The br23uboot100 configuration defines the firmware initialization sequence for Baidu’s Kunlun AI processor series. Unlike standard embedded Linux devices, AI accelerators require a specialized boot flow to handle massive DDR address spaces and specific AI-core power domains. This analysis details the porting of U-Boot 2020.04 (or similar baseline) to the Kunlun BR100 architecture, focusing on the verification of the SPL (Secondary Program Loader) handoff, DDR controller initialization, and the device tree overlay mechanism used for hardware discovery.
The BR100 does not boot directly into a full operating system. It utilizes a multi-stage initialization process defined within the br23uboot100 configuration. br23uboot100 verified
Use the mkimage tool to package and sign the image: The -r flag marks the image as requiring verification
tools/mkimage -f br23.its -k keys -K u-boot.dtb -r u-boot-fit.img
The -r flag marks the image as requiring verification. The public key is embedded into U-Boot's device tree. In the menuconfig, ensure the following are enabled:
The identifier br23 typically refers to a specific board revision or SoC variant ID within the Kunlun family. The uboot100 suggests versioning or a specific internal release tag.
Navigate to the U-Boot source directory and configure it for your BR23 board. Look for a config file named br23_defconfig or similar.
make br23_defconfig
make menuconfig
In the menuconfig, ensure the following are enabled: