Hi! The original .bin file comes from Rockchip's repositories: It is later customized to use UART9 with [

ddrbin_tool.py

]() using these parameters:

start tag=0x12345678

uart id=9
uart iomux=0
uart baudrate=115200

end

That customization is what produces the

_uart9_115200_

variant, which uses the correct serial output for the DDR initialization messages (and leaves it initialized for U-Boot).