Date: Tue, 14 Feb 2006 09:25:24 -0500
To: Martin Mares <mj@ucw.cz>
Cc: Marcin Dalecki <dalecki.marcin@neostrada.pl>,
       Joerg Schilling <schilling@fokus.fraunhofer.de>,
       jerome.lacoste@gmail.com, peter.read@gmail.com, matthias.andree@gmx.de,
       linux-kernel@vger.kernel.org, jim@why.dont.jablowme.net,
       jengelh@linux01.gwdg.de, dhazelton@enter.net
Subject: Re: CD writing in future Linux (stirring up a hornets' nest)
Message-ID: <20060214142524.GC29940@csclub.uwaterloo.ca>
References: <20060208162828.GA17534@voodoo> <20060210114721.GB20093@merlin.emma.line.org> <43EC887B.nailISDGC9CP5@burner> <200602090757.13767.dhazelton@enter.net> <43EC8F22.nailISDL17DJF@burner> <5a2cf1f60602100738r465dd996m2ddc8ef18bf1b716@mail.gmail.com> <43F06220.nailKUS5D8SL2@burner> <mj+md-20060213.104344.18941.atrey@ucw.cz> <2D9D57EA-1197-4965-82ED-61DEAF73D9F9@neostrada.pl> <mj+md-20060214.091056.25971.atrey@ucw.cz>
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From: lsorense@csclub.uwaterloo.ca (Lennart Sorensen)
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On Tue, Feb 14, 2006 at 10:20:30AM +0100, Martin Mares wrote:
> That's unfortunately not true -- many USB devices don't have a usable
> serial number.
> 
> Also, if I have a single device of its kind, let's say a USB mouse,
> I really want to call it "The Mouse" and I don't want to reconfigure
> anything if I plug it to a different port or replace it with a slightly
> different mouse. All mice are considered equivalent by the user
> as there is no reason to distinguish between them.

Unless you are trying to setup two mice, two keyboards and two screens
on one machine at the same time.  Some people do that.  Then which mouse
is which is relevant.

> The same applies to CD burners -- as long as I have only one (which is
> still the most common situation), I shouldn't have to think about how
> to call it. Let it be just /dev/cdrw.

Many people have a cd writer and then add a dvd writer.  Not that
unusual really.

> When I get multiple such devices, things start getting interesting, but
> there is no single naming strategy which fits all uses. For example,
> if I have two USB ports into which I connect USB disks various people
> bring to me, it's convenient to call them "left" and "right", because
> the serial number doesn't mean anything to me if I haven't seen the
> device before. On the other hand, if I connect my own drives, it makes
> sense to call them by their serial numbers or something like that.
> 
> I think that it's clear from all this, that device naming is a matter
> of policy and that the best the OS can do is to give the users a way
> how to specify their policy, which is what udev does.

Well udev is starting to look useful.  It no longer causes lots of
breakage when I install it on my system. :)

Len Sorensen
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