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Re: [Xen-devel] Pinning L1 page table with wrpt

To: Jacob Gorm Hansen <jacobg@xxxxxxx>
Subject: Re: [Xen-devel] Pinning L1 page table with wrpt
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 15 Aug 2005 10:16:21 +0100
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On 15 Aug 2005, at 09:55, Jacob Gorm Hansen wrote:

And then Xen will pin them for me recursively, or they will not be
pinned at all but just checked against having writable references? I
seem to have a problem when combining writable pagetables and the
traditional pinned ones in the same domain. The pagetables I inherit
from the domain builder need to be unpinned before I can use the pages
they reference for my own page tables, or I get complaints about trying
to create a writable linear p.t.

Xen will infer their type when you pin the L2. At that point, they behave exactly the same as a pinned L1, until they are detached from the pinned L2 or the L2 itself is unpinned.

We play games with the initial p.t. in linux 2.6 as well. The code in arch/xen/i386/mm/init.c might be worth looking at, although it's pretty twisted stuff!

 -- Keir

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