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

[Arnd Bergmann <arnd@arndb.de>]

On Wednesday 27 January 2010, Anthony Liguori wrote:
> >> I think -net socket,fd should just be (trivially) extended to work with raw
> >> sockets out of the box, with no support for opening it. Then you can have
> >> libvirt or some wrapper open a raw socket and a private namespace and just pass it
> >> down.
> >>      
> > That'd work. Anthony?
> 
> The fundamental problem that I have with all of this is that we should 
> not be introducing new network backends that are based around something 
> only a developer is going to understand.  If I'm a user and I want to 
> use an external switch in VEPA mode, how in the world am I going to know 
> that I'm supposed to use the -net raw backend or the -net socket 
> backend?  It might as well be the -net butterflies backend as far as a 
> user is concerned.

My point is that we already have -net socket,fd and any user that passes
an fd into that already knows what he wants to do with it. Making it
work with raw sockets is just a natural extension to this, which works
on all kernels and (with separate namespaces) is reasonably secure.

I fully agree that we should not introduce further network backends
that would confuse users, but making the existing backends more
flexible is something entirely different.

	Arnd