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2019.1 SDAccel™ Development Environment Tutorials

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Controlling Vivado Implementation

Introduction

The SDAccel™ environment XOCC compiler creates kernel objects from the source code, links the kernels with the targeted shell, and runs the assembled design through the Vivado® tool implementation flows. It generates the platform file (xclbin) needed to program the FPGA-based acceleration cards. Sometimes, it is essential to use the advanced Vivado synthesis and implementation options to achieve your desired results, including timing closure.

Tutorial Overview

This tutorial shows you how to control the Vivado tool flows when implementing your project and guides you through the steps in the command line flow.

The SDAccel environment provides two methods to control the Vivado tool flow:

  1. When compiling or linking for a system build, you can pass Vivado synthesis and implementation options using the XOCC --xp switch.

    NOTE: It can take hours to complete a system run.

  2. If your application has already been compiled, then you can:

    • Optimize the design with the Vivado Design Suite.
    • Generate a new routed checkpoint.
    • Reuse this checkpoint to generate a new platform file (xclbin).

Before You Begin

This tutorial uses:

  • BASH Linux shell commands
  • 2019.1 SDx™ release and the xilinx_u200_xdma_201830_1 platform. If necessary, it can be easily ported to other versions and platforms.

IMPORTANT:

  • Before running any of the examples, make sure you have installed Xilinx Runtime (XRT) and the SDAccel development environment as described in the SDAccel Development Environment Release Notes, Installation, and Licensing Guide (UG1238).
  • If you run applications on the Alveo™ card, ensure the card and software drivers have been correctly installed by following the instructions in the Getting Started with Alveo Data Center Accelerator Cards Guide (UG1301).
  • Before running this lab, you must be familiar with the Essential Concepts for Building and Running the Accelerated Application tutorial.

Accessing the Tutorial Reference Files

  1. To access the reference files, enter the following into a terminal: git clone https://github.com/Xilinx/SDAccel-Tutorials.
  2. Navigate to SDAccel-Tutorials-master/docs/controlling-vivado-impl/reference-files/run.

Using the --xp XOCC Switch

NOTE: In this tutorial, run all instructions from the reference-files/run directory.

The –-xp switch is paired with parameters to configure the Vivado tools. For instance, the --xp switch can configure optimization, placement, and timing, or set up emulation and compile options. In the command line flow, parameters are specified as param:<param_name>=<value>, where:

  • param: Required keyword.
  • param_name: Name of a parameter to apply.
  • value: Appropriate value for the parameter.

In this section, you will use the following configurations as examples to see the flow to control Vivado synthesis and implementation:

  • Completely flatten hierarchy during RTL synthesis (specify FLATTEN_HIERARCHY=full).

    • --xp vivado_prop:run.my_rm_synth_1.{STEPS.SYNTH_DESIGN.ARGS.FLATTEN_HIERARCHY}={full}

  • Use the NoTimingRelaxation directive during the routing step (DIRECTIVE=NoTimingRelaxation).

    • --xp vivado_prop:run.impl_1.{STEPS.ROUTE_DESIGN.ARGS.DIRECTIVE}={NoTimingRelaxation}

NOTE: You can specify the -–xp command option multiple times in a single xocc invocation, or specify the values in an xocc.ini file with each option specified on a separate line without the --xp switch.

For a full list of parameters and valid values, refer to the SDx Command and Utility Reference Guide (UG1279).

  1. Before running any of the examples, ensure you have set up the SDx tools, platform, and runtime by running these commands:

    #setup Xilinx SDx tools, XILINX_SDX and XILINX_VIVADO will be set in this step. source <SDX install path>/settings64.sh. for example:
source /opt/Xilinx/SDx/2019.1/settings64.sh
#Setup runtime. XILINX_XRT will be set in this step
source /opt/xilinx/xrt/setup.sh

  2. Compile kernel with XOCC, and link it into the platform file (xclbin) with the --xp command options.

    xocc -t hw --platform xilinx_u200_xdma_201830_1 -g --max_memory_ports apply_watermark -c -k apply_watermark -o'apply_watermark.hw.xilinx_u200_xdma_201830_1.xo' '../src/krnl_watermarking.cl'
xocc -t hw --platform xilinx_u200_xdma_201830_1 -g --sp apply_watermark_1.m_axi_gmem0:DDR[0] --sp apply_watermark_1.m_axi_gmem1:DDR[1] -s --xp vivado_prop:run.my_rm_synth_1.{STEPS.SYNTH_DESIGN.ARGS.FLATTEN_HIERARCHY}={full} --xp vivado_prop:run.impl_1.{STEPS.ROUTE_DESIGN.ARGS.DIRECTIVE}={NoTimingRelaxation} -R2 -l --nk apply_watermark:1:apply_watermark_1 -o'apply_watermark.hw.xilinx_u200_xdma_201830_1.xclbin' apply_watermark.hw.xilinx_u200_xdma_201830_1.xo

    The following list describes some of the previous command options.

    Command Options Descriptions

    • -t hw: Target system run
    • --platform xilinx_u200_xdma_201830_1: Target the xilinx_u200 platform
    • -g: Generate debug info
    • --max_memory_ports apply_watermark: Generate one AXI4 interface for one port
    • -c: Compile the kernel
    • -k apply_watermark: Name the kernel
    • ../src/krnl_watermarking.cl: Specify source files
    • --sp apply_watermark_1.m_axi_gmem0:DDR[0] --sp apply_watermark_1.m_axi_gmem1:DDR[1]: Specify DDR bank connection
    • --xp vivado_prop:run.my_rm_synth_1.{STEPS.SYNTH_DESIGN.ARGS.FLATTEN_HIERARCHY}={full} --xp vivado_prop:run.impl_1.{STEPS.ROUTE_DESIGN.ARGS.DIRECTIVE}={NoTimingRelaxation}: Set the Vivado Synthesis and Implementation options
    • -R2: Set Report Level to 2 to generate DCPs for each implementation step
    • -l: Link the kernel
    • --nk apply_watermark:1:apply_watermark_1: Specify kernel instance number and name

  3. To check that the Vivado synthesis and implementation options are applied, open _x/logs/link/vivado.log, and search for flatten_hierarchy and NoTimingRelaxation. You will find following lines indicating that the options have taken effect:

    • Command: synth_design -top pfm_dynamic -part xcu200-fsgd2104-2-e -flatten_hierarchy full -mode out_of_context
    • Command: route_design -directive NoTimingRelaxation

Optimizing with the Vivado Tool

If your application has already been compiled for a system run, you can optimize the implementation result with various Vivado tool techniques to achieve your goal, such as achieving timing closure. After optimization, write the routed design back to checkpoint file (DCP), and then reuse this checkpoint to finalize a new implementation.

NOTE: Ensure that the SDx environment and Vivado environment versions match between different iterations.

In the optimization stage, Vivado tool techniques apply. For information on Vivado tool usage and optimization, refer to the Vivado Design Suite Implementation User Guide (UG904) and UltraFast Design Methodology Guide for the Vivado Design Suite (UG949).

For example, you might run the Vivado tool in batch mode with a Tcl script, where the Tcl script reads DCP, does optimization, and writes routed DCP.

From the /reference-file/run folder, run the following command.

#make sure you have successfully setup SDx/Vivado environments as previous part shows.
vivado -mode batch -source opt.tcl

Here, the opt.tcl file displays the following:

#DCP files in different stages of Vivado have been written by xocc linker automatically with option "-R2"
open_checkpoint ./_x/link/vivado/vpl/prj/prj.runs/impl_1/pfm_top_wrapper_routed.dcp
#Run post-route physical optimization
phys_opt_design -directive AggressiveExplore
write_checkpoint -force ./_x/link/vivado/routed.dcp

Reuse Checkpoint to Generate Platform File (xclbin)

Next, reuse the routed.dcp checkpoint file generated by the opt.tcl script to generate a new platform file (xclbin). To do this, add the --reuse_impl option to the XOCC command.

xocc -t hw --platform xilinx_u200_xdma_201830_1 -l -o'apply_watermark.hw.xilinx_u200_xdma_201830_1.xclbin' apply_watermark.hw.xilinx_u200_xdma_201830_1.xo --reuse_impl ./_x/link/vivado/routed.dcp

From the message in the console, you can see that the steps to generate the implemented design have been skipped, and the bitstream generation starts.

INFO: [VPL 60-251]   Hardware accelerator integration...
Starting FPGA bitstream generation.

Putting it All Together

The following section summarizes all the steps to control Vivado tools implementation with the XOCC command, optimize design with the Vivado tools, and reuse implemented dcp to generate the platform file. You might use it as a quick reference for commands.

  1. Set up the environment and working directory.

    #setup Xilinx SDx tools, XILINX_SDX and XILINX_VIVADO will be set in this step. source <SDX install path>/settings64.sh. for example:
source /opt/Xilinx/SDx/2019.1/settings64.sh
#Setup runtime. XILINX_XRT will be set in this step
source /opt/xilinx/xrt/setup.sh

  2. Generate the platform file (xclbin) with XOCC commands.

    xocc -t hw --platform xilinx_u200_xdma_201830_1 -g --max_memory_ports apply_watermark -c -k apply_watermark -o'apply_watermark.hw.xilinx_u200_xdma_201830_1.xo' '../src/krnl_watermarking.cl'
xocc -t hw --platform xilinx_u200_xdma_201830_1 -g --sp apply_watermark_1.m_axi_gmem0:DDR[0] --sp apply_watermark_1.m_axi_gmem1:DDR[1] -s --xp vivado_prop:run.my_rm_synth_1.{STEPS.SYNTH_DESIGN.ARGS.FLATTEN_HIERARCHY}={full} --xp vivado_prop:run.impl_1.{STEPS.ROUTE_DESIGN.ARGS.DIRECTIVE}={NoTimingRelaxation} -R2 -l --nk apply_watermark:1:apply_watermark_1 -o'apply_watermark.hw.xilinx_u200_xdma_201830_1.xclbin' apply_watermark.hw.xilinx_u200_xdma_201830_1.xo

  3. Optimize the design with the Vivado tool, and rewrite the routed DCP.

    vivado -mode batch -source opt.tcl

  4. Reuse the routed DCP to generate the platform file (xclbin).

    xocc -t hw --platform xilinx_u200_xdma_201830_1 -l -o'apply_watermark.hw.xilinx_u200_xdma_201830_1.xclbin' apply_watermark.hw.xilinx_u200_xdma_201830_1.xo --reuse_impl ./_x/link/vivado/routed.dcp

  5. This tutorial has provided host code to make it complete to run though various flows. The following commands are references to build the host, and run the application.

    #Generate the host executable.
xcpp -I$XILINX_XRT/include/ -I$XILINX_VIVADO/include/ -Wall -O0 -g -std=c++14 -L$XILINX_XRT/lib/ -lOpenCL -lpthread -lrt -lstdc++ -o 'host' '../src/host.cpp'
#Please set correct XCL_EMULATION_MODE manually if running sw_emu and hw_emu modes
./host apply_watermark.hw.xilinx_u200_xdma_201830_1.xclbin ../src/inputImage.bmp ../src/golden.bmp

Conclusion

This tutorial illustrated how to use the XOCC command --xp option to control Vivado synthesis and implementation, using a simple example to optimize the design with the Vivado tool. It then showed the steps to reuse implemented DCP to generate the platform file (xclbin), skipping the intermediate steps to generate the implemented design.

To run through all flows, the host code and its building commands are also provided for reference.


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