From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Date: Fri, 30 Oct 2009 16:34:06 +0000 Subject: Re: [PATCH] udev: create empty regular files to represent net Message-Id: <20091030093406.05bb7e20@nehalam> List-Id: References: <20091016214024.GA10091@ldl.fc.hp.com> <20091022063619.GB6321@ldl.fc.hp.com> <20091027205551.GA31963@auslistsprd01.us.dell.com> <4AEA997D.7070205@suse.de> <4AEB12CC.1070300@kadzban.is-a-geek.net> In-Reply-To: <4AEB12CC.1070300@kadzban.is-a-geek.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Bryan Kadzban Cc: Hannes Reinecke , Kay Sievers , Matt Domsch , dann frazier , linux-hotplug@vger.kernel.org, Narendra_K@dell.com, netdev@vger.kernel.org, Jordan_Hargrave@dell.com, Charles_Rose@dell.com, Ben Hutchings On Fri, 30 Oct 2009 09:22:36 -0700 Bryan Kadzban wrote: > Hannes Reinecke wrote: > > And to throw in some bit of useless information; > > Stirring the pot a bit myself with this message... > > > The one reason I didn't to this was that a network interface is _not_ > > a file, but rather an abstract type which is known only internally in > > the kernel (ie the one exemption from the 'everything is a file' UNIX > > rule). > > Why? Why not make it a file? I've heard rumors of other Unix-like > systems that do exactly that, FWIW. > > (Yes, I'm joking. Well, maybe half-joking... It'd be nice, but I don't > expect it to happen.) > > > When I were to design this, I would be implementing network interface > > _aliases_, so that a network interface could be accessed either by > > name or by alias. This mechanism can then be managed by udev, much > > like we (ie SUSE) is using it nowadays to assign the network > > interface numbers. > > The problem with that, if I understand what you're suggesting, is the > value of IFNAMSIZ, and the fact that it can't be made any bigger. All > your aliases have to be IFNAMSIZ characters or less. And that's too > short to be able to embed the same level of information as we get for > e.g. disks. It's *barely* long enough to fit "mac-" plus 12 hex digits > (for the MAC address), but is completely incapable of holding a USB bus > path, for instance. > > (Not that you'd want to use path persistence for USB devices. But it is > possible that you'd want it for some other setup, at which point it > becomes impossible to use the same rules for USB.) Not a big fan of multiple names, it is the wrong solution to the human question of "what is eth0 really?". Router o/s use description field for that kind of information. I added ifalias to provide place to put user visible description information. It is in latest kernels via sysfs and iproute utilities. Also plan to add support for it in net-snmp. --