I'm having some hard time here, and right now im totally out of ideas, I've got a bPi M3 set up with Raspbian OS and I'm trying to boot from a 2.5" HDD.
I've edited the cmdline.txt in the boot particion to boot from dev/sda1 (which is the HDD in this case) and /etc/fstab accordingly, but it seems like it doesnt really matter, because it'll boot from the SD card either way.
It seems like the OS is ignoring the boot particion and tries to boot from somewhere else, pre-defined somewhere-else. I've tried to set an incorrect path in /boot/cmdline.txt and even in that case it boots up correctly. So I assume it tries to fetch booting related information from somewhere else.
Am I correct about this?