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Date: Wed, 24 Mar 2010 11:51:12 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] [RFC] #define __BYTE_ORDER
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On Wed, 24 Mar 2010 19:37:36 +0100
Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> On Wed, Mar 24, 2010 at 19:21, Andrew Morton <akpm@linux-foundation.org> wrote:
> > On Wed, 17 Mar 2010 19:10:55 +0100
> > Joakim Tjernlund <Joakim.Tjernlund@transmode.se> wrote:
> >
> >> Linux does not define __BYTE_ORDER in its endian header files
> >> which makes some header files bend backwards to get at the
> >> current endian. Lets #define __BYTE_ORDER in big_endian.h/litte_endian.h
> >> to make it easier for header files that are used in user space too.
> >
> > I don't get it. __Why not nuke __BYTE_ORDER altogether and do `#ifdef
> > __LITTLE_ENDIAN' and `#ifdef __BIG_ENDIAN' everywhere?
> 
> Because in userspace the convention is that
>   1. _both_ __LITTLE_ENDIAN and __BIG_ENDIAN are defined,
>   2. you have to test for e.g. __BYTE_ORDER == __BIG_ENDIAN.

umph.  We don't _have_ to copy userspace, and removing __BYTE_ORDER
altogether makes the kernel cleaner and simpler.

But if we did that, we shouldn't have used the same symbols as
userspace.  Sigh.