[Qemu-discuss] How to commucation by serial ports between host and target?

[Parmenides]

HI,

    When debugging the linux kernel with kgdb, it is necessary to
commucation between the host and the target. I started the qemu with:

              qemu -m 64M -kernel arch/x86/boot/bzImage -initrd
~/image.cpio.gz  -net nic -net tap,ifname=tap0 -vnc :1 -serial
/dev/ttyS0

and think the target will redirect its serial port to the host's
/dev/ttyS0. I set the serial ports

              stty ispeed 115200 ospeed 115200 -F /dev/ttyS0

in the target, and

              stty ispeed 115200 ospeed 115200 -F /dev/ttyS0

Then,

              cat /dev/ttyS0

in the target, and

              echo hello > /dev/ttyS0

But, it seems that the commucation does not work. How to make the host
and the target commucation by their serial ports? Thx.