Daniel P. Berrange wrote: > On Wed, Nov 19, 2008 at 11:20:08PM -0700, Jim Fehlig wrote: > >> Hi All, >> >> I wanted to get folks thoughts on relaxing the requirement for bridge >> source device in network interface of domain XML, e.g. allowing >> >> <interface type="bridge"> >> <mac address="aa:bb:cc:cc:ee:ff"/> >> </interface> >> >> Currently, virDomainNetDefParseXML() in src/domain_conf.c will fail such >> configuration. Since this is common code between backends I'm not sure >> how allowing this config will affect the various virtualizers. >> >> Xen's vif-bridge script will try to find a bridge if one is not >> specified, which perhaps is dubious behavior, but nonetheless convenient >> in migration scenarios where the target host may have a different bridge >> name (br1 vs br0 for example). IIRC, qemu's qemu-ifup script is not as >> forgiving in the absence of a bridge name. >> > > I don't particularly like this idea. While letting it automatically > pick the bridge devices may happen to work in some cases, it'll > quietly go wrong horribly in other scenarios. Xen's vif-bridge > has caused real bugs through this behaviour even on a single machine. > eg, its happily automatically picking br0 for months, then someone > adds a new completely unrelated bridge to the machin, say br4, and > the next reboot vif-bridge suddenly decides it prefers br4 for your > guest. Yep, have seen this behavior when leaving source unspecified. > I think it is not unreasonable in the case of migraiton to > require that the bridge names are configured the same on source and > destination machine, and explicitly including bridge names will let > apps using libvirt query the source & destination host before doing > migraiton and verify that br0 on the source is configured to use the > same network as br0 on the destination. > Agreed. Thanks for the feedback Daniel. Jim -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list