Re: [Xen-devel] [PATCH 0/2] xen: Switch to virtual mapped linear p2m list

[Juergen Gross]

On 10/28/2014 01:46 PM, Andrew Cooper wrote:
> On 28/10/14 12:44, David Vrabel wrote:
> > On 28/10/14 12:42, Andrew Cooper wrote:
> > > On 28/10/14 12:39, David Vrabel wrote:
> > > > On 28/10/14 12:07, Juergen Gross wrote:
> > > > > Okay, back to the original question: is the (up to) 64 MB virtual
> > > > > mapping of the p2m list on 32-bit pv domains a problem or not?
> > > > I think up-to 64 MiB of vmalloc area is fine.  The vmalloc space can be
> > > > increased with a command line option in the unlikely event that there
> > > > are domUs that would be affected.
> > > >
> > > > > If yes, the virtual mapped linear p2m list could still be used on
> > > > > 64 bit domains, paving the way for support of more than 512 GB of
> > > > > domain memory. OTOH having to keep the p2m tree coding alive isn't
> > > > > my favorite solution...
> > > > Having to keep both the tree and linear p2m code would be awful.  Let's
> > > > not do this!
> > > >
> > > > David
> > > How is the toolstack expected to find and mutate this p2m on migrate?
> > > The toolstack does not use guest pagetables.
> > The p2m code maintains two trees.  One for use by the guest and one for
> > use by the toolstack.  This series replaces the first tree with the
> > linear array (at least that's how I understand it -- I've not reviewed
> > the series in detail yet).
>
> Ah - fine (if that is how it works).

That's the plan, yes.


Juergen

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