Date: Sun, 29 May 2005 11:29:43 -0700 From: Kris Kennaway <kris@obsecurity.org> To: "Anthony M. Agelastos" <iqgrande@gmail.com> Cc: freebsd-questions@freebsd.org Subject: Re: Kernel Optimizations Regarding SSE Message-ID: <20050529182942.GB15632@xor.obsecurity.org> In-Reply-To: <2F8EA84E-D7CE-4B5E-917D-3412D1077DA8@gmail.com> References: <2F8EA84E-D7CE-4B5E-917D-3412D1077DA8@gmail.com>
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[-- Attachment #1 --] On Sun, May 29, 2005 at 10:48:20AM -0400, Anthony M. Agelastos wrote: > Hello all, > > I am, as we converse, rebuilding world to 5-STABLE (from 5.4-STABLE 3 > weeks ago). This is the first time that I am building a custom kernel > and it only deviates from GENERIC in that I only have > > cpu I686_CPU (without the I586 and I486 that were there from > GENERIC) > > and I added > > option CPU_ENABLE_SSE (per the Handbook's suggestion for Video > Playback) > > That is it. In watching the compile of the new kernel, I notice that > just about every cc command has the options: > > -mno-mmx -mno-3dnow -mno-sse -mno-sse2 > > Is it me, or does those flags appear to be turning off the very thing > I wanted turned on (to turn it on, wouldn't it be -mmmx -m3dnow -msse > -msse2)? You misunderstand what the option does. It allows user code to use SSE, it doesn't cause SSE to be magically used in the kernel. Indeed, this is not feasible; please search the mailing list archives for extensive discussion of this issue. Kris [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (FreeBSD) iD8DBQFCmgoWWry0BWjoQKURAvUUAJ90BzdhDrqZLZBzwUUfKL+u1Aqu+ACgvfBD L9LPwwwYqabgJBqsFAKH+Ps= =yMua -----END PGP SIGNATURE-----
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