linux-kernel - Re: K8, EFFICEON and CORE2 support the cmovxx instructions.

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Message-ID: <20080315211125.GB13012@1wt.eu>
Date:	Sat, 15 Mar 2008 22:11:25 +0100
From:	Willy Tarreau <w@....eu>
To:	Alexander van Heukelum <heukelum@...tmail.fm>
Cc:	"H. Peter Anvin" <hpa@...or.com>,
	Alexander van Heukelum <heukelum@...lshack.com>,
	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: K8, EFFICEON and CORE2 support the cmovxx instructions.

On Sat, Mar 15, 2008 at 10:06:32PM +0100, Alexander van Heukelum wrote:
> > > I'm quite sure that K8, EFFICEON and CORE2 support HAVE_CMOV, but
> > > they did not set X86_CMOV.
> > > 
> > 
> > Crusoe has CMOV as well.

So does GEODE_LX BTW

> I believe you... and the Makefile_32.cpu: it gets a -march=i686. I
> also found out that I missed X86_ELAN, which is treated as a i486.
> 
> Also, MGEODE_LX does not get any optimization flags. I think that
> is unintentional, but what should they be?

in my experience (on user-space code), optimizing for "i586" gives
good results. However, the cache is small, so everything which can
reduce code size (especially loop/jump/function alignment) is worth
checking.

Regards,
Willy

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