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Re: [Xen-devel] write page table in user mode

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] write page table in user mode
From: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Date: Mon, 4 Feb 2008 11:37:39 +0000
Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "Su, Disheng" <disheng.su@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
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At 11:06 +0000 on 04 Feb (1202123216), Keir Fraser wrote:
> Well, this isn't just a matter of degree of aggressiveness. We currently
> don't allow updates from user space at all, ever. The motivation for
> changing that is not to do with aggressiveness of unshadowing, but with
> increased compatibility.

If the problem is really one of unshadowing and reshadowing, then I'm
not sure how to fix this without significantly blunting the teeth of
this heuristic -- even replacing this with an attempted "fast" unshadow
could fail to solve the problem for VMware.

> OTOH it's arguable whether we care about running
> VMware Workstation inside an HVM guest. :-)

We could always fix the VPC performance instead and run VMware inside
VPC inside Xen.


Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Citrix Systems (R&D) Ltd.
[Company #02300071, SL9 0DZ, UK.]

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