Two NICs - swapped initialization

[Kenneth]

--- Kevin Brown <kevin_brown at qwest.net> wrote:

> > Hoping someone knows this one, to save me what would probably turn into a
> > couple of days of research to satisfy my curiosity :)
> > 
> > I have been running Gentoo for a while, and this machine is my router and
> > firewall. It has two ethernet controllers in it.  When I first installed,
> it
> > called the controller I wanted to be eth0, eth1 and vice versa (I know it
> > doesn't really matter, but it's a personal idiosyncracy).  I placed the
> names
> > for the modules in the /etc/modules.autoload.d/kernel-2.6 file, with the
> one
> > I wanted to be eth0 first, and that got them in my preferred order so I
> > assumed that the first loaded module would be eth0.
> > 
> > Well after an update the other day, the two swapped places and I wasn't
> able
> > to get them back, so finally just left them.  It wasn't all bad, I
> discovered
> > a bug in my firewall setup script when it failed, but I'm curious what
> > decides which controller is which, and how it could change on it's own.
> 
> The order of the naming of the devices is based on the order they are 
> discovered on the PCI bus.  It is possible that an update to the kernel 
> resulted in a reversal of the discovery order and so reverse the names. 
>   Back when I had a small linux router (P166 box) I had put entries in 
> modprobe.conf or conf.modprobe (been so long) that dictated the naming 
> of each device based on the MAC address to correct for this issue. 
> Another way might be to specify which NIC is which in the config files.
> 
> This is a RH specific link, but might help you figure out how to do 
> things in Gentoo.
> http://linux.dell.com/files/whitepapers/nic-enum-whitepaper-v2.pdf

Thanks for the link.  I guess I knew it had to be whatever the kernel scanned
first, I guess I was hoping there was a simple way to force it.  There was a
kernel update, and that was probably when the switch occurred.  I didn't use
the new one right away so I'm not sure.



 
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