From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57203) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VOlPR-0003NK-NW for qemu-devel@nongnu.org; Wed, 25 Sep 2013 05:29:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VOlPL-000269-Ky for qemu-devel@nongnu.org; Wed, 25 Sep 2013 05:29:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:29803) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VOlPK-00025y-Vj for qemu-devel@nongnu.org; Wed, 25 Sep 2013 05:29:19 -0400 Date: Wed, 25 Sep 2013 12:31:27 +0300 From: "Michael S. Tsirkin" Message-ID: <20130925093127.GB6320@redhat.com> References: <20130922085920.GB32658@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [RFC] sync NIC's MAC maintained in NICConf as soon as emualted NIC's MAC changed in guest List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Zhanghaoyu (A)" Cc: "chenliang (T)" , "Huangweidong (C)" , Gleb Natapov , "paolo.bonzini@gmail.com" , Jason Wang , Luonengjun , qemu-devel , Xiahai On Wed, Sep 25, 2013 at 09:02:54AM +0000, Zhanghaoyu (A) wrote: > >> Hi, all > >> > >> Do live migration if emulated NIC's MAC has been changed, RARP with > >> wrong MAC address will broadcast via qemu_announce_self in destination, so, long time network disconnection probably happen. > > > >Good catch. > > > >> I want to do below works to resolve this problem, 1. change NICConf's > >> MAC as soon as emulated NIC's MAC changed in guest > > > >This will make it impossible to revert it correctly on reset, won't it? > > > You are right. > virsh reboot , or virsh reset , or reboot VM from guest, will revert emulated NIC's MAC to original one maintained in NICConf. > During the reboot/reset flow in qemu, emulated NIC's reset handler will sync the MAC address in NICConf to the MAC address in emulated NIC structure, > e.g., virtio_net_reset sync the MAC address in NICConf to VirtIONet'mac. > > BTW, in native scenario, reboot will revert the changed MAC to original one, too. > > >> 2. sync NIC's (more precisely, queue) MAC to corresponding NICConf in > >> NIC's migration load handler > >> > >> Any better ideas? > >> > >> Thanks, > >> Zhang Haoyu > > > >I think announce needs to poke at the current MAC instead of the default one in NICConf. > >We can make it respect link down state while we are at it. > > > NICConf structures are incorporated in different emulated NIC's structure, e.g., VirtIONet, E1000State_st, RTL8139State, etc., > since so many kinds of emulated NICs, they are described by different structures, how to find all NICs' current MAC? > > Maybe we can introduce a pointer member 'current_mac' to NICConf structure, which points to the current MAC, > then we can find all current MACs from NICConf.current_mac. I wouldn't make it a pointer, just a buffer with the mac, copy it there. Maybe call it "softmac" that's what it is really. > Can we broadcast the RARP with current MAC in NIC's migration load handler respectively? > > Thanks, > Zhang Haoyu It's not so simple, you need to retry several times. > >Happily recent linux guests aren't affected since they do announcements from guest. > > > >-- > >MST