linux-kernel - Re: [PATCH] mark read_crX() asm code as volatile

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Date:	Tue, 2 Oct 2007 08:28:56 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Kirill Korotaev <dev@...nvz.org>
Cc:	Andrew Morton <akpm@...l.org>, Andi Kleen <ak@...e.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	devel@...nvz.org
Subject: Re: [PATCH] mark read_crX() asm code as volatile

On Tue, 02 Oct 2007 18:08:32 +0400
Kirill Korotaev <dev@...nvz.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"....

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