Date: Wed, 21 Jan 2009 15:25:22 -0700
From: Grant Grundler <grundler@parisc-linux.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: David Miller <davem@davemloft.net>, jaswinder@kernel.org, mingo@elte.hu,
       x86@kernel.org, linux-kernel@vger.kernel.org,
       linux-parisc@vger.kernel.org
Subject: Re: Confusion in usr/include/asm-generic/fcntl.h
Message-ID: <20090121222522.GB15211@colo.lackof.org>
References: <1232496257.3123.19.camel@localhost.localdomain> <20090120.161626.93641145.davem@davemloft.net> <200901210124.26118.arnd@arndb.de>
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On Wed, Jan 21, 2009 at 01:24:25AM +0100, Arnd Bergmann wrote:
...
> > This file needs to test for 64-bit'ness using some non-CONFIG_*
> > test.  And the standard built-in CPP macros which can be used
> > to check for that are different on every platform.
> 
> I think we should simply define a macro for use in the kernel, e.g. in
> <asm/types.h>. There already is a BITS_PER_LONG macro in there, maybe
> we can add an exported __BITS_PER_LONG there that checks for the right
> macro on each architecture.

I'm pretty sure __LP64__ is the standard compiler defined macro
for 64-bit builds on most architectures.

> On parisc, there is a major confusion in this area, at some point, all
> checks for __LP64__ got replaced with CONFIG_64BIT there. While I have
> not understood what the problem with __LP64__ was,

IIRC, the problem with __LP64__ is it wasn't visible to the CONFIG
tool chains and dependencies. I believe that's fixed now and parisc
could deprecate use of CONFIG_64BIT if there is a strong preference
for __LP64__.

> the check for
> CONFIG_64BIT on parisc user space looks very wrong.

This shouldn't be exported to user space. Is that what you meant?
PA-RISC user space can currently only be 32-bit anyway.
So a 64-bit kernel will have to take that into consideration.

thanks,
grant
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