Comment 21 for bug 341006

This has recently been discussed in #udev, and we found that it does not hurt that much to blacklist them. The kernel reliably sorts eth* enumeration by bus number, so as long as you only have cards from one vendor (or more precisely, drivers), the enumeration will be stable. Having cards from different vendors is very unlikely in VMs.

Marco submitted the blacklisting for kvm:

http://git.kernel.org/?p=linux/hotplug/udev.git;a=commitdiff;h=af29bf0966994bc233282148f519e12ea29e1c5a