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If the board name field is not correct, the Certified Ubuntu on Xilinx Devices image will not boot properly. The Certified Ubuntu release uses this data during its initial boot phase (the ImgSel tool) documented by Xilinx here: Booting Certified Ubuntu 20.04 LTS for Xilinx Devices . The ImgSel tool reads the board name and then uses this information to boot the correct BOOT.BIN file.
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The core of the Certified Ubuntu for Xilinx Devices boot process on ZCU10x boards is the Image Selector tool. This utility performs the initial boot of the board, reads board-identifying information from the attached EEPROM, and then reboots into a customized set of boot collateral for the specific board it is running on. For more detail on this process, see the Booting Certified Ubuntu 20.04 LTS for Xilinx Devices page.This is what allows the same Certified Ubuntu for Xilinx Devices SD card image to boot on multiple boards. Typically, there is no need to modify this code. If a user determines that they would like to modify the way that Image Selector operates, it can be rebuilt inside the Vitis environment. The source code of Image Selector is part of the Xilinx embeddedsw repository on the Xilinx GitHub.
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Minimum Processing System (PS) configuration:
https://github.com/Xilinx/embeddedsw/blob/master/lib/sw_apps/imgsel/src/psu_init.c#L1045
Minimum Board Support configuration:
https://github.com/Xilinx/embeddedsw/blob/master/lib/sw_apps/imgsel/src/xis_singleimage.c#L50
Using a Custom Device Tree
To temporarily override the dtb without modifying the fit image (Kria) or bootxxxx.bin (zcu10x), you can create a new dtb named "user-override.dtb". Copy user-override.dtb to the FAT partition and reboot. If user-override.dtb is found on the FAT partition by U-boot, it will use this dtb instead of the board-specific dtb found in the FIT image when Linux is started.
Understanding the Configuring flash-kernel Prompts When Updating the Linux Kernel
When updating the Linux kernel via packages available in the Ubuntu package feed, the following prompt may appear:
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In general, it is safe to choose either the local version or the maintainer’s version. This message is an artifact how the Linux kernel packages are configured for the Certified Ubuntu image. Typically, the Ubuntu version of the Linux kernel includes both the splash and quietcommand line arguments. The splash argument is typically used in desktop Linux distributions and instructs the kernel to display a splash screen (eg, a screen displaying the distribution's logo) if one is available. The quiet argument puts the kernel into non-verbose mode. Omitting this option will produce much more output on the terminal during Linux kernel boot. In most Linux distributions (including Ubuntu), the quiet argument is used to produce a more aesthetically pleasing boot experience. The AMD-Xilinx Certified Ubuntu image omits the quiet argument in order to produce more debug messages that are useful when prototyping. This change in the default boot arguments is applied using a meta-package overlay. This overlay causes a mis-match in the kernel package configuration when updating it via normal package management methods.
When updating the kernel, the options presented correspond to:
install the package maintainer's version-- This option will add the default "quiet splash" options back to the Linux kernel command linekeep the local version currently installed-- This option will keep the AMD-Xilinx configuration which omits thequietoption.