Re: kern/46199: 6.0_BETA. "qemu -net tap" + bridge(4). Network problems in guests.

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

The following reply was made to PR kern/46199; it has been noted by GNATS.

From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%NetBSD.org@localhost, gnats-admin%NetBSD.org@localhost, 
netbsd-bugs%NetBSD.org@localhost
Subject: Re: kern/46199: 6.0_BETA. "qemu -net tap" + bridge(4). Network
 problems in guests.
Date: Thu, 15 Mar 2012 13:05:38 +0100

 On Thu, Mar 15, 2012 at 11:30:00AM +0000, cheusov%tut.by@localhost wrote:
 > For testing purposes I use qemu with tap networking.
 > 
 >     /etc/rc.conf:
 >         net_interfaces='fxp0 bridge0'
 > 
 >     /etc/ifconfig.bridge0:
 >         !ifconfig tap0 create up
 >         !ifconfig tap1 create up
 >         !ifconfig tap2 create up
 >         !ifconfig tap3 create up
 >         !brconfig bridge0 add fxp0 add tap0 add tap1 add tap2 add tap3
 > 
 > Qemu guests are run with the following scripts:
 > 
 >    qemu -no-acpi \
 >        -drive file=/srv/qemu/openbsd.img,index=0,media=disk,cache=none \
 >        -m 192 \
 >        -net nic,model=ne2k_pci,macaddr=00:06:80:A3:85:CE \
 >        -net tap,fd=3 -boot c "$@" 3<>/dev/tap1
 > 
 >    qemu -no-acpi \
 >        -hda /srv/qemu/dfly.img \
 >        -m 192 \
 >        -net nic,model=ne2k_pci,macaddr=02:07:83:A8:81:FF \
 >        -net tap,fd=3 \
 >        -boot c "$@" 3<>/dev/tap3
 > 
 > I started them one-by-one and they started sucessfully for some time
 > and are becomes visible in my LAN.
 > However, after some time of uptime the network in guests(s) gisappeared.
 > 
 >     0 cheusov>ssh vm-openbsd uptime
 >     12:54PM  up 19 mins, 0 users, load averages: 0.07, 0.10, 0.08
 >     0 cheusov>ssh vm-dfly uptime
 >     ssh: connect to host vm-dfly port 22: Connection timed out
 >     255 cheusov>ssh vm-openbsd uptime
 >      1:02PM  up 26 mins, 0 users, load averages: 0.15, 0.11, 0.09
 >     0 cheusov>
 > 
 > I don't know is this a bug in the kernel or in qemu.
 > Restarting guest OS doesn't help.
 > 
 > But the following solves the problem.
 >    ifconfig tap3 destroy
 >    ifconfig tap3 create up
 >    brconfig bridge0 add tap3
 >    qemu ... 3<>/dev/tap3
 
 would a down/up on tap3 fix the issue ?
 Also, displaying the interface queues could help (maybe netstat -id)
 
 -- 
 Manuel Bouyer <bouyer%antioche.eu.org@localhost>
      NetBSD: 26 ans d'experience feront toujours la difference
 --