From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934192Ab0CMRhU (ORCPT ); Sat, 13 Mar 2010 12:37:20 -0500 Received: from cpe-74-67-89-75.stny.res.rr.com ([74.67.89.75]:41247 "EHLO localhost.localdomain" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932937Ab0CMRhT convert rfc822-to-8bit (ORCPT ); Sat, 13 Mar 2010 12:37:19 -0500 Subject: Re: [PATCH 03/10] ftrace: allow building without frame pointers From: Steven Rostedt To: Rabin Vincent Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Frederic Weisbecker , Ingo Molnar , Abhishek Sagar , Uwe =?ISO-8859-1?Q?Kleine-K=F6nig?= In-Reply-To: <1268462987-8271-4-git-send-email-rabin@rab.in> References: <1268462987-8271-1-git-send-email-rabin@rab.in> <1268462987-8271-4-git-send-email-rabin@rab.in> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Sat, 13 Mar 2010 12:36:32 -0500 Message-ID: <1268501792.3366.7.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.28.2 (2.28.2-1.fc12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2010-03-13 at 12:19 +0530, Rabin Vincent wrote: > With current gcc, compiling with both -pg and -fomit-frame-pointer is > not allowed. However, -pg can be used to build without actually > specying -fno-omit-frame-pointer, upon which the defaut behaviour for > the target will be used. > > On ARM, it is not possible to build a Thumb-2 kernel with > -fno-omit-frame-pointer (FRAME_POINTERS depends on !THUMB2_KERNEL). In > order to support ftrace for Thumb-2, we need to be able to allow a > combination of FUNCTION_TRACER and !FRAME_POINTER. We do this by > omitting -fomit-frame-pointer if ftrace is enabled. > > Acked-by: Frederic Weisbecker > Signed-off-by: Rabin Vincent > --- > v2: Better comment. > > Makefile | 7 +++++++ > 1 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/Makefile b/Makefile > index 08ff02d..61404e0 100644 > --- a/Makefile > +++ b/Makefile > @@ -546,8 +546,15 @@ endif > ifdef CONFIG_FRAME_POINTER > KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls > else > +# Some targets (ARM with Thumb2, for example), can't be built with frame > +# pointers. For those, we don't have FUNCTION_TRACER automatically > +# select FRAME_POINTER. However, FUNCTION_TRACER adds -pg, and this is > +# incompatible with -fomit-frame-pointer with current GCC, so we don't use > +# -fomit-frame-pointer with FUNCTION_TRACER. > +ifndef CONFIG_FUNCTION_TRACER > KBUILD_CFLAGS += -fomit-frame-pointer I believe this is correct, but have you tested this on other archs other than ARM? I can do it for x86 and PPC, but it will need to wait as those machines are currently performing stress tests. -- Steve > endif > +endif > > ifdef CONFIG_DEBUG_INFO > KBUILD_CFLAGS += -g