Re: bit fields && data tearing
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- To: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
- Subject: Re: bit fields && data tearing
- From: Michael Cree <mcree@xxxxxxxxxxxx>
- Date: Sat, 6 Sep 2014 08:39:51 +1200
- Cc: Marc Gauthier <marc@xxxxxxxxxxx>, "paulmck@xxxxxxxxxxxxxxxxxx" <paulmck@xxxxxxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>, David Laight <David.Laight@xxxxxxxxxx>, Jakub Jelinek <jakub@xxxxxxxxxx>, "linux-arch@xxxxxxxxxxxxxxx" <linux-arch@xxxxxxxxxxxxxxx>, Tony Luck <tony.luck@xxxxxxxxx>, "linux-ia64@xxxxxxxxxxxxxxx" <linux-ia64@xxxxxxxxxxxxxxx>, Oleg Nesterov <oleg@xxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, Paul Mackerras <paulus@xxxxxxxxx>, "linuxppc-dev@xxxxxxxxxxxxxxxx" <linuxppc-dev@xxxxxxxxxxxxxxxx>, Miroslav Franc <mfranc@xxxxxxxxxx>, Richard Henderson <rth@xxxxxxxxxxx>, "linux-alpha@xxxxxxxxxxxxxxx" <linux-alpha@xxxxxxxxxxxxxxx>
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- User-agent: Mutt/1.5.23 (2014-03-12)
On Fri, Sep 05, 2014 at 04:14:48PM -0400, Peter Hurley wrote:
> Second, in the body of the document:
>
> "The Linux kernel no longer supports pre-EV56 Alpha CPUs, because these
> older CPUs _do not provide_ atomic one-byte and two-byte loads and stores."
Let's be clear here, the pre-EV56 Alpha CPUs do provide an atomic
one-byte and two-byte load and store; it's just that one must use
locked load and store sequences to achieve atomicity. The point,
I think, is that the pre-EV56 Alpha CPUs provide non-atomic one-byte
and two-byte load and stores as the norm, and that is the problem.
Cheers
Michael.
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