From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754508AbZBOAVJ (ORCPT ); Sat, 14 Feb 2009 19:21:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752772AbZBOAUy (ORCPT ); Sat, 14 Feb 2009 19:20:54 -0500 Received: from gate.crashing.org ([63.228.1.57]:33654 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752717AbZBOAUy (ORCPT ); Sat, 14 Feb 2009 19:20:54 -0500 Subject: Re: [PATCH 1/3] Makefile: Include arch Makefiles as late as possible From: Benjamin Herrenschmidt To: Ingo Molnar Cc: Sam Ravnborg , Anton Vorontsov , Steven Rostedt , Paul Mackerras , linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org In-Reply-To: <20090214220326.GA5200@elte.hu> References: <20090204150755.GA24163@oksana.dev.rtsoft.ru> <20090204150835.GA30027@oksana.dev.rtsoft.ru> <20090204212612.GN22608@elte.hu> <20090214195702.GB1241@uranus.ravnborg.org> <20090214220326.GA5200@elte.hu> Content-Type: text/plain Date: Sun, 15 Feb 2009 11:19:56 +1100 Message-Id: <1234657196.26036.86.camel@pasglop> Mime-Version: 1.0 X-Mailer: Evolution 2.24.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2009-02-14 at 23:03 +0100, Ingo Molnar wrote: > > So the question is: even with FRAME_POINTERS disabled on PPC, is > __builtin_return_address(1)/(2) reliable, and is save_stack_trace() fast? (i.e. > can it walk down the stack frame efficiently, or does it have to scan the full > kernel stack) I.e. does PPC have all the material advantages of frame pointers? Yes, we do. We effectively have frame pointers in fact, they may only be omitted in leaf functions but then gcc __builtin_return_address() knows how to handle that afaik. Cheers, Ben.