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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--NMuMz9nt05w80d4+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, May 29, 2005 at 10:48:20AM -0400, Anthony M. Agelastos wrote: > Hello all, >=20 > I am, as we converse, rebuilding world to 5-STABLE (from 5.4-STABLE 3 =20 > weeks ago). This is the first time that I am building a custom kernel =20 > and it only deviates from GENERIC in that I only have >=20 > cpu I686_CPU (without the I586 and I486 that were there from =20 > GENERIC) >=20 > and I added >=20 > option CPU_ENABLE_SSE (per the Handbook's suggestion for Video =20 > Playback) >=20 > That is it. In watching the compile of the new kernel, I notice that =20 > just about every cc command has the options: >=20 > -mno-mmx -mno-3dnow -mno-sse -mno-sse2 >=20 > Is it me, or does those flags appear to be turning off the very thing =20 > I wanted turned on (to turn it on, wouldn't it be -mmmx -m3dnow -msse =20 > -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 --NMuMz9nt05w80d4+ Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (FreeBSD) iD8DBQFCmgoWWry0BWjoQKURAvUUAJ90BzdhDrqZLZBzwUUfKL+u1Aqu+ACgvfBD L9LPwwwYqabgJBqsFAKH+Ps= =yMua -----END PGP SIGNATURE----- --NMuMz9nt05w80d4+--
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