Re: What determines ethernet order?

B. James Phillippe (bryan@terran.org)
Wed, 8 Jul 1998 11:41:57 -0700 (PDT)


On Wed, 8 Jul 1998, Brian Schau wrote:

> > Hello,
> >
> > I'm struggling with a few PCI problems I've run into lately on a
> > couple motherboards. My understanding has been that Linux(-2.0) uses the
> > PCI BIOS to determine what PCI cards are present, and the order of cards
> > present is by physical slot order. Then, when a PCI ethernet driver wants
> > to initialize multiple PCI NIC's, they are initialized in that same
> > physical slot order (since the driver just walks down the list from start
> > to end). However, I have recently witnessed the slot order change out from
> > under me on a few of the motherboards I'm testing, and that seems to knock
> > a big hole in my understanding. :) Can anyone offer me an explanation of
> > how PCI ethernet drivers order the NIC's (logically; eth0, eth1, so forth)?
> > I would be very appreciative!
>
> AFAIK it's the MAC-addess of the nic's which decides order. Lower macs
> first. You might want to have a look at 'Multiple-Ethernet-Mini-HOWTO'
> (... or something like that ... - it's on www.linuxresources.com!)

I believe that's true only for ISA/EISA cards, but not for PCI. PCI cards
are detected independant of the MAC. Anyone able to confirm? If indeed
this is the case, what is the methodology used to determine what order
PCI cards are detected in? I'm on my way through a tour of the kernel
source now to see if I can answer it for myself, but some words of wisdom
from a guru would be most appreciated!

thanks,
-bp

--
B. James Phillippe <bryan@terran.org>
Linux Software Engineer, WGT Inc.
http://earth.terran.org/~bryan

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