kern/43226: Panic when serial console reboots (?)

[dmz%pro.wp.pl@localhost]

>Number:         43226
>Category:       kern
>Synopsis:       Panic when serial console reboots (?)
>Confidential:   no
>Severity:       non-critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Apr 29 14:20:00 +0000 2010
>Originator:     Dominik Zaczkowski
>Release:        NetBSD5
>Organization:
>Environment:
NetBSD kraina-oz.ath.cx 5.0_STABLE NetBSD 5.0_STABLE (GENERIC) #0: Wed Jul 29 
20:45:55 CEST 2009  
root@kraina-oz:/usr/obj/obj/usr/obj/netbsd-5/src/sys/arch/i386/compile/GENERIC 
i386

>Description:
I use NetBSD box as router and file server for my lan, recently I connected it 
by com to one of my WinXP pcs and to my big surprise it panics every time I 
reboot the WinXP pc!

For NetBSD, I boot it via grub with multiboot, here is menu.lst fragment:

root (hd0,0,a)
kernel /gnetbsd root=wd0a console=com
boot

Also from unknown to me reason it doesn't save coredump properly, here is what 
bt in ddb says:

breakpoint(7,0,cab035b0,c10b8000,c10b9000,800,9099f944,0,0,8) at netbsd:breakpoi
nt+0x4
comintr(cab034a4,ca35fcc8,0,0,0,0,0,0,0,0) at netbsd:comintr+0xed
DDB lost frame for netbsd:Xintr_ioapic_edge9+0xa9, trying 0xca7eef74
Xintr_ioapic_edge9() at netbsd:Xintr_ioapic_edge9+0xa9
--- interrupt ---
--- switch to interrupt stack ---
x86_stihlt(0,0,c0389409,ca367c80,c03845c3,ca367c80,0,c01002e1,ca367c80,0) at net
bsd:x86_stihlt+0x5
idle_loop(ca367c80,0,c01002cd,0,c01002cd,0,0,0,0,0) at netbsd:idle_loop+0x95

>How-To-Repeat:
Restart the com console.
>Fix:
Do not use com for console.