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Date: Tue, 29 Aug 2006 17:20:55 +0100
From: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: Why Semaphore Hardware-Dependent?
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To: Christoph Lameter <clameter@sgi.com>
Cc: David Howells <dhowells@redhat.com>, Nick Piggin <nickpiggin@yahoo.com.au>, Arjan van de Ven <arjan@infradead.org>, Dong Feng <middle.fengdong@gmail.com>, ak@suse.de, Paul Mackerras <paulus@samba.org>, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
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On Tue, Aug 29, 2006 at 08:56:36AM -0700, Christoph Lameter wrote:

> > Because i386 (and x86_64) can do better by using XADDL/XADDQ.
> 
> And Ia64 would like to use fetchadd....
> 
> > CMPXCHG is not available on all archs, and may not be implemented on all archs
> > through other atomic instructions.
> 
> Which arches do not support cmpxchg?

MIPS, Alpha - probably any pure RISC load/store architecture.

  Ralf