linux-kernel - Re: CONFIG_CC_STACKPROTECTOR

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Date:   Tue, 9 Jul 2019 23:02:30 +0530
From:   Muni Sekhar <munisekharrms@...il.com>
To:     Denis Kirjanov <kirjanov@...il.com>
Cc:     kernelnewbies <kernelnewbies@...nelnewbies.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: CONFIG_CC_STACKPROTECTOR_STRONG

On Tue, Jul 9, 2019 at 10:56 PM Denis Kirjanov <kirjanov@...il.com> wrote:
>
>
>
> On Tuesday, July 9, 2019, Muni Sekhar <munisekharrms@...il.com> wrote:
>>
>> Hi All,
>>
>>
>> My Kernel is built with the following options:
>>
>>
>>
>> CONFIG_CC_STACKPROTECTOR=y
>>
>> CONFIG_CC_STACKPROTECTOR_STRONG=y
>>
>>
>>
>>
>>
>> We use out-of-tree kernel modules in our project and I need to measure the performance of it by using a bit older gcc version 4.8.5.
>>
>>
>>
>> I can build the modules with gcc above 5 version, but when I try to use gcc version 4.8.5 I’m getting the following error:
>>
>>
>>
>> Makefile:693: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>>
>>
>>
>> So it looks like gcc 4.8.5 does not support CONFIG_CC_STACKPROTECTOR_STRONG option, but how to instruct gcc to ignore this one?
>>
>>
>>
>> In runtime, is it possible to instruct kernel to ignore “CONFIG_CC_STACKPROTECTOR_STRONG=y” (without building the kernel) by using sysctl or any other method?
>>
>>
>
>
> Just disable it in your .config file

I disabled in /lib/modules/$(uname -r)/build/.config, but still get
that error. Does kernel needs to be recompiled?

CONFIG_CC_STACKPROTECTOR=y
# CONFIG_CC_STACKPROTECTOR_NONE is not set
# CONFIG_CC_STACKPROTECTOR_REGULAR is not set
# CONFIG_CC_STACKPROTECTOR_STRONG is not set

>
>
>>
>> Any help is appreciated.
>>
>>
>>
>> --
>> Thanks,
>> Sekhar
>
>
>
> --
> Regards / Mit besten Grüßen,
> Denis
>


-- 
Thanks,
Sekhar