From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 29 Sep 2002 02:55:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 29 Sep 2002 02:54:59 -0400 Received: from web14602.mail.yahoo.com ([216.136.224.82]:57352 "HELO web14602.mail.yahoo.com") by vger.kernel.org with SMTP id ; Sun, 29 Sep 2002 02:54:58 -0400 Message-ID: <20020929070021.7735.qmail@web14602.mail.yahoo.com> Date: Sun, 29 Sep 2002 00:00:21 -0700 (PDT) From: Arvind Gopalan Subject: Re: 4 byte mem alignment To: linux-kernel@vger.kernel.org Cc: "David S. Miller" In-Reply-To: <20020928.232326.43409659.davem@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Thanks Dave, for confirming my doubt. I have some user level code that uses raw sockets on linux. The code ran on several dual PIII x86 machines without any issues. But since the time we started running (the same code with no changes) on the dual x86 xeons, i have seen some wierd corruption issues with the packets. This kernel already has the patch for the xeon TLB flush bug. On some of the eth packets that I dumped, i found that 8 bytes of data being "copied and inserted"!. As in after a certain offset into the packet, there would be a sequence of 8 bytes that would be an exact copy of the 8 bytes that appeared just before. All other following bytes were literally shifted down by 8. How can i proceed to debug this sort of a problem. if its a xeon specific issue, how can i isolate it?. Thanks -Arvind --- "David S. Miller" wrote: > From: Arvind Gopalan > Date: Sat, 28 Sep 2002 23:26:46 -0700 (PDT) > > how strong the requirements are for > copy_to_user(). > does it fault to byte-by-byte mode gracefully > when > given a non-4byte aligned buffer?. > > The x86 processor handles unaligned memory accesses > in hw. > > On any platform, copy_to_user() must handle any user > and kernel buffer > alignment. __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com