linux-kernel - Re: How can I turn off/disable -O2/-Os optimization?

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Message-ID: <20120506132827.GB3824@nuttenaction>
Date:	Sun, 6 May 2012 15:28:27 +0200
From:	Hagen Paul Pfeifer <hagen@...u.net>
To:	Renato Westphal <renatowestphal@...il.com>
Cc:	Zhihua Che <zhihua.che@...il.com>,
	Randy Dunlap <rdunlap@...otime.net>,
	linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Subject: Re: How can I turn off/disable -O2/-Os optimization?

* Renato Westphal | 2012-05-05 23:00:48 [-0300]:

>>> You could try the new CONFIG_READABLE_ASM patch:
>>>  http://marc.info/?l=linux-kernel&m=133296079716268&w=2

Maybe remove "-Os" on a global basis is not wanted nor required. Maybe a per
directory, per file or per function basis may superior!

make DISABLE_OPTIMIZATION=net/sched/sch_api.c

But still all core constructs defined in top level header files must be
compatible for directory/file basis to be build with no optimization at all.

One way to un-optmize fine-granular is GCC's optmize pragma [1].

Hagen

PS: such a functionality may be convenient for perf probe too! (to hook into
probepoints which are currently optimized out)

[1] http://gcc.gnu.org/onlinedocs/gcc/Function-Specific-Option-Pragmas.html
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