About the Intel® FPGA Emulation Platform for OpenCL™

Intel® FPGA Emulation Platform for OpenCL™ technical preview includes the runtime and compiler, which runs on Intel® Core™ and Intel® Xeon® processors. It is capable of compiling and running programs written with Intel® OpenCL™ FPGA extensions (for example, with the FPGA 'channels' extension).

The emulator aims to provide:

• rapid compilation time (seconds)
• source code portability between emulator and FPGA
• reasonable performance (average benchmarks run at 5x-10x slowdown in comparison with FPGA hardware)

This version of the emulator is a technical preview, and it does not provide full functional equivalence with an FPGA device. It is provided for evaluation purposes only without any warranties.

System Requirements

Refer to theIntel® oneAPI DPC++ Compiler and Intel® oneAPI DPC++ Library System Requirements.

Installing Intel® FPGA Emulation Platform for OpenCL™ Technical Preview

To configure environment of current session for using OpenCL™ standalone binaries do the following steps:

1. Unpack provided binaries to any working directory
2. Create new .icd file with following content as shown below:
   echo /path/to/binaries/libintelocl_emu.so >> /etc/OpenCL/vendors/intel_fpga_fast_emu.icd
3. Set INSTALLDIR variable in setupvars.sh script to the path where binaries have been unpacked.

If installation succeeded the following OpenCL™ platform will be available:

Platform [#1] :

Profile : FULL_PROFILE

Version : OpenCL 2.0 LINUX

Name : Intel(R) FPGA Emulation Platform for OpenCL(TM) (preview)

Vendor : Intel(R) Corporation

Devices : 1

Device [#1] :

Type : accelerator

Profile : FULL_PROFILE

Version : OpenCL 2.0 (Build 5)

Name : Intel(R) FPGA Emulation Device (preview)

Vendor : Intel(R) Corporation

C version : OpenCL C 2.0

Driver version : 1.2.0.5

Getting Started with Intel® FPGA Emulation Platform for OpenCL™ Technical Preview

The emulator provides a separate OpenCL™ platform with one OpenCL™ CPU device. It supports Intel® FPGA OpenCL™ extensions.

OpenCL programs written for FPGA device can be compiled and executed on this device, using standard OpenCL API (including clCreateProgramWithBinary(), see the Offline Compilation section).

There are sets of environment variable affecting emulator execution.

• The set of emulator specific libraries:
  • OCL_FPGA_EMU - should be set to enable FPGA style of channels. This environment variable is mandatory to use FPGA specific extensions.

  • OCL_TBB_NUM_WORKERS ([1..]) - maximum number of threads which can be used by TBB.

  • VOLCANO_CPU_ARCH (core-avx2, skx) - can be set to force SIMD instruction set used for OpenCL kernel compilation where skx corresponds to AVX-512 support

  • VOLCANO_CLANG_OPTIONS - internal environment variable allowing to force some options to OpenCL compiler. For example:

    • -fopenmp -fintel-openmp -fopenmp-tbb - enables OpenMP* support

    • -ffast-math - forces fast math built-ins

    • -DINTEL_OCL_FPGA_CPU_EMU - adds corresponding define to the OpenCL kernel

  • VOLCANO_LLVM_OPTIONS (-vector-library=SVML) - Internal option that allows force usage of short vector math library. Must be set if OpenMP support is enabled.

• OpenCL related environment variables:
  • CL_CONFIG_USE_VECTORIZER (True, False) - NDRange vectorizer control. Does not affect OpenMP pragma vectorization of single work-item kernels. Should be set to False to speedup kernel compilation time.

  • CL_CONFIG_CPU_FORCE_LOCAL_MEM_SIZE (e.g 256KB) - amount of available OpenCL local memory.

• OpenMP environment variables (see OpenMP documentation for details):
  • KMP_AFFINITY - affinity settings for OpenMP threads. For example, "norespect,physical,20"
  • OMP_NUM_THREADS ([1..]) - Number of available OpenMP threads

Optimization guide using OpenMP is available in the directory with binaries (Optimization_guide.pdf).

Offline Compilation

The Emulator supports OpenCL™ kernels compilation into binaries (similar to .aocx files used for FPGA device), which can be used in clCreateProgramWithBinary().

Use Intel® SDK for OpenCL™ Applications - offline compiler ('ioc64' tool) to compile kernel binaries for the emulator from OpenCL C source code. This tool is distributed as part of Intel® Code Builder for OpenCL™ API:

> ioc64 -bo='-cl-std=CL2.0' -device-fpga_fast_emu -input=source.cl -ir=kernel_binary.elf

Name for the output file is arbitrary, and it can have .aocx extension to let a host program use the same names for both FPGA device and the emulator.

Kernel binaries produced by the 'ioc' tool are not compatible with binaries compiled for FPGA device and vice versa.

Execution

Set of environment variables mentioned in the Getting Started section can affect the emulator behavior.

Bash script (setupvars.sh) distributed with binaries can be used to simplify the environment setting. Please uncomment/modify value for required variable in the script and run the command below:

> . /path/to/binaries/setupvars.sh

After that all application running in current console will use environment variables set in the script.