Re: [Hackathon minutes] PV network improvements

[Tim Deegan <tim@xen.org>]

At 11:51 +0100 on 21 May (1369137063), Stefano Stabellini wrote:
> On Tue, 21 May 2013, Tim Deegan wrote:
> > At 19:31 +0100 on 20 May (1369078279), Wei Liu wrote:
> > > On Mon, May 20, 2013 at 03:08:05PM +0100, Stefano Stabellini wrote:
> > > > However it might still be worth considering as an option? The backend is
> > > > still trusted and protected from the frontend, but the frontend wouldn't
> > > > be protected from the backend.
> > > > 
> > > 
> > > I think Dom0 mapping all machine memory is a good starting point.
> > 
> > I _strongly_ disagree.  The opportunity for disaggregation and reduction
> > of privilege in backends is probably Xen's biggest techical advantage
> > and we should not be taking any backward steps there.
> 
> While I agree with you, as a matter of fact the vast majority of Xen
> installations today do not use driver domains.

Sure, and that's a bad thing, right?

> However if the driver domains are "trusted"
> then I think they can also be trusted with a full memory map. After all
> it has been the case for all XenServer, OVM and SLES releases so far
> AFAIK.

...and that's a bad thing, right? :)

> Obviously in an ideal world we would be able to offer both at the same
> time, and maybe George's proposal is exactly what is going to achieve
> that. But I was describing the case that requires us to make a choice.

Righto.  I don't think we need to worry about that yet.  You're all
smart engineers, and I've heard a bunch of good ideas flying around that
address the costs of mapping and unmapping in backends.

Cheers,

Tim.