Lennart Augustsson <augustss@cs.chalmers.se> writes:

> So what is supposed to happen when you claim to have a PnP aware OS?
> Should BIOS stop configuring PCI devices?  That sounds like a
> violation of the spec.

Bingo.

I think the whole "PnP aware OS" thing is a crock.  Either the BIOS
does it, or every OS has to, and the BIOS is the right place for PCI,
where it is hard to find cards that will conflict.

With ISA PnP, however, that tends to change...  Some BIOS cannot
handle ISA PnP, while others do it wrong, ignore conflicting cards, etc.
Some even do worse, and allow cards to conflict.

Do we need code to initialize a PCI bus?  Sure, it'd be cool, but not
for machines with a firmware/BIOS that can do it.  Do we need code that
will _correctly_ configure ISA PnP cards?  Yes.  Should our code _first_
look at the BIOS configuration info?  Yes.  Do we do that?  No.

That is, for instance, why my PnP modem breaks.

The BIOS configures it at com2's address.  NetBSD finds it on the ISA
bus (which it is, of course) at com2's address.  Then ISA PnP
comes along and resets all the cards.  My modem is lame, and _has_ to be
at com2's address.  So, ISA PnP fails to configure it -- something else
is already there -- and now the modem is in a reset state, and any access
to /dev/tty01 (say, the ttyflags in /etc/rc) locks the machine up tight.

--Michael