From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Date: Tue, 24 Mar 2009 16:21:16 +0000 Subject: Re: Network Device Naming mechanism and policy Message-Id: <49C9087C.5070907@trash.net> List-Id: References: <20090324154617.GA16332@auslistsprd01.us.dell.com> In-Reply-To: <20090324154617.GA16332@auslistsprd01.us.dell.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Matt Domsch Cc: netdev@vger.kernel.org, linux-hotplug@vger.kernel.org, linux-kernel@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.