Re: [Qemu-discuss] Tap Devices

[Mike Lovell]

On 11/28/2012 06:43 AM, Frans de Boer wrote:
> I would like to use OpenvSwitch + Qemu together with opensuse 12.2. I 
> have OpenvSwitch and Qemu working correctly...as user root!
>
> The problem is neither of them above, rather it's the creation of tap 
> devices from Userspace. I see all kinds of possible solutions, some 
> very dated some newer, but nothing yet I believe will work from 
> Userspace only.
>
> I have used VDE before, but had to disable the Firewall to have 
> Internet access from the quests. OpenvSwitch is slightly faster then 
> VDE so I would like to give that a try.
>
> Any suggestions regarding the creation of tap devices from Userspace 
> are welcome.

i don't know what version of qemu is distributed with opensuse 12.2 so i 
don't know if this will help. in the 1.1 release, there was support 
added to use a helper program to configure the tap devices. the program 
included with the qemu source, qemu-bridge-helper, creates the tap and 
attaches it to a linux bridge. the interesting part is that if the 
helper program has the setuid bit and is owned by root, then it is 
executed as root and has the ability to configure the networking. qemu 
itself does not need to be run as root. the following links have more 
information.

http://wiki.qemu.org/Features/HelperNetworking

http://git.qemu.org/?p=qemu.git;a=commit;h=bdef79a2994d6f0383e07e9597675711662b3031

i don't know if the included utility will work with openvswitch. it 
might if you have the brcompat module loaded.

i hope that helps.

mike