From kwhite@infox.csi.uottawa.ca  Thu Jul  3 09:40:18 1997
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Date: Thu, 3 Jul 1997 12:41:21 -0400 (EDT)
From: kwhite@site.uottawa.ca
Reply-To: kwhite@site.uottawa.ca
To: FreeBSD-gnats-submit@freebsd.org
Subject: Fatal double fault using vn device
X-Send-Pr-Version: 3.2

>Number:         4022
>Category:       kern
>Synopsis:       Fatal double fault using vn device
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Jul  3 09:50:00 PDT 1997
>Closed-Date:    Mon May 4 03:44:20 PDT 1998
>Last-Modified:  Mon May  4 03:44:44 PDT 1998
>Originator:     Keith White
>Release:        FreeBSD 2.1-STABLE i386
>Organization:
SITE, University of Ottawa
>Environment:

uname -a :
FreeBSD infox 2.1.5-RELEASE FreeBSD 2.1.5-RELEASE #6: Wed Jul  2 15:46:33 EDT 1997     kwhite@infox:/usr/src/sys/compile/infox  i386

The machine is a 486DX-33 EISA.  lsdev -c gives:

# This listing automatically generated by lsdev(1)
# CPU cpu0
controller scbus0
controller eisa0
controller isa0
sc0	at isa? tty port 0x60 irq 1
ed0	at isa? net port 0x300 irq 5 iomem 0xd8000 iosiz 8192
sio0	at isa? tty port 0x3f8 irq 4
sio1	at isa? tty port 0x2f8 irq 3
lpt0	at isa? tty port 0x378 irq 7
lpt1	at isa? tty port ?
pca0	at isa? tty port 0x40
fdc0	at isa? bio port 0x3f0 irq 6 drq 2
fd0 at fdc0 drive 0
fd1 at fdc0 drive 1
wdc0	at isa? port 0x1f0 irq 14
aha0	at isa? bio port 0x330 irq 11 drq 5
sd0 at SCSI bus 0:0:0
st0 at SCSI bus 0:1:0
npx0	at isa? port 0xf0

>Description:

I'm trying to use a vn device to contain a root filesystem in a
UFS/MSDOS/NFS file.  When I use tar or dump/restore to create the file
system, the kernel panics with a "Fatal double fault" or simply reboots
with no message.  If I build a kernel with DDB support, the trace is
	_Debugger()
	_panic()
	_trapwrite(0,0,0,0,0) at _trapwrite

I get the same problem with FreeBSD 2.1.5 and FreeBSD 2.2.2 

>How-To-Repeat:

IMAGE=/local/tmp/fbsdroot
SIZE=160

dd if=/dev/zero bs=100k count=$SIZE of=$IMAGE
vnconfig -cv /dev/vn0 $IMAGE
newfs -T mta3230 -u $SIZE -t 10 -c 10 \
	-s `ls -l $IMAGE | awk '{print $5/512}'` /dev/rvn0
mount /dev/vn0 /mnt
cat .../2.2.2/bin/bin.?? | tar --unlink -xvpzf - -C /mnt

>Fix:
	No fix known.

I can get further with the extraction if I run a "dd" in the background:
	dd if=$IMAGE of=/dev/null bs=10k &
>Release-Note:
>Audit-Trail:
State-Changed-From-To: open->closed 
State-Changed-By: phk 
State-Changed-When: Mon May 4 03:44:20 PDT 1998 
State-Changed-Why:  
A lot of problems with VN has been fixed since. 
>Unformatted:
