On Tue, Dec 04, 2007 at 05:49:10PM +0000, Daniel P. Berrange wrote: > On Tue, Dec 04, 2007 at 05:40:44PM +0000, Richard W.M. Jones wrote: > > Daniel P. Berrange wrote: > > >For the QEMU / KVM driver, if the user doesn't specify an explicit name for > > >the TAP device associated with a virtual NIC, we auto-generate one with a > > >name vnetXXX. You can see this if you dump XML for a running QEMU guest. > > >Unfortunately if you dump XML, make a change and then feed it back in with > > >the define XML API, you have now persisted this auto-generated VIF name. > > > > > >Do this for several domains at varying times and you'll eventually get > > >2 domains which have persisted the same auto-generated vnetXXX device > > >name. You can now not start both of these VMs at once. > > > > > >The fix for this is simple - simply strip any TAP device name starting with > > >the string 'vnet' when defining a new VM. It will thus get assigned a new > > >automatically generate name which doesn't clash. The patch also strips out > > >hardcoded vnetXXX names when starting a VM to proactively deal with any > > >existing VMs whose config has been broken in this way. > > > > Hang about though, don't we sometimes want to explicitly set the name of > > some interfaces to vnetXXX? > > No, if you want to manually set interface names, you have to use something > other than a 'vnet' prefix. 'vnet' is the prefix for auto-generated names > in same way as 'vif' is the prefix for Xen auto-generated names. okay, makes sense then, Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard@xxxxxxxxxx | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/ -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list