From owner-freebsd-stable Sun Jul 28 21:15: 6 2002 Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 903E537B400 for ; Sun, 28 Jul 2002 21:15:03 -0700 (PDT) Received: from InterJet.dellroad.org (adsl-63-194-81-26.dsl.snfc21.pacbell.net [63.194.81.26]) by mx1.FreeBSD.org (Postfix) with ESMTP id 095D543E31 for ; Sun, 28 Jul 2002 21:15:03 -0700 (PDT) (envelope-from archie@dellroad.org) Received: from arch20m.dellroad.org (arch20m.dellroad.org [10.1.1.20]) by InterJet.dellroad.org (8.9.1a/8.9.1) with ESMTP id VAA14041; Sun, 28 Jul 2002 21:11:46 -0700 (PDT) Received: (from archie@localhost) by arch20m.dellroad.org (8.11.6/8.11.6) id g6T4AU910168; Sun, 28 Jul 2002 21:10:30 -0700 (PDT) (envelope-from archie) From: Archie Cobbs Message-Id: <200207290410.g6T4AU910168@arch20m.dellroad.org> Subject: Re: Is use of -O2 still deprecated for buildworld in -stable? In-Reply-To: <20020727191945.A10231@lava.net> "from Clifton Royston at Jul 27, 2002 07:19:45 pm" To: Clifton Royston Date: Sun, 28 Jul 2002 21:10:29 -0700 (PDT) Cc: freebsd-stable@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL88 (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Clifton Royston writes: > My understanding is that whether or not -O2 *should* produce exactly > equivalent code to -O, there are recurrent reports of people having > trouble doing a buildworld with -O2 in -stable or in 4.x release > trains, where their problems go away when they revert back to -O. In > this case, we simply shouldn't be using it on production servers. I'm > using it on my home machines (-O2 for world, -O for kernel) but they > has altogether different needs for reliability. I've wondered about this a lot myself and never seen a clear answer. My best guess as to what's going on is that the FreeBSD kernel contains some (broken?) asm() statements that cause incorrect code to be generated when -O2 is used, but not when -O is used. This would explain how -O2 could cause FreeBSD to not work without there actually being a bug in gcc causing it. -Archie __________________________________________________________________________ Archie Cobbs * Packet Design * http://www.packetdesign.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message