Messages in this thread | | | Date | Wed, 24 Mar 2010 11:53:13 -0700 | From | David Daney <> | Subject | Re: [PATCH] [RFC] #define __BYTE_ORDER |
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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
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