lkml.org 
[lkml]   [2010]   [Mar]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] [RFC] #define __BYTE_ORDER
On 03/24/2010 11:37 AM, Geert Uytterhoeven 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.
>

I have stumbled on this issue as well.

However, consider this:

If you make such a change, then you will start to see:

#if __BYTE_ORDER == __BIG_ENDIAN

appearing in kernel source code. Do we want two different endian
checking idioms in the kernel? Or would it be just a single idiom, but
one that is different than the status quo?

The only time I can see that it makes a difference is if you want to
share things like driver source code files between in-kernel drivers and
userspace. A discussion of which, would probably provoke much discussion.

David Daney




\
 
 \ /
  Last update: 2010-03-24 19:55    [W:0.045 / U:1.944 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site