From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH V5 2/6 net-next] netdevice.h: Add zero-copy flag in netdevice Date: Tue, 17 May 2011 09:21:11 +0300 Message-ID: <20110517062111.GD26989@redhat.com> References: <1305574128.3456.23.camel@localhost.localdomain> <1305574518.2885.25.camel@bwh-desktop> <1305574680.3456.33.camel@localhost.localdomain> <1305575253.2885.28.camel@bwh-desktop> <20110516211459.GE18148@redhat.com> <1305588738.3456.65.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Ben Hutchings , David Miller , Eric Dumazet , Avi Kivity , Arnd Bergmann , netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Shirley Ma Return-path: Received: from mx1.redhat.com ([209.132.183.28]:16501 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751841Ab1EQGVU (ORCPT ); Tue, 17 May 2011 02:21:20 -0400 Content-Disposition: inline In-Reply-To: <1305588738.3456.65.camel@localhost.localdomain> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, May 16, 2011 at 04:32:18PM -0700, Shirley Ma wrote: > Hello Michael, > > Looks like to use a new flag requires more time/work. > I am thinking > whether we can just use HIGHDMA flag to enable zero-copy in macvtap to > avoid the new flag for now since mavctap uses real NICs as lower device? > > Thanks > Shirley Problem is, in your patch there are a set of restrictions on what the device can do with the skb that we need to enforce somehow. Also, how do we know it's a 'real NIC' and not a software device? -- MST