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

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

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
--