From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: Network Device Naming mechanism and policy Date: Tue, 24 Mar 2009 17:21:16 +0100 Message-ID: <49C9087C.5070907@trash.net> References: <20090324154617.GA16332@auslistsprd01.us.dell.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-hotplug@vger.kernel.org, linux-kernel@vger.kernel.org To: Matt Domsch Return-path: In-Reply-To: <20090324154617.GA16332@auslistsprd01.us.dell.com> Sender: linux-hotplug-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Matt Domsch wrote: > 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. 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.