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Re: [Xen-devel] 2MB page PV guest support clarification

To: Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>, Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "Mick.Jordan@xxxxxxx" <Mick.Jordan@xxxxxxx>
Subject: Re: [Xen-devel] 2MB page PV guest support clarification
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Sat, 28 Feb 2009 11:12:06 +0000
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On 28/02/2009 00:03, "Ian Pratt" <Ian.Pratt@xxxxxxxxxxxxx> wrote:

>> Its a work in progress, but there's nothing usable yet, as far as I
>> know.
> 
> Oracle have been working on PV 2MB page support, and I expect they'll pitch in
> with an update.
> 
> Over the last 18 months or so there have been a number of changes to xen's PV
> PT handling that make support of 2MB pages significantly easier than it was
> previously. However, the guest has to be careful how it uses them as it can't
> alias any memory that may be used for storing pagetables pages (that must be
> RO).

Oracle already got their code checked in. You have to specify
'allowhugepage' on Xen's command line to enable it. It has limitations, such
as save/restore doesn't work.

 -- Keir



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