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Re: [Xen-devel] [PATCH] This patch fixes several issues related to vmxas

To: "Li, Xin B" <xin.b.li@xxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] This patch fixes several issues related to vmxassist
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Thu, 30 Mar 2006 17:38:23 +0100
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On 30 Mar 2006, at 17:09, Li, Xin B wrote:

Changeset 9366 from Leendert is to support big real mode, in turn to
support the SYSLINUX/ISOLINUX.
so the address calculation is kludgy, the point here is to identify if a
cpu is in big real mode, if so, we should use protected mode addressing
even in real mode.

Shouldn't we get the Xen portion of vmxassist help us with that, for example by making the hidden descriptor info (base, limit, etc) available to us? There's already a method for loading that stuff out of Xen, right?

Looks to me as though the kludge won't work if you unluckily load a real-mode segment value that happens to also reference a 'big segment' in the currently registered GDT.

 -- Keir


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