[Qemu-devel] multiple VM on one tap device

[Qemu-devel] multiple VM on one tap device

[Kирилл Паленов]

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Hello all.

Is it possible run several VM connected with one tap device?
I tried to run two VM with allready exist tap0 but when I started second
I've got message: "warning: could not configure /dev/net/tun: no virtual
network emulation Could not initialize device 'tap' ".

I did following under root:

-bash-3.00# tunctl -b -t tap0
-bash-3.00# ifconfig tap0 192.168.4.1 netmask 255.255.255.0 up
-bash-3.00# ifconfig tap0
tap0      Link encap:Ethernet  HWaddr 00:FF:A1:81:05:B0
          inet addr:192.168.4.1  Bcast:192.168.4.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

Then started VM with following parameters:

1. -net nic,macaddr=00:1a:4b:34:74:43 -net
tap,vlan=0,ifname=tap0,host=sv3,script=no
2. -net nic,macaddr=00:1a:4b:34:74:44 -net
tap,vlan=0,ifname=tap0,host=sv4,script=no

I did it under linux kernel 2.6.23.9.

What does it mean fd in -net tap,fd ?  File discriptor of /dev/net/tun  or
tap device.

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