From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756736Ab0I1PSo (ORCPT ); Tue, 28 Sep 2010 11:18:44 -0400 Received: from moutng.kundenserver.de ([212.227.126.186]:58648 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756666Ab0I1PSl (ORCPT ); Tue, 28 Sep 2010 11:18:41 -0400 From: Arnd Bergmann To: "Michael S. Tsirkin" Subject: Re: [PATCH v11 13/17] Add mp(mediate passthru) device. Date: Tue, 28 Sep 2010 17:18:15 +0200 User-Agent: KMail/1.12.2 (Linux/2.6.35-16-generic; KDE/4.3.2; x86_64; ; ) Cc: Ben Hutchings , xiaohui.xin@intel.com, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@elte.hu, davem@davemloft.net, herbert@gondor.hengli.com.au, jdike@linux.intel.com, Sridhar Samudrala References: <1285388855-27410-1-git-send-email-xiaohui.xin@intel.com> <201009281639.59417.arnd@arndb.de> <20100928144311.GB15294@redhat.com> In-Reply-To: <20100928144311.GB15294@redhat.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201009281718.15813.arnd@arndb.de> X-Provags-ID: V02:K0:vqSDyROpukhnEbIYwlawrY+wEt5xYskq5VTtGOPPiP0 NlN4etuOtsTo3wRwJjKDRSUR7nOdiuzE3X6YKh9VwYNDfIujdl yxY/XwxRnZt4ehOspiZcLAgzhVayMHrPd25Uw2lr+NbcZYjXyh x+JPIaag2AzgJKALGR7azNi10eKs6hvq4K/rxC17+Q9hCPiR7Q Yh4SrCJFgZstDzJP8LMPA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 28 September 2010, Michael S. Tsirkin wrote: > On Tue, Sep 28, 2010 at 04:39:59PM +0200, Arnd Bergmann wrote: > > Can you be more specific what the problem is? Do you think > > it breaks when a guest sends VLAN tagged frames or when macvtap > > is connected to a VLAN interface that adds another tag (or > > only the combination)? > > I expect the protocol value to be wrong when guest sends vlan tagged > frames as 802.1q frames have a different format. Ok, I see. Would that be fixed by using eth_type_trans()? I don't see any code in there that tries to deal with the VLAN tag, so do we have the same problem in the tun/tap driver? Also, I wonder how we handle the case where both the guest and the host do VLAN tagging. Does the host transparently override the guest tag, or does it add a nested tag? More importantly, what should it do? Arnd