Subject: Re: marching unit numbers
To: Chris G. Demetriou <>
From: Bill Studenmund <>
List: tech-kern
Date: 12/30/1999 15:42:44
On 30 Dec 1999, Chris G. Demetriou wrote:

> Curt Sampson <> writes:
> > E.g., I have two ethernet cards, foo3 and foo4. When I yank them
> > out and insert them in reverse order, they still get their original
> > device numbers back (because the driver recognises the MAC addresses).
> > When I yank one out and insert a brand new one, it gets foo5.
> > 
> > I don't know if this is really worth the effort, however.
> I think in a sane world that does dynamic configuration, if you're
> depending on unit numbers being hard-ish-coded and you've not (somehow)
> wired them down in your config file, you'll lose.

If I may take the liberty, I think Curt was suggesting something a little
different. Say the system has recognized two hot swapped cards as foo3 and
foo4 (say ethernet interfaces). If we eject them and reinsert them, it'd
be nice for them to come back as foo3 and foo4 even if we insert them in
the opposite order.

This is a little different in that we don't require that what was foo4
last boot will be foo4 this boot nor foo4 next boot. Just that if
something becomes foo4 once we're booted, it's the only thing which will
become foo4 until reboot.

I'm not sure if it's what we want to do, but I think that was the idea.

Take care,