kern/39237: Xen3 custom kernel enters debugger when destroying a strangely numbered network interface

[randolf+netbsd.org%inter-corporate.com@localhost]

>Number:         39237
>Category:       kern
>Synopsis:       Xen3 custom kernel enters debugger when destroying a strangely 
>numbered network interface
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jul 28 06:45:00 +0000 2008
>Originator:     Randolf Richardson
>Release:        4.99.70
>Organization:
Inter-Corporate Computer & Network Services, Inc.
>Environment:
NetBSD netbsd.test.lumbercartel.ca 4.99.70 NetBSD 4.99.70 (XEN3_DOM0) #0: Mon 
Jul 21 04:34:08 PDT 2008  
builds@wb38:/home/builds/ab/HEAD/i386/200807210002Z-obj/home/builds/ab/HEAD/src/sys/arch/i386/compile/XEN3_DOM0
 i386

>Description:
Xen3's tap interface, when destroyed by ifconfig (and possibly also 
"/etc/rc.d/network restart" -- sorry I haven't tried this), launches the system 
into the debugger.

>How-To-Repeat:
After starting a DomU (this one runs Windows XP Professional using HVM support 
and has 1 GB of RAM assigned to it; the hard drive is actually just a 20 GB 
file on the NetBSD volume which uses FFSv2 with softdep), a tap0 network 
interface is created.

If I type "ifconfig tap0 destroy" at the shell prompt (logged in as root), the 
server enters the debugger.

>Fix:
Don't type "ifconfig tap0 destroy" when Xen3 created tap0 and is running a 
virtual machine that depends on it.