The U-Boot acts as a secondary boot loader. After the FSBL handoff, the U-Boot loads Linux on the Arm® Cortex-A53 APU. After FSBL, the U-Boot configures the rest of the peripherals in the processing system based on board configuration. U-Boot can fetch images from different memory sources such as eMMC, SATA, TFTP, SD, and QSPI. For this example, U-Boot and all other images are loaded from the SD card. Therefore, for this example, the board will be set to SD-boot mode.
U-Boot can be configured and built using the PetaLinux tool flow. For this example, you can use the U-Boot image that you created in Building Linux Software for PS Subsystems.