From: Brian Gerst <bgerst@didntduck.org>
To: Joseph Seigh <jseigh_02@xemaps.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: What does atomic_read actually do?
Date: Sat, 18 Dec 2004 16:03:57 -0500 [thread overview]
Message-ID: <41C49B3D.5040802@didntduck.org> (raw)
In-Reply-To: <opsi707edhs29e3l@grunion>
Joseph Seigh wrote:
> On Sat, 18 Dec 2004 20:54:40 +0100, Arjan van de Ven
> <arjan@infradead.org> wrote:
>
>> On Sat, 2004-12-18 at 14:20 -0500, Joseph Seigh wrote:
>>
>>> I mean atomic in the either old or new sense. I'm wondering what
>>> guarantees
>>> the atomicity. Not the C standard. I can see the gcc compiler uses
>>> a MOV
>>> instruction to load the atomic_t from memory which is guaranteed
>>> atomic by
>>> the architecture if aligned properly. But gcc does that for any old int
>>> as far as I can see, so why use atomic_read?
>>
>>
>> it does so on *x86
>
>
> Is this documented for gcc anywhere? Just because it does so doesn't
> mean it's guaranteed.
>
> Joe Seigh
ftp://download.intel.com/design/Pentium4/manuals/25366814.pdf
Chapter 7, section 1
--
Brian Gerst
next prev parent reply other threads:[~2004-12-18 21:04 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-12-18 16:23 What does atomic_read actually do? Joseph Seigh
2004-12-18 17:11 ` Paolo Ornati
2004-12-18 18:14 ` Joseph Seigh
2004-12-18 18:34 ` Arjan van de Ven
2004-12-18 19:20 ` Joseph Seigh
2004-12-18 19:39 ` Joe Korty
2004-12-18 19:54 ` Arjan van de Ven
2004-12-18 20:43 ` Joseph Seigh
2004-12-18 21:03 ` Brian Gerst [this message]
2004-12-19 22:21 ` Robert Love
2004-12-19 23:50 ` Joseph Seigh
2004-12-20 11:51 ` Arjan van de Ven
2004-12-20 12:52 ` Andrea Arcangeli
2004-12-20 20:51 ` Joseph Seigh
2004-12-18 20:47 ` Brian Gerst
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