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From: Anton Vorontsov <avorontsov@ru.mvista.com>
To: Steven Rostedt <srostedt@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>, Paul Mackerras <paulus@samba.org>,
	linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org
Subject: Re: [PATCH v2] ftrace: On PowerPC we don't need frame pointers for CALLER_ADDRs
Date: Tue, 3 Feb 2009 21:59:33 +0300	[thread overview]
Message-ID: <20090203185933.GA9878@oksana.dev.rtsoft.ru> (raw)
In-Reply-To: <1233678738.16878.5.camel@localhost.localdomain>

On Tue, Feb 03, 2009 at 11:32:18AM -0500, Steven Rostedt wrote:
> 
> On Tue, 2009-02-03 at 19:19 +0300, Anton Vorontsov wrote:
> > On Tue, Feb 03, 2009 at 05:06:45PM +0100, Ingo Molnar wrote:
> 
> > [1] Btw, why exactly do we need the -fno-omit-frame-pointer for
> > "FUNCTION_TRCER" tracer? Why just -pg isn't sufficient?..
> > 
> 
> The problem is this that is in the toplevel Makefile:
> 
> 
> ifdef CONFIG_FRAME_POINTER
> KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
> else
> KBUILD_CFLAGS	+= -fomit-frame-pointer
> endif
> 
> 
> -pg is incompatible with -fomit-frame-pointer

Ah...

$ gcc -pg -fomit-frame-pointer -S c.c
gcc: -pg and -fomit-frame-pointer are incompatible

It's hard-coded in gcc, in the code that don't know about
architecture details.

But on PowerPC -O1 implies -fomit-frame-pointer, that is

gcc -pg -O1 -fno-omit-frame-pointer
and
gcc -pg -O1

produce different outputs. Thus -pg -O should be the same
as "-pg -O -fomit-framepointer".

-- 
Anton Vorontsov
email: cbouatmailru@gmail.com
irc://irc.freenode.net/bd2

  reply	other threads:[~2009-02-03 18:59 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-31 19:06 [PATCH] ftrace: On PowerPC we don't need frame pointers for CALLER_ADDRs Anton Vorontsov
2009-02-02  0:35 ` Benjamin Herrenschmidt
2009-02-02 14:04   ` Steven Rostedt
2009-02-03 14:56     ` [PATCH v2] " Anton Vorontsov
2009-02-03 16:06       ` Ingo Molnar
2009-02-03 16:19         ` Anton Vorontsov
2009-02-03 16:32           ` Steven Rostedt
2009-02-03 18:59             ` Anton Vorontsov [this message]
2009-02-04  0:34               ` Benjamin Herrenschmidt
2009-02-04 15:07           ` Anton Vorontsov
2009-02-04 15:08             ` [PATCH 1/3] Makefile: Include arch Makefiles as late as possible Anton Vorontsov
2009-02-04 21:26               ` Ingo Molnar
2009-02-11  3:51                 ` Benjamin Herrenschmidt
2009-02-11 13:23                   ` Ingo Molnar
2009-02-11 14:11                     ` Steven Rostedt
2009-02-14 19:58                   ` Sam Ravnborg
2009-02-14 19:57                 ` Sam Ravnborg
2009-02-14 22:03                   ` Ingo Molnar
2009-02-15  0:19                     ` Benjamin Herrenschmidt
2009-02-15  8:09                       ` Ingo Molnar
2009-02-16 14:20                   ` Anton Vorontsov
2009-02-16 14:53                     ` Anton Vorontsov
2009-02-16 20:04                       ` Sam Ravnborg
2009-02-16 16:08                     ` Anton Vorontsov
2009-02-16 17:22                       ` Ingo Molnar
2009-02-04 15:08             ` [PATCH 2/3] powerpc: Make it possible to safely select CONFIG_FRAME_POINTER Anton Vorontsov
2009-02-05  0:31               ` Benjamin Herrenschmidt
2009-02-05  0:35                 ` Steven Rostedt
2009-02-05  1:12                   ` Anton Vorontsov
2009-02-05  1:15                   ` Benjamin Herrenschmidt
2009-02-05  1:30                     ` Anton Vorontsov
2009-02-05 15:45                       ` Anton Vorontsov
2009-02-04 15:08             ` [PATCH 3/3] tracing: Tracers that use CALLER_ADDR macros should select FRAME_POINTER Anton Vorontsov
2009-02-04 15:26               ` Frédéric Weisbecker
2009-02-04 15:31                 ` Steven Rostedt
2009-02-04 15:36                 ` Anton Vorontsov
2009-02-04 16:50                   ` Frédéric Weisbecker
2009-02-04  8:17       ` [PATCH v2] ftrace: On PowerPC we don't need frame pointers forCALLER_ADDRs Usha Rani Konudula
2009-02-04  8:37         ` Usha Rani Konudula

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