From: Arnd Bergmann <arnd@arndb.de>
To: "Guan Xuetao" <gxt@mprc.pku.edu.cn>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: about __BITS_PER_LONG
Date: Mon, 11 Apr 2011 17:24:57 +0200 [thread overview]
Message-ID: <201104111724.57607.arnd@arndb.de> (raw)
In-Reply-To: <003f01cbf81a$f48cfdf0$dda6f9d0$@mprc.pku.edu.cn>
On Monday 11 April 2011, Guan Xuetao wrote:
> --- a/include/asm-generic/bitsperlong.h
> +++ b/include/asm-generic/bitsperlong.h
> @@ -9,7 +9,11 @@
> * to decide it, but rather check a compiler provided macro.
> */
> #ifndef __BITS_PER_LONG
> -#define __BITS_PER_LONG 32
> +# ifdef CONFIG_64BIT
> +# define __BITS_PER_LONG 64
> +# else
> +# define __BITS_PER_LONG 32
> +# endif /* CONFIG_64BIT */
> #endif
>
Unfortunately, this does not work, because the __BITS_PER_LONG definition is meant
for user space. You have to make this depend on a preprocessor macro that
is provided by the compiler based on the command line switches (e.g. -m64) that
a use could pass to the compiler.
In user space, the CONFIG_* symbols are meaningless.
Arnd
next prev parent reply other threads:[~2011-04-11 15:25 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-11 7:34 about __BITS_PER_LONG Guan Xuetao
2011-04-11 15:24 ` Arnd Bergmann [this message]
2011-04-12 1:24 ` Guan Xuetao
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