port-sparc64/42994: Kernel panic when setting MTU on hme interface. (Netra T1 105 system)

[nimitz%nimitzbrood.com@localhost]

>Number:         42994
>Category:       port-sparc64
>Synopsis:       Kernel panic when setting MTU on hme interface. (Netra T1 105 
>system)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-sparc64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Mar 17 19:55:00 +0000 2010
>Originator:     Mike Hebel
>Release:        Sparc64 5.0.2
>Organization:
>Environment:
mbint# uname -a
NetBSD mbint 5.0.2 NetBSD 5.0.2 (GENERIC) #0: Sat Feb  6 22:11:13 UTC 2010  
builds%b7.netbsd.org@localhost:/home/builds/ab/netbsd-5-0-4
mbint# 
>Description:
mbint# ifconfig hme0 mtu 1450
text_access_fault: pc=0 va=0
panic: kernel fault
Begin traceback...
End traceback...
Frame pointer is at 0xc334b91
Call traceback:
1427130(11, 5, 0, 0, 1857000, 0, c334c61) fp = c334c61
12ed6c0(104, 0, ffff, 16985f9, 12ed400, f, c334d21) fp = c334d21
1430674(1692420, c3357b0, 0, 10f8c0, 0, 104, c334df1) fp = c334df1
1008954(c3357b0, 64, 0, 0, 0, 1afd27ffff0, c334f01) fp = c334f01
13488ec(b74f0f0, 8090697f, b74e890, 5, b74f0f0, 8090697f, c3350e1) fp = c3350e1
1164984(34, 8090697f, b74e890, 8090697f, b74f0f0, 8090697f, c3351a1) fp = 
c3351a1
13427a8(b74f0f0, 8090697f, b74e890, b74f0f0, 8090697f, 0, c335261) fp = c335261
12f4efc(0, 8090697f, b74e890, c0fac00, 1009ed8, 0, c3353c1) fp = c3353c1
142e658(0, c335dc0, c335e00, 1, 212be0, 80000000, c335511) fp = c335511
1008c68(c335ed0, c335f58, 40940b08, 40940b0c, 0, c335dc0, c335621) fp = c335621
108a90(3, 8090697f, ffffffffffffb018, 10f8c0, 0, 22, ffffffffffffa761) fp = 
ffffffffffffa761

dump to dev 7,1 not possible (partition too small?)
rebooting

>How-To-Repeat:
ifconfig hme0 mtu 1450

Problem even occurs if that is set in rc.local to automatically run.
>Fix:
No known fix.  A workaround that I will try is to use pf with pass-all 
configuration to scrub packets for max-mss.