linux-mips
[Top] [All Lists]

MIPS Function Tracer question

To: ralf@linux-mips.org, linux-mips@linux-mips.org, linux-kernel@vger.kernel.org
Subject: MIPS Function Tracer question
From: Alan Cooper <alcooperx@gmail.com>
Date: Thu, 29 Nov 2012 16:04:40 -0500
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:date:message-id:subject:from:to:content-type; bh=cb9rkGeGOByJYpkiyq8zf0yeahjiKqgkgOzVRy7ot2A=; b=PuWSLwLwtw30zjpEt52P8NmbbBXHt8BnV9mliZx38m/yx4ZK2WPGCtrApbb2TIzQUp rD5g5mkgIZicak5SRS5IDyemN7Plu+nE++ES1Bzyrp4xHljSwvwhSJsxTgDGwTeV3Qch 1JRL4tymYRGvZxF07dqPdCiWpqd4r1/6Fhe5IgAiAUiBRgMvLh8p3/p+pjNIFsoSJ7L8 vqjo3BqA52bL8NbJdAHD9l+wznedx+VV01891rfVPg/OWnNcL+iLEffOGoTa42z1hA/4 9QiX2hAwsnAegnDSIqmaXtctQk0NNH1KO0faYB/6i+9fmgv3uEdCPJReGpc06f8i8MtM gt5g==
List-archive: <http://www.linux-mips.org/archives/linux-mips/>
List-help: <mailto:ecartis@linux-mips.org?Subject=help>
List-id: linux-mips <linux-mips.eddie.linux-mips.org>
List-owner: <mailto:ralf@linux-mips.org>
List-post: <mailto:linux-mips@linux-mips.org>
List-software: Ecartis version 1.0.0
List-subscribe: <mailto:ecartis@linux-mips.org?subject=subscribe%20linux-mips>
List-unsubscribe: <mailto:ecartis@linux-mips.org?subject=unsubscribe%20linux-mips>
Sender: linux-mips-bounce@linux-mips.org
I've been doing some testing of the MIPS Function Tracer functionality
on the 3.3 kernel. I was surprised to find that the option to generate
frame pointers was required for tracing. When I don't enable
FRAME_POINTER along with FUNCTION_TRACER, the kernel hangs on boot. I
also noticed that a checkin to the 3.4 kernel
(b732d439cb43336cd6d7e804ecb2c81193ef63b0) no longer forces on
FRAME_POINTER when FUNCTION_TRACER is selected. I was wondering how it
works in 3.4 and beyond, so I built a Malta kernel from the latest
MIPS tree with FUNCTION_TRACING enabled and tested it with QEMU. The
kernel hung the same way. I can think of 2 reasons for this:
1. Function tracing is broken for MIPS in 3.4 and beyond.
2. The 4.5.3 GNU C compiler I'm using is generating different code for
function tracing.
I was wondering if anyone has MIPS function tracing working in 3.4 or later?

I did figure out why it's hanging and I have some changes that will
allow the function tracer to run without frame pointers, but before I
proceed I want to rule out compiler differences.

Thanks

<Prev in Thread] Current Thread [Next in Thread>