From mboxrd@z Thu Jan 1 00:00:00 1970 From: rabin@rab.in (Rabin Vincent) Date: Tue, 9 Nov 2010 19:16:45 +0530 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> <20101108091858.GP16938@pengutronix.de> Message-ID: <20101109134644.GA3163@debian> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Nov 08, 2010 at 10:42:57AM +0000, Catalin Marinas wrote: > 2010/11/8 Uwe Kleine-K?nig : > > On Sat, Nov 06, 2010 at 07:06:28PM +0000, Catalin Marinas wrote: > >> On Saturday, November 6, 2010, Rabin Vincent wrote: > >> > --- 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. > > If a precondition for FRAME_POINTER isn't true, we should not force it > via 'select'. We try to get rid of such warnings in the kernel. > > However, on ARM the FRAME_POINTER depends on !THUMB2_KERNEL but for > Thumb-2 kernels HAVE_FUNCTION_GRAPH_TRACER is also disabled, so there > isn't a dependency issue here. It's more like a personal preference to > keep the changes within the arch/arm tree. OK, new patch below.