linux-kernel - Re: perf hw in kexeced kernel broken in tip

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Date:	Wed, 08 Dec 2010 15:20:37 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Don Zickus <dzickus@...hat.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Vivek Goyal <vgoyal@...hat.com>,
	Yinghai Lu <yinghai@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	Jason Wessel <jason.wessel@...driver.com>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	Haren Myneni <hbabu@...ibm.com>
Subject: Re: perf hw  in kexeced kernel broken in tip

Don Zickus <dzickus@...hat.com> writes:

> On Wed, Dec 08, 2010 at 03:59:16PM +0100, Peter Zijlstra wrote:
>> On Wed, 2010-12-08 at 15:20 +0100, Peter Zijlstra wrote:
>> 
>> > > I wonder if you should reverse these checks.  If the bios has the perf
>> > > counter enabled, there might be a high chance that it fails the first
>> > > check and never gets to the actually bios checks.
>> > 
>> > Ah, good point. 
>> 
>> Something like so..
>
> This seems to work correctly on my Nehalem and broken bios machines during
> boot and kexec.  As expected it fails during kdump.  My p4 box failed
> during kexec for some reason.  But p4 has other issues.

Does the kdump kernel still boot?

It looks like it should I just want to double check.

Eric
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