From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Mwhca-0007oo-Uf for qemu-devel@nongnu.org; Sat, 10 Oct 2009 15:28:52 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MwhcV-0007kr-9u for qemu-devel@nongnu.org; Sat, 10 Oct 2009 15:28:51 -0400 Received: from [199.232.76.173] (port=51213 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MwhcV-0007ko-33 for qemu-devel@nongnu.org; Sat, 10 Oct 2009 15:28:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:4386) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MwhcU-0006dW-KV for qemu-devel@nongnu.org; Sat, 10 Oct 2009 15:28:46 -0400 Date: Sat, 10 Oct 2009 21:26:35 +0200 From: "Michael S. Tsirkin" Subject: Re: [Qemu-devel] [PATCH 00/16] Add a -netdev option Message-ID: <20091010192635.GA14275@redhat.com> References: <1255028312-28180-1-git-send-email-markmc@redhat.com> <4ACF5612.7030400@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4ACF5612.7030400@codemonkey.ws> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Mark McLoughlin , qemu-devel@nongnu.org, Avi Kivity On Fri, Oct 09, 2009 at 10:26:10AM -0500, Anthony Liguori wrote: > Hi Mark, > > Mark McLoughlin wrote: >> Hi, >> Here's a series of patches which gets the ball rolling on adding >> a -netdev option. >> >> The idea is to de-emphasise the vlan support, and instead make >> a nic directly connected to a host backend the default and recommended >> configuration. We want this because it is only with this configuration >> that we feasibly add optimizations like GSO support or vhost-net. >> > > I think this series is a good first step. I've looked through the > patches and they all look pretty good. I plan on pushing after some > testing assuming noone objects in the interim. > > With respect to moving forward, I wanted to bring up a couple of topics. > > To eliminate VLANs, I think the reasonable approach is to implemented an > emulated hub. I'd suggest treating the hub like a device. Instantiate > it through qdev, support it via -device, etc. I think it would even be > reasonable to have it support a fixed number of ports. I doubt there > would be any compatibility issues emulating a 32-bit port hub, for > instance. > > The current syntax would become just a convenient short cut for the > -netdev syntax along with creating a hub device for each vlan that gets > instantiated. > > I think merging vhost_net support will depend on finishing out the > netdev work. More importantly, we need interrupt injection from kvm merged. We can have userspace poll vhost net and inject the interrupt, but I think this defeats the purpose of the in-kernel backend. > Logically, I think vhost_net is a netdev backend and we > extend the netdev API to support async submission of packets (basically > mirroring the virtio-net ABI). In the case of a virtio-net front-end to > a vhost_net backend, I think we special case that assuming we're running > kvm. > > Regards, > > Anthony Liguori