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

[H. Peter Anvin]

Arjan van de Ven wrote:
> On Tue, 02 Oct 2007 18:08:32 +0400
> Kirill Korotaev <dev@xxxxxxxxxx> 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
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