Re: Is: PVH - how to solve maxmem != memory scenario? Was:Re: [PATCH] libxl: create PVH guests with max memory assigned

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Tue, Aug 05, 2014 at 04:51:02PM +0100, Jan Beulich wrote:
> >>> On 05.08.14 at 17:40, <konrad.wilk@oracle.com> wrote:
> > There is a tiny problem with PoD: PCI passthrough.
> > 
> > Right now we don't allow PoD + PCI until the hardware allows it
> >  (if it ever will).
> 
> But PVH doesn't support pass-through so far, does it?

Dom0 is an case of where it does work. My understanding is
that for domU cases it just needs the proper E820 hookup
and it _should_ work.
> 
> > Thought for PV we do allow ballooning and PCI passthrough as we can
> > at least control that the pages that are being ballooned are not going
> > to be used for DMA operations (unless the guest does something stupid
> > and returns an page back to the allocated but still does DMA ops on 
> > the PFN).
> 
> And it would seem possible to permit the combination for PVH if
> there was a documented requirement for the ballooning down to
> happen before any device I/O starts.

The same requirement should be applied to a normal PV guest as well.

> 
> Jan
>