Step 2: Create the Software Components

2021.1 Vitis™ Platform Creation Tutorials See Vitis™ Development Environment on xilinx.com

Due to the boot flow differences between KV260 and base platforms for Xilinx evaluation boards like ZCU104, platform developer needs to prepare one additional DTBO file besides the normal software components for Vitis platforms because application developers needs to add this DTBO file to the application deployment package. The other software components generation flow is similar to the flow described in the ZCU104 tutorial. Since KV260 provides its BSP, we can use the PetaLinux BSP to generate Linux kernel, root file system and boot components, or do more customization based on the BSP.

Step 2: Create the Software Components with PetaLinux

KV260 provides an off-the-shelf boot image and has its enhanced boot sequence. Since the image can boot successfully out of the box, Vitis platform developers can skip some software component preparation steps for Linux booting.

Generating Normal Software Components from the KV260 Starter Kit BSP

1. Check Kria K26 SOM wiki. Download the Starter Kit SOM BSP that matches your tool version under PetaLinux Board Support Package section.

   For example, https://www.xilinx.com/member/forms/download/xef.html?filename=xilinx-k26-starterkit-v2021.1-final.bsp

   Save it to your working directory.

2. Setup PetaLinux environment

   source <petaLinux_tool_install_dir>/settings.sh
   

3. Update PetaLinux eSDK to enable the recipes needed by the Starter Kit SOM BSP.

   petalinux-upgrade -u 'http://petalinux.xilinx.com/sswreleases/rel-v2021/sdkupdate/2021.1_update1/' -p 'aarch64'
   

4. Create PetaLinux with the Starter Kit SOM BSP and the XSA export from step 1.

   petalinux-create --type project -s xilinx-k26-starterkit-v2021.1-final.bsp
   cd xilinx-k26-starterkit-v2021.1
   petalinux-config --get-hw-description=<vivado_design_dir> --silent
   

5. Add XRT to rootfs

   KV260 PetaLinux BSP doesn’t enable XRT because it installs XRT with overlay. To create sysroot for application developer cross compiling, we enable XRT in the rootfs.

   • Run petalinux-config -c rootfs to launch rootfs configuration window.

   • Go to Filesystem packages -> libs -> xrt

   • Enable xrt

   • Press Exit to exit configuration. Press Save to save the configuration.

6. Build PetaLinux and generate SDK

   petalinux-build
   petalinux-build --sdk
   

   The PetaLinux image files and sysroot sdk.sh will be generated in /images/linux directory. We will use them in the next step.

Generate Device Tree Overlay

Since KV260 loads PL after Linux boots up, the PL IP information in the platform needs to be loaded dynamicly as device tree overlay. So one additional requirement for KV260 acceleration platform software is to generate the device tree overlay for the platform PL IPs. This device tree overlay serves two purposes:

1. It needs to have ZOCL node so that XRT driver can be loaded properly

2. It can include any configurations of the PL IP in the platform logic designed in step 1.

The device tree information for PL in your application is loaded after Linux boot together with the PL bitstream. A device tree overlay (DTBO) can be loaded and unloaded in Linux. For more information about DTBO, please refer to https://lkml.org/lkml/2012/11/5/615.

Xilinx provides Device Tree Generator (DTG) to generate device tree from XSA file exported from Vivado. DTG is configurable for which information to be generated. According to our requirement, we will use these two options:

• CONFIG.dt_zocl: Generate ZOCL device tree node for XRT

• CONFIG.dt_overlay: Add overlay properties in dtsi for DTBO generation

Run the following steps to generate DTBO from XSA

1. Install DTG

   git clone https://github.com/Xilinx/device-tree-xlnx
   cd device-tree-xlnx
   git checkout xlnx_rel_v2021.1
   

2. Generate DTS from XSA with XSCT.

   • Launch XSCT

   xsct
   

   • Use XSCT HSI commands to read XSA and generate DTS.

   hsi open_hw_design <design_name.xsa>
   hsi set_repo_path <path to device-tree-xlnx repository>
   hsi create_sw_design device-tree -os device_tree -proc psu_cortexa53_0
   hsi set_property CONFIG.dt_overlay true [hsi::get_os]
   hsi set_property CONFIG.dt_zocl true [hsi::get_os]
   hsi generate_target -dir <desired_dts_filename>
   hsi close_hw_design [hsi current_hw_design]
   

   You can save the hsi commands in a gen_dt.tcl file and use xsct gen_dt.tcl to execute it. If you type these commands in XSCT console directly, you can close XSCT console after the generation completes.

3. Compile the dtsi to dtbo.

   Run the following command in the shell with PetaLinux environment.

   dtc -@ -O dtb -o pl.dtbo pl.dtsi
   

   Note: dtc is device tree compiler. For more info about dtc, please check its man page and source code.

Next Step

Note: Now HW platform and SW platform are all generated. Next we would package the Vitis Platform.

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