From owner-freebsd-stable Mon Dec 11 7:32:49 2000 From owner-freebsd-stable@FreeBSD.ORG Mon Dec 11 07:32:46 2000 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from veldy.net (w028.z064001117.msp-mn.dsl.cnc.net [64.1.117.28]) by hub.freebsd.org (Postfix) with ESMTP id 6E25B37B400 for ; Mon, 11 Dec 2000 07:32:46 -0800 (PST) Received: from HP2500B (veldy.net [64.1.117.28]) by veldy.net (Postfix) with SMTP id B5A318C13; Mon, 11 Dec 2000 09:32:23 -0600 (CST) Message-ID: <00af01c06387$1ecb5230$9c29680a@tgt.com> From: "Thomas T. Veldhouse" To: "Mark Powell" Cc: References: Subject: Re: Different gcc optimisations cause IP packet CRC problems Date: Mon, 11 Dec 2000 09:29:14 -0600 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG I generally don't compile the kernel with any optimizations except "-O -pipe". I never have a problem - and I don't have any performance differences that have been noticable. Tom Veldhouse veldy@veldy.net ----- Original Message ----- From: "Mark Powell" To: Sent: Monday, December 11, 2000 9:24 AM Subject: Different gcc optimisations cause IP packet CRC problems > Hi, > On a PIII 600E, compiling a week old 4.2S kernel with the following > options: > > -O2 -fomit-frame-pointer -mpentium -march=pentium -pipe > > Cause the kernel to produce TCP CRC errors when talking to certain IP > addresses. It generally seemed to get the 2nd octet of the CRC out by one > i.e. 0xb9f7 became 0xbaf7 etc. > I originally did this, because I was using this fastish machine to > remake world for another P166 machine. I forgot to change it back and > accidentally recompiled it's own kernel with the above settings. > This problem was fixed by simply changing the gcc optimisation to the > correct CPU type: > > -O2 -fomit-frame-pointer -mpentiumpro -march=pentiumpro -pipe > > However, shouldn't the PIII be backwards compatible with any Pentium code? > Or are there some incorrect assumptions made in the CRC generation code? > Cheers. > > BTW Where in the source is the CRC generated? > > Mark Powell - UNIX System Administrator - The University of Salford > Academic Information Services, Clifford Whitworth Building, > Salford University, Manchester, M5 4WT, UK. > Tel: +44 161 295 5936 Fax: +44 161 295 5888 www.pgp.com for PGP key > > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-stable" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message