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From:   Kees Cook <keescook@chromium.org>
Date:   Wed, 28 Mar 2018 04:24:14 -0700
Message-ID: <CAGXu5jLmyp4Q9VeP-F3N2SJuUxPpo3=2WTUC4vRLX348FwrtUQ@mail.gmail.com>
Subject: Re: [PATCH v2 15/21] gcov: remove CONFIG_GCOV_FORMAT_AUTODETECT
To:     Masahiro Yamada <yamada.masahiro@socionext.com>
Cc:     linux-kbuild <linux-kbuild@vger.kernel.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Ulf Magnusson <ulfalizer@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        "Luis R . Rodriguez" <mcgrof@kernel.org>,
        Nicolas Pitre <nico@linaro.org>,
        Peter Oberparleiter <oberpar@linux.vnet.ibm.com>,
        LKML <linux-kernel@vger.kernel.org>
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On Mon, Mar 26, 2018 at 10:29 PM, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
> CONFIG_GCOV_FORMAT_AUTODETECT compiles either gcc_3_4.c or gcc_4_7.c
> according to your GCC version.
>
> We can achieve the equivalent behavior by setting reasonable dependency
> with the knowledge of the compiler version.
>
> If GCC older than 4.7 is used, GCOV_FORMAT_3_4 is the default, but users
> are still allowed to select GCOV_FORMAT_4_7 in case the newer format is
> back-ported.
>
> On the other hand, If GCC 4.7 or newer is used, there is no reason to
> use GCOV_FORMAT_3_4, so it should be hidden.
>
> If you down-grade your compiler GCC 4.7 or older, oldconfig/syncconfig
> will display a prompt for the choice because GCOV_FORMAT_3_4 becomes
> visible as a new symbol.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

-- 
Kees Cook
Pixel Security