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RE: [Xen-devel] A different probklem with save/restore on C/S 14823.

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, "Tim Deegan" <Tim.Deegan@xxxxxxxxxxxxx>
Subject: RE: [Xen-devel] A different probklem with save/restore on C/S 14823.
From: "Petersson, Mats" <Mats.Petersson@xxxxxxx>
Date: Tue, 17 Apr 2007 18:22:24 +0200
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Thread-topic: [Xen-devel] A different probklem with save/restore on C/S 14823.

> -----Original Message-----
> From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx] 
> Sent: 17 April 2007 17:17
> To: Petersson, Mats; Tim Deegan
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] A different probklem with 
> save/restore on C/S 14823.
> On 17/4/07 16:49, "Petersson, Mats" <Mats.Petersson@xxxxxxx> wrote:
> > Got another one that looks like this:
> > (XEN) About to write to NULL
> > (XEN) Done
> > (XEN) Pagetable walk from 0000000000000000:
> > (XEN)  L4[0x000] = 00000000472ea063 000000000000f6ea
> > (XEN)  L3[0x000] = 00000000472e9063 000000000000f6e9
> > (XEN)  L2[0x000] = 00000000472e8067 000000000000f6e8
> > (XEN)  L1[0x000] = 00000000485ae067 0000000000000000
> Okay, I think this is expected behaviour from what I can 
> understand of the
> monitor_table logic. I'll sort it out with Tim.

And when it comes to CR3 and monitor_table, I didn't have the right
thing in the output - I printed the ADDRESS of monitor_table, not the
actual PFN of the monitor table - changing that, and I can see that CR3
and monitor_table is the same thing (aside from one being a FN and the
other a real address). Sorry for that confusion. 

So just to confirm, you think that this should be fixed (i.e. the
null-access should not be possible), but I should test the latest to see
if save/restore works better there, as there is no need to search
further for the actual cause of the "write to zero is possible" problem?

>  Thanks,
>  Keir

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