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

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Date:	Mon, 2 Apr 2012 16:44:15 +0800
From:	Zhihua Che <zhihua.che@...il.com>
To:	Randy Dunlap <rdunlap@...otime.net>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: How can I turn off/disable -O2/-Os optimization?

在 2012年4月2日 上午12:49，Randy Dunlap <rdunlap@...otime.net> 写道：
> On 04/01/2012 09:31 AM, Zhihua Che wrote:
>
>> Hi, everyone
>>
>>     I'm debugging linux kernel using kgdb/qemu， but I find that the
>> execution order didn't math the program order usually.  I guess it was
>> because the compiling optimization. So I decided to remove -O options
>> in Makefiles.
>>     First I removed -Ox in variables HOSTCFLAGS/HOSTCXXFLAGS in
>> <src_root_dir>/Makefile around line 248 and -Ox in variable
>> KBUILD_CFLAGS in <src_root_dir>/arch/x86/boot/Makefile around line 55.
>> But it didn't work, the step execution still didn't follow the program
>> order. Then I found I missed -Ox in KBUILD_CFLAGS in
>> <src_root_dir>/Makefile around line 562, so I removed them, but this
>> time, the compiling failed, complaining
>>     rcupdate.h:917:2: error: size of unnamed array is negative
>>    And finally, after grep, I find there are a load of -O2 option are
>> assigned in a load of Makefiles. So, How could I disable -O
>> optimization for debugging?
>>
>>    Thanks for any tips
>> --
>
>
> You could try the new CONFIG_READABLE_ASM patch:
>  http://marc.info/?l=linux-kernel&m=133296079716268&w=2
>
>
> --
> ~Randy

Hi,
    I tried your patch, and it seemed not to work:-(. It still didn't
follow the program order
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