
|---|---|---|
| cl_intel_simultaneous_sharing | The OpenCL 1.2 Extension Spec forbids interoperability with multiple graphics APIs at clCreateContext or clCreateContextFromType time. It defines that CL_INVALID_OPERATION should be returned in such cases. The goal of this extension is to relax the restrictions and allow simultaneous use of API combinations as supported by a given OpenCL device. More info: Spec | |
| cl_intel_va_api_media_sharing | Linux/Android Media Sharing More info: Spec See /content/www/us/en/develop/articles/tutorial-opencl-interoperability-with-video-acceleration-api-on-linux-os.html Used in Media Server Studio samples | |
| cl_intel_d3d11_nv12_media_sharing cl_intel_dx9_media_sharing |
Windows sharing APIs (created before Khronos extensions below.) Used in Media Server Studio samples More info: |
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| cl_khr_dx9_media_sharing cl_khr_d3d10_sharing cl_khr_d3d11_sharing |
Sharing for DirectX 9, 10, 11 /content/www/us/en/develop/articles/opencl-and-intel-media-sdk.html More info: |
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| cl_khr_gl_sharing cl_khr_gl_msaa_sharing cl_khr_gl_depth_images cl_khr_gl_event |
Sample: https://software.intel.com/sites/default/files/managed/2c/79/intel_ocl_ogl_interop_win.zip Related Pages: /content/www/us/en/develop/articles/opencl-and-opengl-interoperability-tutorial.html More info: gl_sharing Spec gl_msaa_sharing Spec gl_depth_images Spec gl_event Spec |
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Subgroups Extensions
Work items in a subgroup can share data without implementing shared local memory or using barriers. This extends the work group concept to allow more efficient data sharing.
| Extension Name | Description | Supported HW Notes |
|---|---|---|
| cl_intel_subgroups | Enables work-items in a workgroup to work together let work items share data without local memory and global barriers. Similar to OpenCL 2.0 workgroups. /content/www/us/en/develop/articles/sgemm-ocl-opt.html /content/www/us/en/develop/articles/sgemm-for-intel-processor-graphics.html /content/www/us/en/develop/articles/box-blur-filter-using-intel-subgroup-extensions-in-opencl.html More info: Spec | |
| cl_intel_required_subgroup_size | The goal of this extension is to allow programmers to optionally specify the required subgroup size for a kernel function. This information is important for the correctness of many subgroup algorithms, and in some cases may be used by the compiler to generate more optimal code. More info: Spec | |
| cl_khr_subgroups | Implementation controlled division of a workgroup allowing independent forward progress within the workgroup. This feature was promoted to Core in OpenCL 2.1. More info: Spec | |
| cl_intel_subgroups_short |
Improve the performance of applications operating on 16-bit data types by extending the subgroup functions described in the cl_intel_subgroups extension to support 16-bit integer data types (shorts and ushorts). More info: Spec |
Other Extensions
| Extension Name | Description | Supported HW Notes |
|---|---|---|
| cl_intel_accelerator |
Basic accelerator support
The accelerator extension consists of a unified set of OpenCL runtime APIs to create, query, and manage the lifetime of objects which represent acceleration processors, engines, or algorithms. More info: |
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| cl_intel_driver_diagnostics | This extension allows the driver to pass additional strings containing diagnostic information. The diagnostic messages can help to understand how the driver works and can provide guidance to modify an application to improve performance. More info: |
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| cl_khr_3d_image_writes | Enables writes to 3D image objects More info: Spec | |
| cl_khr_byte_addressable_store | Removes restrictions of built-in types. Needed to write to elements of a pointer or struct of type char, uchar, char2, uchar2, short, ushort, and half. More info: Spec | |
| cl_khr_spir |
OpenCL Standard Portable Intermediate Representation (SPIR) non source representation of OpenCL. More info: Spec |
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| cl_khr_fp16 | Half-precision floating-point More info:Spec | |
| cl_khr_fp64 | IEEE-754 double-precision floating-point support More info: Spec | |
| cl_khr_global_int32_base_atomics | 32-bit integer base atomic operations in global memory More info: Spec | |
| cl_khr_global_int32_extended_atomics | 32-bit integer extended atomic operations in global memory More info: Spec | |
| cl_khr_icd |
Access Khronos OpenCL installable client driver loader (ICD Loader) More info: Spec |
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| cl_khr_image2d_from_buffer | 2D image from buffer creation support More info: | |
| cl_khr_mipmap_image cl_khr_mipmap_image_writes | Ability to create / read mipmapped images Adds ability to write mipmapped images, requires cl_khr_mipmap_image More info:Spec |
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| cl_khr_depth_images | Depth Images More info: Spec | |
| cl_khr_throttle_hints | Extension to OpenCL 2.1 API which allows the driver to implement throttling behavior. Throttling behavior is implementation specific. More info: Spec | |
| cl_khr_local_int32_base_atomics cl_khr_local_int32_extended_atomics |
base_atomics: Spec extended_atomics: Spec |
Deprecated Extensions
| Extension Name | Description |
|---|---|
| cl_intel_ctz | Built-in count trailing zeroes |