From: "H. Peter Anvin" <hpa@zytor.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Kirill Korotaev <dev@openvz.org>, Andrew Morton <akpm@osdl.org>,
Andi Kleen <ak@suse.de>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
devel@openvz.org
Subject: Re: [PATCH] mark read_crX() asm code as volatile
Date: Tue, 02 Oct 2007 12:21:22 -0700 [thread overview]
Message-ID: <47029A32.7010803@zytor.com> (raw)
In-Reply-To: <20071002082856.3c478e66@laptopd505.fenrus.org>
Arjan van de Ven wrote:
> On Tue, 02 Oct 2007 18:08:32 +0400
> Kirill Korotaev <dev@openvz.org> wrote:
>
>> Some gcc versions (I checked at least 4.1.1 from RHEL5 & 4.1.2 from
>> gentoo) can generate incorrect code with read_crX()/write_crX()
>> functions mix up, due to cached results of read_crX().
>>
>
> I'm not so sure volatile is the right answer, as compared to giving the
> asm more strict contraints....
>
> asm volatile tends to mean something else than "the result has
> changed"....
>
One of the aspect of volatility is "the result will change in ways you
(gcc) just don't understand."
-hpa
next prev parent reply other threads:[~2007-10-02 19:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-02 14:08 [PATCH] mark read_crX() asm code as volatile Kirill Korotaev
2007-10-02 14:17 ` Andi Kleen
2007-10-02 15:28 ` Arjan van de Ven
2007-10-02 18:27 ` Chuck Ebbert
2007-10-02 12:14 ` Nick Piggin
2007-10-03 6:18 ` H. Peter Anvin
2007-10-02 15:49 ` Nick Piggin
2007-10-03 8:45 ` Andi Kleen
2007-10-02 19:21 ` H. Peter Anvin [this message]
2007-10-03 8:25 ` Kirill Korotaev
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