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Re: [Xen-devel] WP flag in CR0, setting

To: Simon Kagstrom <simon.kagstrom@xxxxxx>
Subject: Re: [Xen-devel] WP flag in CR0, setting
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Wed, 14 Jun 2006 14:00:16 +0100
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On 14 Jun 2006, at 13:52, Simon Kagstrom wrote:

I have a slight problem in my guest port with the WP bit in CR0. The
original kernel maps certain kernel pages to user-mode read-only and
relies on the kernel being able to modify these despite the read-only
bit being set in the pages. This in turn requires that the WP bit is
unset in CR0.

We can't support this. We rely on write protection for all sorts of things (e.g., prevent guest write access to page tables). You'll have to temporarily make the mapping writable, or make a kernel-private writable mapping.

 -- Keir


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