At the U-Boot prompt, you set environment variables that control the DTB loading:
Maps hardware signals to the CPU’s interrupt controller. dtb firmware
This is the tool that converts the human-readable .dts into the binary .dtb that the bootloader (like U-Boot) can actually read. Why is DTB Firmware Important? At the U-Boot prompt, you set environment variables
Lena pointed at the main computer core—a ruggedized ARM board no bigger than a deck of cards. “This chip doesn’t know what hardware it’s attached to. The GPS, the pumps, the rudder sensor—none of it. The DTB is its map.” At the U-Boot prompt