Date: Tue, 1 May 2001 13:53:26 -0700 From: Kris Kennaway <kris@obsecurity.org> To: Steve Roome <stephen_roome@yahoo.com> Cc: freebsd-questions@freebsd.org Subject: Re: CPUTYPE, Athlons, 686 or pentium ?? Message-ID: <20010501135326.A11314@xor.obsecurity.org> In-Reply-To: <20010501191111.A93807@pepcross.demon.co.uk>; from stephen_roome@yahoo.com on Tue, May 01, 2001 at 07:11:11PM %2B0100 References: <20010501191111.A93807@pepcross.demon.co.uk>
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--Kj7319i9nmIyA2yE Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, May 01, 2001 at 07:11:11PM +0100, Steve Roome wrote: > Noting the new(ish) CPUTYPE option in make.conf I see that k7 defaults > to setting options for k6 in gcc. (just made world for 4.3-Release > using CPUTYPE=3Dk7) >=20 > I assume this was carefully thought out and that it possibly shouldn't > default to optimising for pentiumpro instead. (or should it, frankly I > don't understand why the choice was k6 opts instead of ppro opts, I > assume k6 opts work better, but I've not tested it in depth yet.) For the athlon, the best optimization options for the current version of gcc are believed to be the k6 setting. Future versions of gcc will apparently optimize specifically for the k7. This hasn't been extensively benchmarked, so you might be able to prove me wrong -- so feel free to test this. > However.. in the kernel config file I've always specified the athlon > as a 686 class CPU. This seems inconsistent. Simple: there's no AMD-tuned asm code in the kernel, so the next best thing is the pentium-pro class optimizations (i686) > Or should my kernel config have I586_CPU instead of I686_CPU. > (I assume it wouldn't boot that way, but I've not tried it.) It would work fine; they're backwards compatible. I don't know what the performance penalty is. Kris --Kj7319i9nmIyA2yE Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.5 (FreeBSD) Comment: For info see http://www.gnupg.org iD8DBQE67yJGWry0BWjoQKURAlj6AJ4kg1mH1+CJUtUIUsQV1oCheGI2egCfXajb frXIK5wJoWDdYNfjj+p9uKc= =0Xhf -----END PGP SIGNATURE----- --Kj7319i9nmIyA2yE-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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