From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261822AbUBYXjL (ORCPT ); Wed, 25 Feb 2004 18:39:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261656AbUBYXgN (ORCPT ); Wed, 25 Feb 2004 18:36:13 -0500 Received: from kinesis.swishmail.com ([209.10.110.86]:42252 "EHLO kinesis.swishmail.com") by vger.kernel.org with ESMTP id S261669AbUBYXev (ORCPT ); Wed, 25 Feb 2004 18:34:51 -0500 Message-ID: <403D3379.60604@techsource.com> Date: Wed, 25 Feb 2004 18:44:57 -0500 From: Timothy Miller MIME-Version: 1.0 To: "Nakajima, Jun" CC: "H. Peter Anvin" , linux-kernel@vger.kernel.org Subject: Re: Intel vs AMD x86-64 References: <7F740D512C7C1046AB53446D37200173EA27D6@scsmsx402.sc.intel.com> In-Reply-To: <7F740D512C7C1046AB53446D37200173EA27D6@scsmsx402.sc.intel.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 Nakajima, Jun wrote: > For near branches (CALL, RET, JCC, JCXZ, JMP, etc.), the operand size is > forced to 64 bits on both processors in 64-bit mode, basically meaning > RIP is updated. > > Compilers would typically use a JMP short for "intraprocedural jumps", > which requires just an 8-bit displacement relative to RIP. I see. It's too bad you can't have a 16-bit displacement. Ummm... so if 66H were used with a near branch, would that affect the size of the immediate operand which gets added to RIP, or would that affect the the portion of IP/EIP/RIP affected? If it's the latter, that's pretty silly.