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Re: [Xen-devel] question about patch 13252

To: "Lu, Guanqun" <guanqun.lu@xxxxxxxxx>, "jbeulich@xxxxxxxxxx" <jbeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] question about patch 13252
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Thu, 19 Mar 2009 14:49:55 +0000
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On 19/03/2009 14:34, "Lu, Guanqun" <guanqun.lu@xxxxxxxxx> wrote:

> Thanks for your reply.
> It makes a little sense...
> But the problem is that when we do S3,
> we execute load_TR() again (in file arch/x86/acpi/suspend.c),
> and this causes the bug.
> Do we need to go back to non-compat gdt_table when it resumes, and
> switch to compat_gdt_table again?

Ah, I see. There are a few options, the easiest of which is to leave the B
bit clear in both descriptors. I'm not certain whether that actually matters
for any reason, but I think for our purposes it does not.

If Jan can counter my claim, then you can instead switch back to the
non-compat GDT for the LTR, or you can decide which descriptor to set B in
based on which GDT you're running on, or force the B bit in both descriptors
after the LTR, or... You have a few options. :-)

 -- Keir

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