On Tue, Mar 24, 2009 at 17:21, Patrick McHardy [off-list ref] wrote:

Matt Domsch wrote:

quoted

2) udev may have rules to change the device names.  This is most often
  seen in the '70-persistent-net.rules' file.  Here we have
  additional challenges:

...

  c) udev may not always be able to change a device's name.  If udev
     uses the kernel assignment namespace (ethN), then a rename of
     eth0->eth1 may require renaming eth1->eth0 (or something else).
     Udev operates on a single device instance at a time, it becomes
     difficult to switch names around for multiple devices, within
     the single namespace.

I would classify this as a bug, especially the fact that udev doesn't
undo a failed rename, so you end up with ethX_rename. Virtual devices
using the same MAC address trigger this reliably unless you add
exceptions to the udev rules.

This is handled in most cases. Virtual interfaces claiming a
configured name and created before the "hardware" interface are not
handled, that's right, but pretty uncommon.

You state that it only operates on one device at a time. If that is
correct, I'm not sure why the _rename suffix is used at all instead
of simply trying to assign the final name, which would avoid this
problem.

How? The kernel assignes the names and the configured names may
conflict. So you possibly can not rename a device to the target name
when it's name is already taken. I don't see how to avoid this.

Thanks,
Kay