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Re: [PATCH] MIPS: Define __arch_swab64 for all mips r2 cpus (v2).

To: "Maciej W. Rozycki" <macro@linux-mips.org>
Subject: Re: [PATCH] MIPS: Define __arch_swab64 for all mips r2 cpus (v2).
From: Ralf Baechle <ralf@linux-mips.org>
Date: Wed, 1 Jul 2009 19:40:27 +0100
Cc: David Daney <ddaney@caviumnetworks.com>, linux-mips@linux-mips.org
In-reply-to: <alpine.LFD.2.00.0907010234320.23134@eddie.linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <1246294455-26866-1-git-send-email-ddaney@caviumnetworks.com> <20090629193454.GA23430@linux-mips.org> <alpine.LFD.2.00.0907010132500.23134@eddie.linux-mips.org> <4A4AB845.1030906@caviumnetworks.com> <alpine.LFD.2.00.0907010234320.23134@eddie.linux-mips.org>
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User-agent: Mutt/1.5.18 (2008-05-17)
On Wed, Jul 01, 2009 at 02:36:31AM +0100, Maciej W. Rozycki wrote:

> > The problem with CPU_MIPS64_R2 in the kernel is that it means two unrelated
> > things:
> > 
> > 1) The cpu can execute all mips64r2 ISA instructions.
> > 
> > 2) The cpu requires that all worse case cache and execution hazards are
> > handled.
> > 
> > In the case of the Octeon processors, #1 is true, but we can get better
> > performance by omitting many of the hazard barriers because they are 
> > unneeded.
> 
>  Which is why I think a split of the semantics would be a good idea.

That's the idea since a long time.  There are far less uses of CONFIG_CPU_*
than there used to be historically - and usually they're a bug or at least
should be considered one.

  Ralf

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