Re: [PATCH qemu-kvm] Add raw(af_packet) network backend to qemu

Michael S. Tsirkin
2010-01-27T17:02:24Z

On Wed, Jan 27, 2010 at 08:07:11AM -0600, Anthony Liguori wrote:
> On 01/27/2010 03:24 AM, Michael S. Tsirkin wrote:
>> I am not sure I agree with this sentiment. The main issue being that
>> macvtap doesn't exist on all kernels :).
>
> Neither does vhost ;-) If it were just that as the difference, I'd be
> inclined to agree, but macvtap is much better from a security PoV.
>
>>> Not to mention that from a user perspective, raw makes almost no sense
>>> as it's an obscure socket protocol family.
>>>
>>> A user wants to do useful things like bridged networking or direct VF
>>> assignment. We should have -net backends that reflect things that make
>>> sense to a user.
>>>
>>> Regards,
>>>
>>> Anthony Liguori
>>>
>>
>> I agree to that. People don't even seem to agree whether it's a raw
>> socket or a packet socket :) We need a better name for this option: what
>> it really does is rely on an external device to loopback a packet to us,
>> so how about -net loopback or -net extbridge?
>>
>
> Specifically for VEPA, something like:
>
> -net extbridge,if=eth0
>
> or even
>
> -net vepa,if=eth0
>
> Would be fantastic.

extbridge is IMO better.

> I think the best way to achieve this is to
> introduce a small helper that gets called and can create a macvtap
> device and hand the file descriptor back to qemu :-) A builtin backend
> would also be fine since we don't have the helper infrastructure.

Excellent.
Sridhar, this is actually not a lot of work on top of what you
already posted.

> Regards,
>
> Anthony Liguori