You have two ways to choose which kernel and system to boot,

1. At PMON command line,for instance, you want to load the kernel in hda1’s boot directory named vmlinux and the system in hda1,use following commands :

load /dev/fs/ext2@wd0/boot/vmlinux 

g console=tty root=/dev/hda1 

2. Edit the file named boot.cfg(like menu.lst in grub) in hda1’s boot directory.If the file does not exist ,create one.

Typically ,the content of the file like the following:

timeout 3

default 0

showmenu 1

title Debian Linux for Loongson

kernel /dev/fs/ext2@wd0a/boot/vmlinux

args console=tty root=/dev/hda1

If you have installed another OS on hda2 and that kernel named vmlinux2,you can edit the boot.cfg to add one entry in bootmenu .Add the following three lines to enable it:

title another Linux for Loongson

kernel /dev/fs/ext2@wd0b/boot/vmlinux2

args console=tty root=/dev/hda2

NOTE: if you don’t see bootmenu when booting ,please make sure your machine has boot.cfg file in hda1’s boot directory and your PMON enable to show the bootmenu.You can goto PMON command line ,and input ‘env’ command to list all environment variables .If there is no variable named ShowBootMenu ,use ‘set ShowBootMenu yes’ to create the variable.