From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756847Ab0DNUxO (ORCPT ); Wed, 14 Apr 2010 16:53:14 -0400 Received: from moutng.kundenserver.de ([212.227.126.171]:56138 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755749Ab0DNUxM (ORCPT ); Wed, 14 Apr 2010 16:53:12 -0400 From: Arnd Bergmann To: "Michael S. Tsirkin" Subject: Re: [RFC][PATCH v3 1/3] A device for zero-copy based on KVM virtio-net. Date: Wed, 14 Apr 2010 22:52:43 +0200 User-Agent: KMail/1.13.2 (Linux/2.6.31-19-generic; KDE/4.4.2; x86_64; ; ) Cc: xiaohui.xin@intel.com, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@elte.hu, davem@davemloft.net, jdike@linux.intel.com References: <1270805865-16901-1-git-send-email-xiaohui.xin@intel.com> <201004142239.50299.arnd@arndb.de> <20100414204003.GC11321@redhat.com> In-Reply-To: <20100414204003.GC11321@redhat.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201004142252.43931.arnd@arndb.de> X-Provags-ID: V01U2FsdGVkX1/UMe4LsK11bOJunXZdQTSvrmIbkHvVtmnvZoT yT2GBNuCeP/YPcay1manxcH2gYhGW3iRFfkNCWy/jDD2mRrwEj IhW0CH8TdlUb8J6h7o9ew== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 14 April 2010 22:40:03 Michael S. Tsirkin wrote: > On Wed, Apr 14, 2010 at 10:39:49PM +0200, Arnd Bergmann wrote: > > Well, if the guest not only wants to send data but also receive > > frames coming from other machines, they need to get from the kernel > > into qemu, and the only way I can see for doing that is to read > > from this device if there is no vhost support around on the new > > machine. > > > > Maybe we're talking about different things here. > > mpassthrough is currently useless without vhost. > If the new machine has no vhost, it can't use mpassthrough :) Ok. Is that a planned feature though? vhost is currently limited to guests with a virtio-net driver and even if you extend it to other guest emulations, it will probably always be a subset of the qemu supported drivers, but it may be useful to support zero-copy on other drivers as well. Arnd