From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Skorodumov Subject: Re: [PATCH] [NetKVM] Fix checksum verification for pkts with csum==0xffff Date: Thu, 14 Mar 2013 12:52:16 +0000 (UTC) Message-ID: References: <1363265152-11080-1-git-send-email-sdmitry@parallels.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from plane.gmane.org ([80.91.229.3]:50552 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750989Ab3CNMym (ORCPT ); Thu, 14 Mar 2013 08:54:42 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1UG7gV-00019G-I9 for kvm@vger.kernel.org; Thu, 14 Mar 2013 13:55:03 +0100 Received: from swsoft-msk-nat.sw.ru ([195.214.232.10]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 14 Mar 2013 13:55:03 +0100 Received: from sdmitry by swsoft-msk-nat.sw.ru with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 14 Mar 2013 13:55:03 +0100 Sender: kvm-owner@vger.kernel.org List-ID: > Dmitry Skorodumov parallels.com> writes: > > Windows-host with disabled TX-checksum offloading may send > packets with tcp->checksum=0xffff. Most likely it is caused > by by Windows algorithm for computing incremental checksum > - see RFC 1624. Forgot to mention that packets with checksum 0xffff appears almost 100% if run from windows-host to kvm-guest netperf -H -t TCP_RR Dmitry