probe ordering of interfaces

[Barry Bouwsma]

[please drop me from replies and keep it on the list]

A stupid question, which probably has been covered in the archives
somewhere where I'm not looking.

What determines the probe/attach ordering during boot?

Specifically, I want to swap attach order of two devices
that end up as umass, and wiring the device will not give
the desired result.

More specifically, I want to have firewire (sbp) devices
hung onto da* first, and then USB umass devices.

Even more specifically, I have a drive that I either attach
via firewire on one machine, or via USB on a different box.
I wish this drive to always be da0.  I can connect it to a
suitably ordered uhub slot in order to guarantee all other
USB devices get da1-whatever.  However, it seems that umass
devices get attached to da* before firewire.

As a result, when this drive is attached via firewire to a
machine that has cardreaders and whatnot attached via USB,
some other device shows as da0.

If I were to wire sbp0 to be da0 on that machine, then if
I were to attach it there via USB1/2, it would never be da0
and my fstab would not match.  Therefore, the solution seems
to be to give firewire first dibs at da*, where nowadays umass
gets first pick.


thanks for the enlightenment
barry bouwsma