From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: QEMU PIC indirection patch for in-kernel APIC work Date: Mon, 09 Apr 2007 12:50:18 +1000 Message-ID: <1176087018.11664.65.camel@localhost.localdomain> References: <4613B438.60107@codemonkey.ws> <4613B89F.8090806@qumranet.com> <4613BC6B.1070708@codemonkey.ws> <4613BF07.50606@qumranet.com> <4613C993.9020405@codemonkey.ws> <4613CC01.1090500@qumranet.com> <4613CDB2.4000903@codemonkey.ws> <4613D001.3040606@qumranet.com> <20070404200112.GA6070@elte.hu> <4614098F.2030307@us.ibm.com> <20070404212103.GA19026@elte.hu> <1175728768.12230.593.camel@localhost.localdomain> <4614A294.3000607@qumranet.com> <1175821357.12230.642.camel@localhost.localdomain> <46187F4E.1080807@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, netdev To: Avi Kivity Return-path: In-Reply-To: <46187F4E.1080807-atKUWr5tajBWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: netdev.vger.kernel.org On Sun, 2007-04-08 at 08:36 +0300, Avi Kivity wrote: > Rusty Russell wrote: > > Hi Avi, > > > > I don't think you've thought about this very hard. The receive copy is > > completely independent with whether the packet is going to the guest via > > a kernel driver or via userspace, so not relevant. > > > > A packet received in the kernel cannot be made available to userspace in > a safe manner without a copy, as it will not be aligned with page > boundaries, so userspace cannot examine the packet until after one copy > has occured. Hi Avi! I'm a little puzzled by your response. Hmm... lguest's userspace network frontend does exactly as many copies as Ingo's in-host-kernel code. One from the Guest, one to the Guest. Does that clarify? Rusty. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV