[U-Boot] difference between ft_board_setup() and ft_system_setup()

hi,

i've seen today that there is some kconfig option to switch on CONFIG_OF_SYSTEM_SETUP, which turns on calling some ft_system_setup() function before booting the OS.

In the days before this my meaning was to implement all things which i have to modify dynamically within ft_board_setup().

What is the purpose of ft_system_setup, which thing should be implemented here and which things should stay in ft_board_setup?

many thanks and best regards, Hannes