linux-kernel - Re: [patch 01/23] Fall back on interrupt disable in cmpxchg8b on 80386 and 80486

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Message-ID: <Pine.LNX.4.64.0708121750090.28963@fbirervta.pbzchgretzou.qr>
Date:	Sun, 12 Aug 2007 17:51:18 +0200 (CEST)
From:	Jan Engelhardt <jengelh@...putergmbh.de>
To:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
cc:	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Christoph Lameter <clameter@....com>, mingo@...hat.com
Subject: Re: [patch 01/23] Fall back on interrupt disable in cmpxchg8b on
 80386 and 80486


On Aug 12 2007 10:54, Mathieu Desnoyers wrote:

>Date: Sun, 12 Aug 2007 10:54:35 -0400
>From: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
>To:  <akpm@...ux-foundation.org>,  <linux-kernel@...r.kernel.org>
>Cc: Christoph Lameter <clameter@....com>,
>    Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,  <mingo@...hat.com>
>Subject: [patch 01/23] Fall back on interrupt disable in cmpxchg8b on 80386 and
>     80486
>
>Actually, on 386, cmpxchg and cmpxchg_local fall back on
>cmpxchg_386_u8/16/32: it disables interruptions around non atomic
>updates to mimic the cmpxchg behavior.
>
>The comment:
>/* Poor man's cmpxchg for 386. Unsuitable for SMP */
>
>already present in cmpxchg_386_u32 tells much about how this cmpxchg
>implementation should not be used in a SMP context. However, the cmpxchg_local
>can perfectly use this fallback, since it only needs to be atomic wrt the local
>cpu.
>
>This patch adds a cmpxchg_486_u64 and uses it as a fallback for cmpxchg64
>and cmpxchg64_local on 80386 and 80486.

hm, but why is it called cmpxchg_486 when the other functions are called
cmpxchg_386?


	Jan
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