Re: amd64 default CFLAGS

From: Kris Kennaway <kris_at_FreeBSD.org>
Date: Wed, 9 Mar 2005 17:01:00 +0000
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
Received on Wed Mar 09 2005 - 16:01:00 UTC

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