Booting grml64-medium_0.1.iso on an HP Proliant DL380G5 machine
with virtual serial port (acting as a terminal connected to COM2 @ 115200),
using this command line: "grml console=tty 1console=ttyS1,115200n8", makes
kernel and boot log be displayed on ttyS1, up to the point where
mgetty is started on ttyS1, when it stops working.

A few points:
1) mgetty doesn't work on this machine. normal getty does.
   To make the serial console work, I had to comment out the
   mgetty line for ttyS1, uncomment the default debian's inittab
   line (which also works fine on machines with physical serial
   ports) and fix the speed:

T1:23:respawn:/sbin/getty -L ttyS1 115200 vt100

   then init q, kill off mgetty and bash on ttyS1.  getty appeared.
   FWIW, I haven't needed anything other than default getty to make
   serial console (via null-modem cable or HP's virtual serial port),
   work since sarge or woody (and I haven't messed with serial ports
   before that).

2) It would be nice if any and all devices in console=...
   parameters were automatically added to /etc/securetty (/dev/ttyS1
   is NOT present by default), so that root may log in from there.

   Doing http://bts.grml.org/grml/issue474 (grml-quickconfig
   to appear on serial if the user booted w/ serial console) could be
   an alternative or a nice addition to that.  Since the kernel gives
   the last console=... as userspace (init) stdint/stdout/stderr, and
   init dumps all its output there, it would be least surprising to
   make grml-quickconfig appear on that very same tty.  That's probably
   what the user is looking at.

If these are implemented, the user won't have to do anything on the
tty1 VGA console to boot up to a usable grml enviroment on serial.