From owner-freebsd-questions@FreeBSD.ORG Sun Sep 28 10:54:19 2003 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DFC1D16A4B3 for ; Sun, 28 Sep 2003 10:54:19 -0700 (PDT) Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101]) by mx1.FreeBSD.org (Postfix) with ESMTP id DE5C644025 for ; Sun, 28 Sep 2003 10:54:12 -0700 (PDT) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.12.9/8.12.9) id h8SHs6M3076555; Sun, 28 Sep 2003 12:54:06 -0500 (CDT) (envelope-from dan) Date: Sun, 28 Sep 2003 12:54:06 -0500 From: Dan Nelson To: Alex de Kruijff Message-ID: <20030928175405.GF25442@dan.emsphone.com> References: <20030928173759.GA16713@dds.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030928173759.GA16713@dds.nl> X-OS: FreeBSD 5.1-CURRENT X-message-flag: Outlook Error User-Agent: Mutt/1.5.4i cc: freebsd-questions@freebsd.org Subject: Re: Q: Compiles for wrong processor and it still worked X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 28 Sep 2003 17:54:20 -0000 In the last episode (Sep 28), Alex de Kruijff said: > I have compiles my world sources for the PIII processors. I have > recently discoverd that i have a number of PII processors. The compiled > code for PIII still works on them. I'm ammazed. :o Can anybody explain why? > > I include this in to /etc/make.conf 686, pII, p3, and p4 are all basically the same instruction set. the later versions add more MMX and SEE operations, and I don't believe gcc generates code that uses them. The different arch flags probably just change the instruction timing tables. -- Dan Nelson dnelson@allantgroup.com