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Re: [Xen-devel] RE: kernel panic when enable x2apic

To: Keir Fraser <keir@xxxxxxx>
Subject: Re: [Xen-devel] RE: kernel panic when enable x2apic
From: Weidong Han <weidong.han@xxxxxxxxx>
Date: Wed, 01 Dec 2010 08:42:50 +0800
Cc: "Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>, Sander Eikelenboom <linux@xxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx>
Delivery-date: Tue, 30 Nov 2010 16:43:48 -0800
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Keir Fraser wrote:
On 30/11/2010 09:23, "Keir Fraser" <keir@xxxxxxx> wrote:

The obvious solution is to remove
boot_cpu_data.x86_capability[4] = cpuid_ecx(1) in start_vmx. It indeed
works with the change. I will send out the patch after more tests.
Yes, the write to x86_capability is totally unnecessary. There is a similar
pointless one in SVM code -- in fact they don't even manage to write to the
correct array element of x86_capability[]!

Removing both writes to x86_capability[] would be an appropriate fix for 4.0
branch as well.

I applied a fix to xen-unstable and xen-4.0-testing. Eyeballing plus a quick
test convinces me it is absolutely fine. I credited you in the changeset
comment, I hope that's okay.



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