From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751434Ab0C2NQ3 (ORCPT ); Mon, 29 Mar 2010 09:16:29 -0400 Received: from smtp-out.google.com ([74.125.121.35]:19207 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750957Ab0C2NQ1 (ORCPT ); Mon, 29 Mar 2010 09:16:27 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:x-system-of-record; b=MQWMzEChuhTZLgiv3hGnXvuKQseLeNUC5jQcvq8WLT5nQRqF4HDe01QiVZ3WPE8L9 WDEuQdVhBMthIQMSQLyMg== MIME-Version: 1.0 In-Reply-To: <87bpe7qnrg.fsf@basil.nowhere.org> References: <20100329122021.765109681@chello.nl> <87bpe7qnrg.fsf@basil.nowhere.org> Date: Mon, 29 Mar 2010 14:16:23 +0100 Message-ID: Subject: Re: [PATCH 0/2] perf: Use LBR for machine/oops debugging From: Stephane Eranian To: Andi Kleen Cc: Peter Zijlstra , mingo@elte.hu, Linus Torvalds , linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 29, 2010 at 2:08 PM, Andi Kleen wrote: > Peter Zijlstra 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. > Most likely yes, especially with small LBR, such as on Intel Core. > -Andi > > -- > ak@linux.intel.com -- Speaking for myself only. >