lkml.org 
[lkml]   [2010]   [Nov]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patches in this message
/
Date
From
SubjectRe: [PATCH 6/6] ARM: ftrace: enable function graph tracer
On Mon, Nov 08, 2010 at 10:42:57AM +0000, Catalin Marinas wrote:
> 2010/11/8 Uwe Kleine-König <u.kleine-koenig@pengutronix.de>:
> > On Sat, Nov 06, 2010 at 07:06:28PM +0000, Catalin Marinas wrote:
> >> On Saturday, November 6, 2010, Rabin Vincent <rabin@rab.in> 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.

From ce3856933234b0976068be8bdc46340dcf31ef6f Mon Sep 17 00:00:00 2001
From: Rabin Vincent <rabin@rab.in>
Date: Sat, 6 Nov 2010 23:03:53 +0530
Subject: [PATCHv2] ARM: ftrace: enable function graph tracer

Add the options to enable the function graph tracer on ARM. Function
graph tracer support requires frame pointers, so exclude Thumb-2 and
also make sure FRAME_POINTER gets enabled when FUNCTION_GRAPH_TRACER is
used, 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.

Signed-off-by: Rabin Vincent <rabin@rab.in>
---
arch/arm/Kconfig | 1 +
arch/arm/Kconfig.debug | 2 +-
2 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a19a526..c5e96ff 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -14,6 +14,7 @@ config ARM
select HAVE_FUNCTION_TRACER if (!XIP_KERNEL)
select HAVE_FTRACE_MCOUNT_RECORD if (!XIP_KERNEL)
select HAVE_DYNAMIC_FTRACE if (!XIP_KERNEL)
+ select HAVE_FUNCTION_GRAPH_TRACER if (!THUMB2_KERNEL)
select HAVE_GENERIC_DMA_COHERENT
select HAVE_KERNEL_GZIP
select HAVE_KERNEL_LZO
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index 2fd0b99..eac62085 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -23,7 +23,7 @@ config STRICT_DEVMEM
config FRAME_POINTER
bool
depends on !THUMB2_KERNEL
- default y if !ARM_UNWIND
+ default y if !ARM_UNWIND || FUNCTION_GRAPH_TRACER
help
If you say N here, the resulting kernel will be slightly smaller and
faster. However, if neither FRAME_POINTER nor ARM_UNWIND are enabled,
--
1.7.2.3
--
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/

\
 
 \ /
  Last update: 2010-11-09 14:49    [W:0.081 / U:0.472 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site