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Subject: Re: [PATCH v7 04/17] tracing: add static function tracer support
 for MIPS
From: Wu Zhangjin <wuzhangjin@gmail.com>
Reply-To: wuzhangjin@gmail.com
To: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org, linux-kernel@vger.kernel.org,
       zhangfx@lemote.com, zhouqg@gmail.com,
       Ralf Baechle <ralf@linux-mips.org>, rostedt@goodmis.org,
       Frederic Weisbecker <fweisbec@gmail.com>, Ingo Molnar <mingo@elte.hu>,
       Nicholas Mc Guire <der.herr@hofr.at>,
       Richard Sandiford <rdsandiford@googlemail.com>,
       Patrik Kluba <kpajko79@gmail.com>, Thomas Gleixner <tglx@linutronix.de>,
       Michal Simek <monstr@monstr.eu>
In-Reply-To: <4AF8B31C.5030802@caviumnetworks.com>
References: <9dc81a7a9e5a292cccdf465c533a2b08d19d6021.1257779502.git.wuzhangjin@gmail.com>
	 <b99c08397d9ff92ac5a72bda9131df41b702fc71.1257779502.git.wuzhangjin@gmail.com>
	 <8f579e2cece16cd22358a4ec143ef6a8c462639b.1257779502.git.wuzhangjin@gmail.com>
	 <cefe074f5eb3cfbc2e0bb41b0c1f61fcd0190d90.1257779502.git.wuzhangjin@gmail.com>
	 <4AF8B31C.5030802@caviumnetworks.com>
Content-Type: text/plain; charset="UTF-8"
Organization: DSLab, Lanzhou University, China
Date: Tue, 10 Nov 2009 09:00:17 +0800
Message-ID: <1257814817.2822.3.camel@falcon.domain.org>
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Hi,

On Mon, 2009-11-09 at 16:26 -0800, David Daney wrote: 
> Wu Zhangjin wrote:
> 
> >  
> > +ifndef CONFIG_FUNCTION_TRACER
> >  cflags-y := -ffunction-sections
> > +else
> > +cflags-y := -mlong-calls
> > +endif
> >  cflags-y += $(call cc-option, -mno-check-zero-division)
> >  
> 
> That doesn't make sense to me.  Modules are already compiled with 
> -mlong-calls.  The only time you would need the entire kernel compiled 
> with -mlong-calls is if the tracer were in a module.  The logic here 
> doesn't seem to reflect that.

Yes, I knew the module have gotten the -mlong-calls, Here we just want
to use -mlong-calls for the whole kernel, and then we get the same
_mcount stuff in the whole kernel, at last, we can use the same
scripts/recordmcount.pl and ftrace_make_nop & ftrace_make_call for the
dynamic ftracer.

And seems we only need to enable it for the dynamic one. So, I will
split it out into it's own patch later.

Thanks & Regards,
	Wu Zhangjin

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