Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764297AbXHDJRH (ORCPT ); Sat, 4 Aug 2007 05:17:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751843AbXHDJQw (ORCPT ); Sat, 4 Aug 2007 05:16:52 -0400 Received: from einhorn.in-berlin.de ([192.109.42.8]:59294 "EHLO einhorn.in-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763965AbXHDJQs (ORCPT ); Sat, 4 Aug 2007 05:16:48 -0400 X-Envelope-From: stefanr@s5r6.in-berlin.de Message-ID: <46B443E5.2020404@s5r6.in-berlin.de> Date: Sat, 04 Aug 2007 11:16:21 +0200 From: Stefan Richter User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.4) Gecko/20070609 SeaMonkey/1.1.2 MIME-Version: 1.0 To: david@lang.hm CC: Ondrej Zajicek , Jan Engelhardt , Michael Tokarev , Herbert Rosmanith , linux-kernel@vger.kernel.org Subject: Re: renaming kernel devices [was: VIA EPIA EK: strange eth dev numbering] References: <200708021056.l72Au722008603@wildsau.enemy.org> <46B1BEB8.70104@msgid.tls.msk.ru> <20070802145152.GB19346@localhost.localdomain> <46B345E1.1010404@s5r6.in-berlin.de> In-Reply-To: X-Enigmail-Version: 0.94.1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3104 Lines: 67 david@lang.hm wrote: > On Fri, 3 Aug 2007, Stefan Richter wrote: >> There is a variety of possible naming schemes: >> >> - Naming by order of discovery. >> - Naming by vendor/model name strings. >> - Naming by universally unique identifier. >> - Naming by topology. >> - ... >> >> Only the simplest of these schemes (naming by order of discovery) (which is in most cases also the scheme that's the least useful to admins and users) >> is hardwired into the kernel portion of the Linux OS. The other naming >> schemes are (or can be) implemented in the userland portion of the >> Linux OS. ... > I understand the flexibility that this provides, unfortunantly (IMHO) > default udev rules (or at least what many distros are shipping by > default) changes from this simple naming scheme in a way that hides the > fact from the user. This means that many users will not even realize the > change in policy until the hardware changes and things don't act the way > they were expected to. In my case it was removing 3 quad cards from a > machine and finding that there was no eth0 on the box, instead there was > a eth12, this is fairly benign. what would have caused me significant > problems would have been having a card fail in a production box, have it > replaced and then found that the interfaces were now eth4-eth22 instead > of eth0-eth18. having the interfaces named differently on different > boxes with identical hardware based on the history of what has been > plugged into the boxes in the past is not what sysadmins expect. Yes, these rules by far don't fit everyone's needs. People who often use hotpluggable NICs are probably served best by MAC address based naming. Boxes with field replacable but otherwise fixed NICs apparently rather need a naming scheme based on PCI/PCIe topology. (This requires that the topology is exposed to userspace in comparable manner across boots and across kernel version updates.) So, an administrator should get to choose between different well documented naming schemes. Also, like Jan mentioned, confusion can already be minimized by renaming eth[0-9]+ -> net_[a-z]+ (for example, or nic[0-9]+ like Jan wrote) rather than eth[0-9]+ -> eth[0-9]+. That way it's clearer at all times whether the original names or names given by userspace are used. And there should be a log message when a device was renamed. Better yet, like Michal wrote: In case of device files for mass storage, there is no _renaming_. Instead, udev creates _aliases_ (symlinks), and it does so with a few different naming schemes at once so that admins or users immediately have a choice: $ ls /dev/disk/ by-id by-path by-uuid Any chance that there could be aliases to network interfaces? Aliases for device files are easy --- they live only in userspace. -- Stefan Richter -=====-=-=== =--- --=-- http://arcgraph.de/sr/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/