Re: Xen/arm: Virtual ITS command queue handling

[Ian Campbell <ian.campbell@citrix.com>]

On Tue, 2015-05-19 at 14:36 +0100, Ian Campbell wrote:
> On Tue, 2015-05-19 at 14:27 +0100, Julien Grall wrote:
> > With the multiple vITS we would have to retrieve the number of vITS.
> > Maybe by extending the xen_arch_domainconfig?
> 
> I'm sure we can find a way.
> 
> The important question is whether we want to go for a N:N vits:pits
> mapping or 1:N.
> 
> So far I think we are leaning (slightly?) towards the 1:N model, if we
> can come up with a satisfactory answer for what to do with global
> commands.

Actually, Julien just mentioned NUMA which I think is a strong argument
for the N:N model.

We need to make a choice here one way or another, since it has knock on
effects on other parts, e.g the handling of SYNC and INVALL etc.

Given that N:N seems likely to be simpler from the Xen side and in any
case doesn't preclude us moving to a 1:N model (or even a 2:N model etc)
in the future how about we start with that?

If there is agreement in taking this direction then I will adjust the
relevant sections of the document to reflect this.

Ian.