linux-kernel - Re: [PATCH 0/2] perf: Use LBR for machine/oops debugging

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Message-ID: <1269872059.12097.338.camel@laptop>
Date:	Mon, 29 Mar 2010 16:14:19 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	mingo@...e.hu, Linus Torvalds <torvalds@...l.org>,
	linux-kernel@...r.kernel.org, Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 0/2] perf: Use LBR for machine/oops debugging

On Mon, 2010-03-29 at 15:08 +0200, Andi Kleen wrote:
> Peter Zijlstra <a.p.zijlstra@...llo.nl> writes:
> 
> > The LBRs are relatively cheap to keep enabled and provide some history
> > to OOPSen, also some CPUs are reported to keep them over soft-reset,
> > which allows us to use them to debug things like tripple faults.
> >
> > Therefore introduce a boot option: lbr_debug=on, which always enable
> > the LBRs and will print the LBRs on CPU init and die().
> 
> 
> die is too late. they will only contain the oops code then.

We do an lbr_off() in oops_begin(), or is there a better/earlier place
we can do that?

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