Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758417AbYG1O5s (ORCPT ); Mon, 28 Jul 2008 10:57:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757733AbYG1Ozx (ORCPT ); Mon, 28 Jul 2008 10:55:53 -0400 Received: from extu-mxob-1.symantec.com ([216.10.194.28]:45258 "EHLO extu-mxob-1.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757713AbYG1Ozw (ORCPT ); Mon, 28 Jul 2008 10:55:52 -0400 Date: Mon, 28 Jul 2008 15:54:30 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@blonde.site To: Ingo Molnar cc: Mike Travis , Ben Herrenschmidt , linux-kernel@vger.kernel.org, the arch/x86 maintainers , Linuxppc-dev@ozlabs.org, Arjan van de Ven , Linus Torvalds Subject: Re: CONFIG_FRAME_POINTER [was [PATCH] x86: BUILD_IRQ say .text] In-Reply-To: <20080728144133.GH18144@elte.hu> Message-ID: References: <20080724104459.GI28817@elte.hu> <20080728144133.GH18144@elte.hu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1268 Lines: 25 On Mon, 28 Jul 2008, Ingo Molnar wrote: > * Hugh Dickins wrote: > > > I rather think CONFIG_FRAME_POINTER shouldn't exist at all (or be a > > private, config-user-invisible, specific-to-a-few-arches thing): what > > one wants to configure is how far to sacrifice cpu performance and > > kernel smallness to getting a good stacktrace. Frame pointer is just > > an implementation detail on that, appropriate to some arches. Perhaps > > three settings: no stacktrace, fair stacktrace, best stacktrace. > > actually, we consciously use and rely on frame pointers on x86. The > runtime cost on 64-bit is miniscule and the improved backtrace output in > recent kernels makes backtraces _much_ easier to interpret: Just to clarify, no way was I criticizing the use of frame pointers on x86. What I don't care for is that CONFIG_FRAME_POINTER is used by common code (e.g. top level Makefile, and various debug Kconfigs), when I see it as an arch-specific technique for getting best stacktrace. Hugh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/