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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Sun, 11 Feb 2018 11:42:44 -0800
Message-ID: <CA+55aFyj-CfvHoRtoDVHarMOcoDjyH5b9E6QecW7yHZo-Ok31A@mail.gmail.com>
Subject: Re: [RFC PATCH 4/7] kconfig: support new special property shell=
To:     Kees Cook <keescook@chromium.org>
Cc:     Ulf Magnusson <ulfalizer@gmail.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nicolas Pitre <nicolas.pitre@linaro.org>,
        "Luis R . Rodriguez" <mcgrof@suse.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Pavel Machek <pavel@ucw.cz>,
        linux-s390 <linux-s390@vger.kernel.org>,
        Jiri Kosina <jkosina@suse.cz>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@kernel.org>,
        "Van De Ven, Arjan" <arjan.van.de.ven@intel.com>,
        Arnd Bergmann <arnd@arndb.de>
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On Sun, Feb 11, 2018 at 10:13 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> That actually sounds like we could just
>
>  (a) make gcc 4.5 be the minimum required version
>
>  (b) actually error out if we find a bad compiler

Just to explain why that's different from what we do not (apart from
the "error out" thing to actually actively discourage broken
compilers): it simplifies things if we can just add a trivial check as
part of the build process rather than as part of the configuration.

If we don't have to make it part of the configuration, we can use all
the normal Kconfig rules and build rules, and then we can add the
error check to any number of places where we already do various object
file munging.

For example, it would be pretty trivial to do the "check that there's
the right segment access" as part of link-vmlinux.sh or something.

And that would allow us to just use all the regular config
infrastructure, including the (hopefully by 4.17) "cc-option" thing at
Kconfig time.

             Linus