Re: [Xen-devel] Re: [PATCH] XEN_DOMAIN_MEMORY options.

From: Konrad Rzeszutek Wilk
Date: Wed Oct 19 2011 - 10:06:43 EST


On Sat, Oct 15, 2011 at 05:42:48PM +0100, Ian Campbell wrote:
> On Sat, 2011-10-15 at 09:05 -0400, Konrad Rzeszutek Wilk wrote:
> > > On 10/14/2011 04:41 PM, Jeremy Fitzhardinge wrote:
>
> > > >While it would be very silly to put 128GB of actual RAM on a 32-bit
> > > >machine, systems can have non-contiguous RAM placed at high addresses,
> > > >which would no longer be accessible.
> >
> > Do you have some ideas of which machines that might be?
>
> Even if you were on such a machine, the discontiguity
> (discontiguousness?) wouldn't ever be reflected in the pseudo-physical
> memory map, would it? So since this variable controls the maximum size
> of the p2m (rather than the m2p) it doesn't need to be larger than the
> maximum sane 32 bit guest size (<64G).

I think it is the other way around. The M2P would not be affected but
the P2M might? The "discontinuity" is in the E820 right? (so mega big
holes in it).
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