From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261191AbUB0DQA (ORCPT ); Thu, 26 Feb 2004 22:16:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261559AbUB0DQA (ORCPT ); Thu, 26 Feb 2004 22:16:00 -0500 Received: from mail.tmr.com ([216.238.38.203]:18821 "EHLO gaimboi.tmr.com") by vger.kernel.org with ESMTP id S261191AbUB0DP6 (ORCPT ); Thu, 26 Feb 2004 22:15:58 -0500 Message-ID: <403EB692.60309@tmr.com> Date: Thu, 26 Feb 2004 22:16:34 -0500 From: Bill Davidsen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6b) Gecko/20031208 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Timothy Miller CC: "Nakajima, Jun" , "H. Peter Anvin" , linux-kernel@vger.kernel.org Subject: Re: Intel vs AMD x86-64 References: <7F740D512C7C1046AB53446D37200173EA288C@scsmsx402.sc.intel.com> <403E1914.5060209@techsource.com> In-Reply-To: <403E1914.5060209@techsource.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Timothy Miller wrote: > > > Nakajima, Jun wrote: > >> Yes, that's the very reason I said "useless for compilers." The way >> IP/RIP is updated is different (and implementation specific) on those >> processors if 66H is used with a near branch. For example, RIP may be >> zero-extended to 64 bits (from IP), as you observed before. >> > > This is obviously an extremely minor nit-pick, because we're talking > about one instruction here with an interpretation that is far from > obvious, but given that there are now only two architectures which > support x86-64, did Intel choose to do it differently from AMD because > it was poorly defined, or because it wasn't important enough to want to > impact the efficiency of the design? How about because they messed up trying to clone the instruction set? Never attribute to malice what can be explained by stupidity. <-(quote) > > There are people who would go way out of their way to get a 5% > improvement in performance or decrease in size. If using 66H with near > branches could in some way do that, they would really really want to use > it. This is why I'm curious. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979