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Re: [Xen-devel] [PATCH 1 of 6] REDO: mem_access & mem_access 2: introduc

To: Joe Epstein <jepstein98@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 1 of 6] REDO: mem_access & mem_access 2: introduce P2M mem_access types
From: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Date: Wed, 5 Jan 2011 14:42:17 +0000
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At 22:07 +0000 on 04 Jan (1294178829), Joe Epstein wrote:
> * Introduces access types for each page, giving independent read, write, and
>   execute permissions for each page.  The permissions are restrictive from
>   what the page type gives: for example, a p2m_type_ro page with an access of
>   p2m_access_rw would have read-only permissions in total, as p2m_type_ro
>   removed write access and p2m_access_rw removed execute access.
> * Implements the access flag storage for EPT, moving some bits from P2M type,
>   which had 10 bits of storage, to the four bits for access.
> * Access flags are stored according to a loose consistency contract, where
>   pages can be reset to the default access permissions at any time.  Right
>   now, that happens on page type changes, where one would want to reevaluate
>   whether permissions make sense for that page as they are anyway.
> Signed-off-by: Joe Epstein <jepstein98@xxxxxxxxx>

I won't apply this until the rest of the series is ready, but:
Acked-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>



Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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