Use the vi editor to open the /boot/EFI/grub2/grub.cfg file, locate linux/vmlinuz-4.1.43-vhulk1708.1.1.aarch64 root=/, and add the following information:
console=tty0 console=ttyAMA0,115200
To enable user root to log in to the BMS through the serial port, check whether ttyAMA0 is contained in the security configuration file /etc/securetty. If not, add it.