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From: Richard Henderson <rth@twiddle.net>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andrew Morton <akpm@zip.com.au>,
	linux-kernel@vger.kernel.org, torvalds@transmeta.com,
	kuznet@ms2.inr.ac.ru
Subject: Re: [PATCH] per-cpu areas for 2.5.3-pre6
Date: Wed, 30 Jan 2002 00:22:04 -0800	[thread overview]
Message-ID: <20020130002204.A4480@are.twiddle.net> (raw)
In-Reply-To: <3C57207E.28598C1F@zip.com.au> <E16VivB-0005sI-00@wagner.rustcorp.com.au> <3C57430B.8B6DFD9F@zip.com.au> <20020130130026.13803fda.rusty@rustcorp.com.au>
In-Reply-To: <20020130130026.13803fda.rusty@rustcorp.com.au>; from rusty@rustcorp.com.au on Wed, Jan 30, 2002 at 01:00:26PM +1100

On Wed, Jan 30, 2002 at 01:00:26PM +1100, Rusty Russell wrote:
> +#define per_cpu(var, cpu)						  \
> +(*((__typeof__(&var))((void *)&var + per_cpu_offset(cpu))))

Have we already forgotten the ppc reloc flamefest?  Better
written as

#define per_cpu(var, cpu)					\
  ({ __typeof__(&(var)) __ptr;					\
     __asm__ ("" : "=g"(__ptr)					\
	      : "0"((void *)&(var) + per_cpu_offset(cpu)));	\
     *__ptr; })

> +/* Created by linker magic */
> +extern char __per_cpu_start, __per_cpu_end;
[...]
> +	per_cpu_size = ((&__per_cpu_end - &__per_cpu_start) + PAGE_SIZE-1)

Will fail on targets (e.g. alpha and mips) that have a notion of a
"small data area" that can be addressed with special relocs.

Better written as

  extern char __per_cpu_start[], __per_cpu_end[];
  per_cpu_size = (__per_cpu_end - __per_cpu_start) ...


r~

  parent reply	other threads:[~2002-01-30  8:23 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-01-29  9:01 [PATCH] per-cpu areas for 2.5.3-pre6 Rusty Russell
2002-01-29  9:22 ` Andrew Morton
2002-01-29 22:09   ` Rusty Russell
2002-01-29 22:21     ` Andrew Morton
2002-01-30  0:48       ` Rusty Russell
2002-01-30  0:49         ` Andrew Morton
2002-01-30  2:00           ` Rusty Russell
2002-01-30  2:12             ` Linus Torvalds
2002-01-30  4:13               ` Rusty Russell
2002-01-30  8:22             ` Richard Henderson [this message]
2002-01-30 22:45               ` Rusty Russell
2002-01-31  5:49                 ` Richard Henderson
2002-02-01  8:56                   ` Rusty Russell
2002-02-01 16:52                     ` Richard Henderson
2002-01-29 23:17 ` Oliver Xymoron
2002-01-29 23:36   ` Linus Torvalds
2002-01-30  0:20     ` Oliver Xymoron
2002-01-30  0:44       ` Rusty Russell
2002-01-30  7:00         ` Oliver Xymoron
2002-01-30 19:43           ` Oliver Xymoron
2002-01-30 23:00             ` Rusty Russell

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