Building a platform for further exploration in hardware

In order to facilitate additional exploration of the MLIR AIE tools in hardware, a basic platform can be built to run the generated programs on an AI Engine-enabled device + board (vck190). Such a platform also provides the necessary sysroot required to cross-compile MLIR AIE code for simulation, such as for the tutorials.

Building a platform to explore MLIR AIE generated designs consists of building the Vitis hardware design and the Petalinux kernel and linux filesystem to run it. The Petalinux filesystem can be targeted by the MLIR AIE python build scripts (aiecc.py) when cross-compiling the host code to be run on the board. Even without a physical board, we can still build the platform and associated sysroot to support cross-compilation. Once a physical board is present, we can complete the steps to run the AIE designs on a live board.

Prerequisites for building the platform and sysroot

Xilinx Vitis 2021.2
Petalinux 2021.2

See the notes in Getting Started for the additional packages that will be needed to successfully install Vitis on a bare-bones Ubuntu machine. Additionally to those packages, building the sysroot on Ubuntu will also require:

  • libpthread-stubs0-dev
  • graphviz (provides dot)

The ‘platform’ sub-directory contains the necessary Makefile and build scripts to simplify the build process. The same system requirements to run Vitis and Petalinux will be required for the platform build flow so please refer to those software tool requirements.

vck190 ‘bare’ platform

The vck190 ‘bare’ platform is a nearly empty design that enables the necessary NoC connections for any AIE-compiled design. In addition to configuring the CIPS, AI Engines and NoC, it contains minimal PL components sush as clock, reset and a BRAM (64kB) scratchpad attached to the NoC.

Platform and sysroot build steps

To start the build, first set up your Vitis and PetaLinux environments:

source <Vitis 2021.2 Install Path>/settings64.sh
source <PetaLinux 2021.2 Install Path>/settings.sh

Then, run the following:

cd platforms/vck190_bare_prod
make all

The Makefile will first call a tcl script to build the Vivado design and generate an .xsa file. Then, a Makefile in the petalinux subdirectory generates the petalinux linux kernel, a ramdisk rootfs, and boot files. Lastly, petalinux is called to generate a sysroot which can be used during MLIR AIE cross-compilation.

Prerequisites for running designs on a physical board

SD card (16 GB+)
vck190 board + usb-c to usb cable + ethernet cable

Board setup steps

After the build is complete, format an SD card (16 GB+) in fat32 format and copy the files from the linux subdirectory onto the SD card.

cp -r platforms/vck190_bare/petalinux/images/linux/* <SD card directory>

Put the sd card into the micro sd slot to boot up the Versal device (top of the board), connect the board usb-c connector to your host machine and turn on the board. You should run a program like TeraTerm and configure it as a serial port (115200 baud, 8b data, no parity, 1b stop, no flow control). The serial port for Versal is usually the first port but may vary in your setup.

You should then be able to copy binaries compiled by the MLIR AIE tools to test on the board. This is done by first copying the files onto the sd card directly while the card is inserted/ mounted in your host machine. Then reinsert the sd card back into the board. The board boots up as root and the rootfs is running in a ramdisk so no files are saved except those in the primary sd partition.

Run binaries steps

To run binaries on the board, do the following in your serial port terminal after bootup:

cd /mnt/sd-mmcblk0p1
export XILINX_XRT=/usr
<executable>

Another option for copying files onto the card from your host is via an ethernet connection. If the board is connected to your host machine through an ethernet switch, you should be able to scp files to the board. In addition to root, there is a username/password account for petalinux/petalinux. From the host, you can copy files as follows:

scp <your files> petalinux@192.168.0.101:/home/petalinux/.
petalinux <-- password for scp

Then on the board, run:

cp /home/petalinux/<your files> /mnt/sd-mmcblk0p1/.

and run on the board as usual.


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