From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262108AbTI0EeN (ORCPT ); Sat, 27 Sep 2003 00:34:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262109AbTI0EeN (ORCPT ); Sat, 27 Sep 2003 00:34:13 -0400 Received: from palrel12.hp.com ([156.153.255.237]:54682 "EHLO palrel12.hp.com") by vger.kernel.org with ESMTP id S262108AbTI0EeM (ORCPT ); Sat, 27 Sep 2003 00:34:12 -0400 From: David Mosberger MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16245.4929.723220.900314@napali.hpl.hp.com> Date: Fri, 26 Sep 2003 21:34:09 -0700 To: Andi Kleen Cc: "David S. Miller" , davidm@napali.hpl.hp.com, linux-kernel@vger.kernel.org Subject: Re: NS83820 2.6.0-test5 driver seems unstable on IA64 In-Reply-To: References: X-Mailer: VM 7.07 under Emacs 21.2.1 Reply-To: davidm@hpl.hp.com X-URL: http://www.hpl.hp.com/personal/David_Mosberger/ Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >>>>> On Sat, 27 Sep 2003 06:26:40 +0200, Andi Kleen said: Andi> You handle misalignment->misalignment copies with zero or Andi> small cost - when both source and destination have the same Andi> misalignment. I guess you do that by just aligning the pointer Andi> at the beginning of the function. That works as long as both Andi> source and destination have the same misalignment. Andi> But that is not what happens here. The copy is a Andi> misaligned->aligned copy and that cannot be handled at zero Andi> cost (unless you have zero misalignment penalty in Andi> load/store). Either the load or the store in the copy loop Andi> will be always misaligned, no matter what tricks you play. You Andi> cannot avoid this by aligning the pointers. Geez, Andi, get a clue. You've been working with x86 for too long. You really can't imagine that you could combine two source words into a single destination word? Look ma, no unaligned accesses... --david