command line – 22.04 server U-Boot issue on a Raspberry PI

all,

I’ve installed on an old Raspberry PI 3B a copy of the latest Ubuntu available for this. The reason I did that is because I wanted a viable Linux system on a PI that used U-Boot. The ultimate goal is to demonstrate using U-Boot in an interactive way.

The problem is this: The console port shows no U-Boot messages or activity during boot. U-Boot is certainly present in /boot/ as bin files for various PIs, but the serial line’s first message is from the already loaded kernel.

Can I force U-Boot into the boot chain or, if it is already there, get it to communicate with the console serial line during its activity?