Dear all :
After Referring to the Documentation/serial-console.txt in the kernel
package, I found how to enable this.
1.edit the /etc/grub.conf, find the line
2. add “console=ttyS0,38400 console=tty0” at the tail. Of course, you
need a comport first.
3. grub-install /dev/hda
The above steps are used for watching boot message, or you can ignore
these steps if you don’t need to see boot message
4.add “S1:23:respawn:/sbin/agetty -L ttyS0 38400 vt100” at the tail of
5.add “ttyS0” at the tail of /etc/securetty, or you can’t login with root
6. passwd -d root , If you want the root login with no password
7. reboot and watch the serial port with your favorite terminal program.
Note: Test in Redhat9