linux-kernel - Re: [PATCH 1/7] Compiler Attributes: remove unused attributes

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Date:   Fri, 31 Aug 2018 22:23:21 +0200
From:   Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Joe Perches <joe@...ches.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Eli Friedman <efriedma@...eaurora.org>,
        Christopher Li <sparse@...isli.org>,
        Kees Cook <keescook@...omium.org>,
        Ingo Molnar <mingo@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg KH <gregkh@...uxfoundation.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Dominique Martinet <asmadeus@...ewreck.org>
Subject: Re: [PATCH 1/7] Compiler Attributes: remove unused attributes

On Fri, Aug 31, 2018 at 8:43 PM, Nick Desaulniers
<ndesaulniers@...gle.com> wrote:
> On Fri, Aug 31, 2018 at 10:28 AM Joe Perches <joe@...ches.com> wrote:
>>
>> On Fri, 2018-08-31 at 19:05 +0200, Miguel Ojeda wrote:
>> > __optimize and __deprecate_for_modules are unused in
>> > the whole kernel tree. Simply drop them.
>>
>> Nice series, thanks Miguel.
>>
>> It'd be good to have a cover letter for the series.
>>
>> And I believe there should be the equivalent of:
>>
>> #if GCC_VERSION < 40600
>> # error Sorry, your compiler is too old - please upgrade it.
>> #endif
>>
>> for compiler-intel.h and compiler-clang.h so that
>> each supported compiler minimum version is checked.
>>
>> Is it clang > 13 and icc > 3 ?
>
> Eh, I'm not sure I want to commit yet to a specific minimal version of
> Clang.  Right now, we're fixing things so depending on arch's and
> configs, the answer might be Top of Tree clang builds.  For Pixel, we
> shipped with Clang-4, but pretty quickly we needed Clang-5.
> https://lkml.org/lkml/2017/11/22/943
>
> I had sent patches previously for detecting clang version from the C
> preprocessor, maybe I should dust those off, then commit to clang 5.

In my opinion, even if you require clang 7, that is fine, as long as
we get a working build mainlined.

By the way, I am testing the series with clang 8 (2018-08-14) (after
reverting e501ce957a78), and it seems to work. Hopefully that makes
you happy! ;-)

>
> I don't think minimal supported versions are required for these clean
> ups, and would not block these patches from landing on that.
>
> Also, haven't found anyone using ICC yet to comment on minimal version
> requirements.

For clang, by the way, __naked should go out of -gcc.h. I guess that
is breaking ARM clang builds at the moment (didn't check)? I will
include the move for v3.

Cheers,
Miguel