From mboxrd@z Thu Jan 1 00:00:00 1970 From: u.kleine-koenig@pengutronix.de (Uwe =?iso-8859-1?Q?Kleine-K=F6nig?=) Date: Mon, 8 Nov 2010 10:18:58 +0100 Subject: [PATCH 6/6] ARM: ftrace: enable function graph tracer In-Reply-To: References: <1289067954-5080-1-git-send-email-rabin@rab.in> <1289067954-5080-6-git-send-email-rabin@rab.in> Message-ID: <20101108091858.GP16938@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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/ |