Date: Wed, 9 Mar 2005 17:01:00 +0000 From: Kris Kennaway <kris@FreeBSD.org> To: Divacky Roman <xdivac02@stud.fit.vutbr.cz> Cc: current@freebsd.org Subject: Re: amd64 default CFLAGS Message-ID: <20050309170100.GG50186@hub.freebsd.org> In-Reply-To: <20050309092749.GA72315@stud.fit.vutbr.cz> References: <20050309092749.GA72315@stud.fit.vutbr.cz>
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On Wed, Mar 09, 2005 at 10:27:49AM +0100, Divacky Roman wrote: > hi, > > why is it necessary (if its at all) to have this: > -mfpmath=387 -mno-sse -mno-sse2 -mno-mmx -mno-3dnow in default CFLAGS for amd64 > architecture? This is the default COPTFLAGS, not CFLAGS, right? You can't use special instructions like sse in the kernel because they require extra register state operations that would cost performance. Kris
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