Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754284Ab0KHJTE (ORCPT ); Mon, 8 Nov 2010 04:19:04 -0500 Received: from metis.ext.pengutronix.de ([92.198.50.35]:47185 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754179Ab0KHJTD (ORCPT ); Mon, 8 Nov 2010 04:19:03 -0500 Date: Mon, 8 Nov 2010 10:18:58 +0100 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Catalin Marinas Cc: Rabin Vincent , Frederic Weisbecker , "linux-kernel@vger.kernel.org" , Steven Rostedt , "linux-arm-kernel@lists.infradead.org" , Tim Bird Subject: Re: [PATCH 6/6] ARM: ftrace: enable function graph tracer Message-ID: <20101108091858.GP16938@pengutronix.de> References: <1289067954-5080-1-git-send-email-rabin@rab.in> <1289067954-5080-6-git-send-email-rabin@rab.in> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-SA-Exim-Connect-IP: 2001:6f8:1178:2:215:17ff:fe12:23b0 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1623 Lines: 36 On Sat, Nov 06, 2010 at 07:06:28PM +0000, Catalin Marinas wrote: > On Saturday, November 6, 2010, Rabin Vincent wrote: > > Add the options to enable the function graph tracer on ARM. ?Function > > graph tracer support requires frame pointers, so exclude Thumb-2 and > > also explicitly select FRAME_POINTER in FUNCTION_GRAPH_TRACER since > > FUNCTION_TRACER doesn't select FRAME_POINTER when ARM_UNWIND is used > > Therefore, with GCC 4.4.0+, you get plain function tracing without frame > > pointers, but you'll need them if you want function graph tracing. > ..... > > --- a/kernel/trace/Kconfig > > +++ b/kernel/trace/Kconfig > > @@ -141,6 +141,7 @@ config FUNCTION_TRACER > > > > ?config FUNCTION_GRAPH_TRACER > > ? ? ? ?bool "Kernel Function Graph Tracer" > > + ? ? ? select FRAME_POINTER if ARM_UNWIND > > Would it be better to modify FRAME_POINTER definition in the ARM > Kconfig so that it is enabled automatically when FUNCTION_GRAPH_TRACER > is enabled? I don't like that suggestion much because it hides the dependency. Moreover a "default y if FUNCTION_GRAPH_TRACER" doesn't work if a precondition for FRAME_POINTER isn't true. Rabin's approach at least generates a warning. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-K?nig | Industrial Linux Solutions | http://www.pengutronix.de/ | -- 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/