From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:53484) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ucwzk-0002lV-6Z for qemu-devel@nongnu.org; Thu, 16 May 2013 08:09:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ucwzb-0003BW-39 for qemu-devel@nongnu.org; Thu, 16 May 2013 08:09:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48955) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ucwza-0003BE-QU for qemu-devel@nongnu.org; Thu, 16 May 2013 08:09:07 -0400 Date: Thu, 16 May 2013 15:09:06 +0300 From: "Michael S. Tsirkin" Message-ID: <20130516120906.GC31841@redhat.com> References: <5119E9DC.3000505@dlhnet.de> <1368541284.15129.317.camel@eboracum.office.bytemark.co.uk> <519249F6.3000900@dlhnet.de> <1368542949.15129.354.camel@eboracum.office.bytemark.co.uk> <1368615603.15129.1471.camel@eboracum.office.bytemark.co.uk> <20130516062405.GA26548@redhat.com> <20130516062743.GB26548@redhat.com> <1368692455.15129.1475.camel@eboracum.office.bytemark.co.uk> <20130516084021.GA28125@redhat.com> <1368703672.15129.1501.camel@eboracum.office.bytemark.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1368703672.15129.1501.camel@eboracum.office.bytemark.co.uk> Subject: Re: [Qemu-devel] tap devices not receiving packets from a bridge List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Nicholas Thomas Cc: Stefan Hajnoczi , Peter Lieven , qemu-devel@nongnu.org, netdev@vger.kernel.org On Thu, May 16, 2013 at 12:27:52PM +0100, Nicholas Thomas wrote: > On Thu, 2013-05-16 at 11:40 +0300, Michael S. Tsirkin wrote: > > On Thu, May 16, 2013 at 09:20:55AM +0100, Nicholas Thomas wrote: > > > Hi, > > > > > > On Thu, 2013-05-16 at 09:27 +0300, Michael S. Tsirkin wrote: > > > > On Thu, May 16, 2013 at 09:24:05AM +0300, Michael S. Tsirkin wrote: > > > > > Is this with or without vhost-net in host? > > > > > > > > never mind, I see it's without. > > > > Try to enable vhost-net (you'll have to switch to -netdev syntax > > > > for that to work) and see if this help. > > > > If it does it's likely a qemu bug if not probably a guest bug. > > > > > > Switching to -netdev is non-trivial for me, unfortunately. > > > > Interesting. Why is that? > > Our setup is bond0 <-> vlanX <-> bridgeX <-> [ tap devices ] and we do > all that outside of qemu at the moment, specifying -net tap,ifname=... - > we also run some processes on the TAP interface and insert a bunch of > ebtables rules between creating it and starting qemu. Duplicating that > with -net bridge seemed close to impossible, and -netdev tap was > throwing EBUSY from /dev/net/tun. I guess our external magic should be > using ,fd= instead. I'm not sure what's wrong with -netdev tap. You don't have to use fd=, you can specify ifname= with netdev as well. Here's what I use: -net nic,model=virtio,netdev=foo -netdev tap,id=foo,ifname=msttap0,script=/home/mst/ifup,downscript=no,vhost=on the netdev/id pair above is almost the same as vlan=20 in your example, except there's always exactly one frontend and one backend in the netdev case, vlans let you connect more than 2 devices. > > > Anyway, it's > > > definitely a qemu bug - it happens on kernels 3.2 and 3.9 with 1.4.1, > > > but doesn't happen with qemu 0.15.0 or 1.5.0rc1. > > > > > > I'll have a dig through git to see if I can identify the patch that > > > resolves it. It feels-like qemu sometimes stops reading from the tap > > > file descriptor between ipxe exiting and the linux kernel bringing up > > > the network interface, and never recovers from that. > > > > > > /Nick > > > > You can try to bisect, yes. > > Work have decided to accept 1.5.0 when it arrives instead, so I'm afraid > I won't be working on this after all. > > /Nick > >