>> >> 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. > Could you make a statement for 'retry several times' ? Is it the process of retrying several times to sending RARP in qemu_announce_self_once?
'broadcast the RARP with current MAC in NIC's migration load handler respectively' is distributing the job of what qemu_announce_self does to every NIC's migration load handler, e.g., in virtio NIC's migration load handler virtio_net_load, we can create a timer to retry several times to send ARAP with current MAC for this NIC, just as same as qemu_announce_self does. >> >Happily recent linux guests aren't affected since they do announcements >> >from guest. >> > >> >-- >> >MST