WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

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

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] WP flag in CR0, setting
From: Simon Kagstrom <simon.kagstrom@xxxxxx>
Date: Thu, 15 Jun 2006 10:00:20 +0200
Cc: xen-devel list <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Thu, 15 Jun 2006 00:59:52 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <ecb1312515704916b90d2c4d1f89a695@xxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <87y7vzoq6e.wl%simon.kagstrom@xxxxxx> <ecb1312515704916b90d2c4d1f89a695@xxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Wanderlust/2.15.2 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.8 (Shijō) APEL/10.6 Emacs/21.4 (i486-pc-linux-gnu) MULE/5.0 (SAKAKI)
At Wed, 14 Jun 2006 14:00:16 +0100,
Keir Fraser wrote:
> 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.

Thanks for the explanation. Would the WP flag work in a HVM setting?

// Simon

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel