Re: [PATCH/RFC 7/9] Virtual network guest device driver

Christian Bornträger
2007-05-14T12:24:44Z

On Monday 14 May 2007 14:05, Avi Kivity wrote:
> But I agree that the growing code base is a problem. With the block
> driver we can probably keep the host side in userspace, but to do the
> same for networking is much more work. I do think (now) that it is doable.

Interesting. What kind of userspace networking do you have in mind?

One of the first trys from Carsten was to use tun/tap, which proved to be slow
performance-wise.

What I had in mind was some kind of switch in userspace. That would allow
non-root guests to define there own private networks. We could use Linux fast
pipe implementation for guest-to-guest communication.

The questions is how to connect user space networks to the host ones?
- tun/tap is quite slow
- last time we checked, netfiler offered only IP hooks (if you dont use the
bridging code)
- raw sockets get tricky if you do in/out at the same time because you have to
manually deal with loops

This reminds me, that we actually have another party doing virtual networking
between guests: UML. User mode linux actually can do networking/switching in
userspace, but I cannot tell how well UMLs concept works out.

Christian