 2021.1 Vitis™ Application Acceleration Development Flow TutorialsSee 2020.1 Vitis Application Acceleration Development Flow Tutorials |
Bottom-up RTL Kernel Flow with Vitis for Acceleration¶
RTL design is a traditional and important hardware accelerator development methodology for FPGA. RTL modules provide excellent flexibility and efficiency, while the design process is a timing consuming and error-prone process. The Xilinx® Vitis™ unified software platform provides a mature and proven RTL kernel design methodology. With Vitis and the included Vivado® Design Suite, you can focus on your core accelerating module, instead of spending a lot of time on integration, host-FPGA communication, DMA, and other supporting tasks.
About This Tutorial¶
This tutorial introduces a bottom-up Vitis-based RTL kernel construct and wrap-up process, as well as the host-kernel interaction with Xilinx Runtime library (XRT). All the steps in this tutorial use the command-line interface, except those needed to view waveform or system diagram.
This tutorial uses an example design to illustrate the relevant concept and steps. The following image shows the block diagram of this design. It is a simple AES accelerator design and comprises two kernels, krnl_aes and krnl_cbc. The krnl_aes kernel is the core AES computation core with AXI streams slave and master ports. The krnl_cbc kernel handles the host-kernel data exchange, and the implementation of AES-ECB and AES-CBD modes along with the krnl_aes module.
Alveo™ Data Center accelerator cards are the target platform for this tutorial, which describes the following tasks:
Packing RTL design to Vitis-compliant RTL kernel with command line interface
Using MMCM/PLL in the RTL kernel
Using Vivado XSIM to simulate the design
Using Xilinx AXI VIP to verify the RTL design with AXI interface
Using three RTL kernel control modes with XRT:
ap_ctrl_none,ap_ctrl_hsandap_ctrl_chain.Host programming for the RTL kernel with XRT Native API
Using Vitis hardware emulation to get an insight look of the RTL kernel operation
Note: This is not a detailed tools usage guideline, so only basic ideas and steps are shown. You will need to refer to other documents for details.
Device and Software Requirements¶
The designs have been verified with the following software/hardware environment and tool chain versions:
Operating Systems:
Redhat/CentOS 7 (See Additional Requiements for RedHat/CentOS)
Ubuntu 18.04/20.04 (See Additional Requiements for Ubuntu)
Perl package installed for Verilog simulation (required)
OpenSSL library installed for hardware output validate (required)
GCC 7
Vitis: 2021.1
XRT: 2.11.634
Hardware and Platform for your Alveo card (you need both the deployment and development platforms):
Alveo U200: xilinx_u200_xdma_201830_2
Alveo U250: xilinx_u250_xdma_201830_2
Alveo U50: xilinx_u50_gen3x16_xdma_201920_3
Alveo U280: xilinx_u280_xdma_201920_3
Additional Requirements for RedHat/CentOS¶
If you are using RedHat/CentOS 7, the default installed GCC version is 4.x.x. You must use the following command to install and switch to GCC 7 before compiling the host program.
sudo yum install centos-release-scl
sudo yum install devtoolset-7-gcc-c++
scl enable devtoolset-7 bash
To install OpenSSL library for CentOS/Redhat, use:
sudo yum install openssl-devel
Additional Requirements for Ubuntu¶
To install OpenSSL library for Ubuntu, use:
sudo apt install libssl-dev
Tutorial Contents¶
This tutorial is separated into three parts, and are intended to be used in order.
This part gives a brief introduction to AES algorithm and the core RTL module for AES acceleration. The RTL AES module uses native Verilog interface. A simple Verilog testbench is provided to verify the function of the RTL module.
This part packs the RTL module described in the first part into a Vitis kernel called krnl_aes, which can be integrated into Vitis. The krnl_aes kernel has four internal AES pipelines and includes AXI control slave and AXI stream master/slave ports.
The krn_aes kernel has a mix control model of ap_ctrl_none and ap_ctrl_hs.
An MMCM IP is used in this kernel to generate required core clock, while the AXI interface uses the standard platform clock. A simple Verilog testbench with Xilinx AXI VIPs are provided to verify the function of the kernel.
In this part, we also integrate the krnl_aes kernel with a few HLS kernels to generate a usable XCLBIN file. A host test program with XRT native API is used to test the function of the krnl_aes kernel.
This part introduces a new RTL kernel called krnl_cbc, which has AXI master interfaces as well as AXI stream interfaces. This kernel will be connected with the krnl_aes kernel to implement AES-ECB and AES-CBC mode encryption/decryption functions.
The krnl_cbc kernel supports ap_ctrl_chain control models. You can study and compare the behavior and performance differences between ap_ctrl_chain and ap_ctrl_hs model usint the provided AXI VIP based testbench, hardware emulation, and host program.
The directory structure and brief explanations of the design repository are as follows.
├── aes # Directory for first part: aes
│ ├── rtl/ # Verilog sources
│ ├── tbench/ # Verilog/SystemVerilog testbench files
│ ├── filelist_aes.f # file list file for xsim simulation
│ ├── Makefile # Makefile for all operation
│ ├── runsim_aes_xsim.sh # shell script to run the simulation with xsim
│ └── xsim.tcl # xsim tcl script for simulation
│
├── common # common resources
│ └── plain_gen.pl # Perl script to generate input data for RTL simulation
│
├── doc # documents
│
├── krnl_aes # Directory for second part: krnl_aes
│ ├── hls # HLS sources
│ ├── host/ # Host test program
│ ├── rtl/ # Verilog sources
│ ├── tbench/ # Verilog/SystemVerilog testbench files
│ ├── filelist_krnl_cbc.f # xsim simulation command file
│ ├── gen_ip.tcl # Vivado tcl script to generate required IPs
│ ├── krnl_aes_test.cfg # Vitis v++ link config file
│ ├── krnl_aes_test.xdc # Vitis v++ link constraint
│ ├── krnl_aes.xdc # constraint for kernel krnl_aes
│ ├── Makefile # Makefile for all operation
│ ├── pack_kernel.tcl # Vivado tcl script to pack the kernel
│ ├── runsim_krnl_aes_xsim.sh # shell script to run the simulation with xsim
│ ├── setup_emu.sh # shell script to enable/disable hw_emu emulation mode
│ └── xrt.ini # XRT config file for emulation/profiling
│
├── krnl_cbc # Directory for third pard: krnl_cbc
│ ├── host/ # Host test program
│ ├── rtl/ # Verilog sources
│ ├── tbench/ # Verilog/SystemVerilog testbench files
│ ├── filelist_krnl_cbc.f # xsim simulation command file
│ ├── gen_ip.tcl # Vivado tcl script to generate required IPs
│ ├── krnl_cbc_test.cfg # Vitis v++ link config file
│ ├── krnl_cbc_test.xdc # Vitis v++ link constraint
│ ├── Makefile # Makefile for all operation
│ ├── pack_kernel.tcl # Vivado tcl script to pack the kernel
│ ├── runsim_krnl_cbc_xsim.sh # shell script to run the simulation with xsim
│ ├── setup_emu.sh # shell script to enable/disable hw_emu emulation mode
│ ├── xrt.ini # XRT config file for emulation/profiling
│ └── xsim.tcl # xsim tcl script to set hw_emu simulation options
│
└── README.md