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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Tue, 21 Aug 2018 10:00:32 -0700
Message-ID: <CAKwvOdkLGhdQxx3oV=R2kv290NOv_w8qQ_yHWCVpvmofp7+ivQ@mail.gmail.com>
Subject: Re: [PATCH] compiler-gcc: get back Clang build
To:     joe@perches.com
Cc:     asmadeus@codewreck.org,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Kees Cook <keescook@chromium.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Arnd Bergmann <arnd@arndb.de>, dwmw@amazon.co.uk,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Will Deacon <will.deacon@arm.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
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On Tue, Aug 21, 2018 at 9:45 AM Joe Perches <joe@perches.com> wrote:
>
> On Tue, 2018-08-21 at 09:32 -0700, Nick Desaulniers wrote:
> > On Tue, Aug 21, 2018 at 5:38 AM Dominique Martinet
> > <asmadeus@codewreck.org> wrote:
> > >
> > > Nick Desaulniers Aug. 21, 2018, 8:09 a.m. UTC:
> > > > Thanks for noticing, and sending this patch.  I'm happy to see others
> > > > testing with Clang.  I noticed this too near the end of the day
> > > > https://github.com/ClangBuiltLinux/linux/issues/27.
> > >
> > > FWIW libbcc so many BPF users also use clang, so this has more impact
> > > than just testing to build linux with clang (not that this would be any
> > > reason to delay fixing either way)
> > >
> > > I would tend to agree havin a compiler-common + make clang/intel not
> > > include compiler-gcc would probably be best in the long run but we might
> > > want a quick fix for 4.19 meanwhile..
> >
> > That's fair. SOP here is quick (full) revert, then come up with a
> > better fix.  And I do prefer Masahiro's partial revert to a full
> > revert of Joe's patch.  That will give us more time to develop the
> > proper fix rather than rush.  I'll try to see how we can more properly
> > split the compiler specific headers.
> >
> > Tested with gcc-7 and clang-8.
>
> clang-8? Isn't the latest officlal clang 6.0.1 ?

Yes, but I have a local llvm tree that I work out of, that's in my
$PATH, so my version of clang is never too far behind Top of Tree.
For android, we're using clang-5, but currently staging an upgrade to
clang 6.0.1.

> So if something other than 6.0.x is required,
> then some additional check should probably be
> added to compiler-clang.h as well.
>

Sure, but that doesn't need to go in Mashiro's patch today.  That can
wait for a proper separation between compiler headers where we can
then implement improved version checks.

-- 
Thanks,
~Nick Desaulniers