linux-kernel - Re: [PATCH 2/2] include: warn for inconsistent endian config definition

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Date:   Fri, 9 Jun 2017 09:05:57 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Babu Moger <babu.moger@...cle.com>
Cc:     Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Stafford Horne <shorne@...il.com>,
        "James E.J. Bottomley" <jejb@...isc-linux.org>,
        Helge Deller <deller@....de>,
        "David S. Miller" <davem@...emloft.net>,
        Al Viro <viro@...iv.linux.org.uk>,
        Michael Ellerman <mpe@...erman.id.au>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Max Filippov <jcmvbkbc@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        uclinux-h8-devel@...ts.sourceforge.jp,
        "Linux/m68k" <linux-m68k@...r.kernel.org>,
        openrisc@...ts.librecores.org,
        Parisc List <linux-parisc@...r.kernel.org>,
        sparclinux <sparclinux@...r.kernel.org>
Subject: Re: [PATCH 2/2] include: warn for inconsistent endian config definition

On Fri, Jun 9, 2017 at 12:17 AM, Babu Moger <babu.moger@...cle.com> wrote:
> Display warning if CPU_BIG_ENDIAN is not defined on big endian
> architecture and also warn if it defined on little endian architectures.
>
> We have seen some generic code(for example code include/asm-generic/qrwlock.h)
> uses CONFIG_CPU_BIG_ENDIAN to decide the endianess.

That example is IMHO the least harmful, as qrwlock must be selected explicitly
by the architecture.

The uses in

    drivers/of/base.c
    drivers/of/fdt.c
    drivers/tty/serial/earlycon.c
    drivers/tty/serial/serial_core.c

are more dangerous, and may have bitten people already.
In addition, people may have worked around them in DT, so this series may
actually introduce regressions.

> Here is the original discussion
> http://www.spinics.net/lists/devicetree/msg178101.html
>
> Signed-off-by: Babu Moger <babu.moger@...cle.com>
> Suggested-by: Arnd Bergmann <arnd@...db.de>

Hmm, the link above refers to a mail from me? ;-)

Acked-by: Geert Uytterhoeven <geert@...ux-m68k.org>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds