Date: Mon, 15 Oct 2007 19:54:22 -0700 (PDT)
From: david@lang.hm
To: Greg KH <greg@kroah.com>
cc: Rob Landley <rob@landley.net>, Julian Calaby <julian.calaby@gmail.com>,
       Theodore Tso <tytso@mit.edu>,
       James Bottomley <James.Bottomley@steeleye.com>,
       Matthew Wilcox <matthew@wil.cx>, linux-kernel@vger.kernel.org,
       linux-scsi@vger.kernel.org, Jens Axboe <axboe@suse.de>,
       Suparna Bhattacharya <suparna@in.ibm.com>,
       Nick Piggin <piggin@cyberone.com.au>
Subject: Re: What still uses the block layer?
In-Reply-To: <20071015173357.GB5738@kroah.com>
Message-ID: <Pine.LNX.4.64.0710151952250.3949@asgard.lang.hm>
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 <646765f40710150206j75af4c4dwac4f4565451b64b1@mail.gmail.com>
 <200710150508.37332.rob@landley.net> <20071015173357.GB5738@kroah.com>
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On Mon, 15 Oct 2007, Greg KH wrote:

> On Mon, Oct 15, 2007 at 05:08:36AM -0500, Rob Landley wrote:
>> On Monday 15 October 2007 4:06:20 am Julian Calaby wrote:
>>> On 10/15/07, Rob Landley <rob@landley.net> wrote:
>>>> I note that the eth0 and eth1 names are dynamically assigned on a first
>>>> come first serve basis (like scsi).  This never causes me a problem
>>>> because the driver loading order is constant, and once you figure out
>>>> that eth0 is gigabit and eth1 is the 80211g it _stays_ that way across
>>>> reboots, reliably. Yeah, it's a heuristic.  Hands up everybody relying on
>>>> such a heuristic in the real world.
>>>
>>> Umm, not quite, from my experiences with pre-production wireless
>>> drivers, (another story, another time) fancy stuff is being done in
>>> udev to make sure that your gigabit card is always assigned to eth0.
>>
>> I remember building a 2.4 kernel, statically linking in all the drivers, and
>> getting the ethernet devices showing up in a reliable order for years.  Where
>> does the need for fancy stuff come in?
>
> Because PCI devices reorder their bus numbers all the time.  And we have
> ethernet devices hanging off of USB connections now (yes, even built-in
> to the machine), and we have network connections on other hot-pluggable
> busses (remember, PCI is hot pluggable.)

do PCI devices reorder their bus numbers spontaniously, or only if you 
change the hardware?

> So, the distros need to name network devices in a persistant way, that
> is why the distros now do this.  If you don't like the distro doing it,
> complain to them, it's not a kernel issue :)

I have, at least the response was to tell me how to kill this 'feature' 
even if they won't change it.

David Lang

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