Xen console detection/selection

[Erik Fair <fair%netbsd.org@localhost>]

The other thing about NetBSD and Xen that has me a bit confused is Xen console 
detection/selection for systems without RS-232 (COM0) serial ports, e.g. all 
you have is built-in graphics ("vga") and USB ports for 
keyboard+mouse+whatever. I've got an HP Proliant Microserver N40L which fits 
that description.

What I observe is that when the Xen hypervisor is started, console output 
ceases entirely until the getty prompt from the dom0 appears. One can recover 
the dom0 boot messages from dmesg, but that's it. What's going on here?

My /boot.cfg reads as follows:

menu=Boot Xen (vga):load /netbsd.dom0 console=com0;multiboot /xen.gz 
dom0_mem=256M console=vga
#
menu=Boot Xen (vga, single user):load /netbsd.dom0 -s console=com0;multiboot 
/xen.gz dom0_mem=256M console=vga
#
menu=Boot normally:rndseed /var/db/entropy-file;boot netbsd
#
menu=Boot single user:rndseed /var/db/entropy-file;boot netbsd -s
#
menu=Disable ACPI:rndseed /var/db/entropy-file;boot netbsd -2
#
menu=Disable ACPI and SMP:rndseed /var/db/entropy-file;boot netbsd -12
#
menu=Drop to boot prompt:prompt
#
default=1
timeout=10
clear=1


You will note that the dom0 is told to use "com0" (which is presumably being 
provided under emulation by the Xen hypervisor); that's what worked for me to 
get anything to work at all, and I was just guessing that a VM would have to do 
something like this.

What's the recommended method?

        curious,

        Erik <fair%netbsd.org@localhost>