From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: dhclient, checksum and tap Date: Fri, 25 Jun 2010 11:21:52 -0700 (PDT) Message-ID: <20100625.112152.241921019.davem@davemloft.net> References: <20100625151008.GA17911@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: herbert.xu@redhat.com, netdev@vger.kernel.org To: mst@redhat.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:34106 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753016Ab0FYSVj (ORCPT ); Fri, 25 Jun 2010 14:21:39 -0400 In-Reply-To: <20100625151008.GA17911@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: From: "Michael S. Tsirkin" Date: Fri, 25 Jun 2010 18:10:08 +0300 > I've been looking at the issue of checksum on > dhcp packets: to recap, 8dc4194474159660d7f37c495e3fc3f10d0db8cc > added a way for af_packet sockets to get the packet status. > Unfortunately not all dhcp clients caught up with > this development, so they are still broken > when both server and client run on the same host, > e.g. with bridge+tap. > > And of course virtualization adds another way to run > old dhcp clients, so userspace virtio net in qemu has > a hack to detect DHCP and fill in the checksum. > I guess we could add this in vhost, as well. > > However, one wonders whether the tap driver is a better place > for this work-around, that would help all users. > Any objections against putting such code in tap? We added the af_packet status as the migration path to deal with this issue in the cleanest manner possible. Putting a new hack into the TAP driver works contrary to that goal.