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 <domain>, or virsh reset <domain>, 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