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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Wed, 10 Apr 2019 21:00:52 +0200
Message-ID: <CAK8P3a3ytjz5KarSPyk4G=HOGopBMN65j0eYaWZanUbGoe=wXw@mail.gmail.com>
Subject: Re: [PATCH 02/12] s390: don't build vdso32 with clang
To:     Nick Desaulniers <ndesaulniers@google.com>
Cc:     Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        clang-built-linux@googlegroups.com,
        Nathan Chancellor <natechancellor@gmail.com>,
        linux-s390 <linux-s390@vger.kernel.org>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Ursula Braun <ubraun@linux.ibm.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        LKML <linux-kernel@vger.kernel.org>
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On Wed, Apr 10, 2019 at 6:26 PM 'Nick Desaulniers' via Clang Built
Linux <clang-built-linux@googlegroups.com> wrote:
>
> On Mon, Apr 8, 2019 at 2:27 PM Arnd Bergmann <arnd@arndb.de> wrote:
> >
> > clang does not support 31 bit object files on s390, so skip
> > the 32-bit vdso here, and only build it when using gcc to compile
> > the kernel.
>
> What's the build failure?  Would you mind filing a bug against LLVM's
> issue tracker for it, please?

As far as I can tell, llvm does only supports 64-bit output for s390, so this
is not a bug but rather a missing feature that seems highly unlikely to
ever get added.

32-bit (31-bit) mode on s390 is only used for very old existing binaries,
and the vdso support is optional there.

      Arnd