port-amd64/45242: System panics with 3C905C ethernet cards

[andrews%sdf.lonestar.org@localhost]

>Number:         45242
>Category:       port-amd64
>Synopsis:       System panics with 3C905C ethernet cards
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Aug 12 00:55:00 +0000 2011
>Originator:     Andrew Smallshaw
>Release:        NetBSD 5.1 release
>Organization:
>Environment:
NetBSD n1c 5.1 NetBSD 5.1 (GENERIC) #0: Sat Nov  6 13:19:33 UTC 2010  
builds%b6.netbsd.org@localhost:/home/builds/ab/netbsd-5-1-RELEASE/amd64/201011061943Z-obj/home/builds/ab/netbsd-5-1-RELEASE/src/sys/arch/amd64/compile/GENERIC
 amd64

>Description:
Background: this was a machine running basically OK but with a few niggles that 
were blamed on the onboard nfe ethernet.  This was disabled an a couple of 3Com 
3C905Cs dropped in in its place.  Only one adapter is configured at this stage 
and problems persist even if the second adapter is removed.  Cards work fine on 
a machine running i386 5.0.2.

When left idle system appears relatively stable but in actual use panics are 
very common - perhaps after half an hour of use.  To put this in context the 
system is accessed exclusively with tightvnc so that probably equates to 
hitting the network more than is average.  If an attempt is made to boot under 
XEN the system invariably panics before booting is complete.

Console message on panic, dmesg for the machine and complete transcript of 
attempt to boot under XEN may be found at 
http://andrews.freeshell.org/mail/20110812.netbsd-bug/  Panic dump (155MB) 
available on request.
>How-To-Repeat:
No systematic nature identified save for details already given above.
>Fix: