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Date:      Sun, 5 Sep 1999 09:56:39 +0100 (BST)
From:      Doug Rabson <dfr@nlsystems.com>
To:        Mike Smith <mike@smith.net.au>
Cc:        Peter Wemm <peter@netplex.com.au>, John-Mark Gurney <gurney_j@resnet.uoregon.edu>, "Zach N. Heilig" <znh@thequest.net>, freebsd-current@freebsd.org
Subject:   Re: PNP ids missing in sio.c 
Message-ID:  <Pine.BSF.4.10.9909050954220.2081-100000@salmon.nlsystems.com>
In-Reply-To: <199909050210.TAA08633@dingo.cdrom.com>

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On Sat, 4 Sep 1999, Mike Smith wrote:

> > > I'm curious what can be made of the PNP resource list we get from the BIOS
> > > at boot time...  It lists motherboard resources too, we could probably end
> > > up with a fairly complete map of known resources to avoid.
> > 
> > I bet we can roll another enumerator similar to pnp.c which takes the bios
> > output and turns it into devices. It would mean removing all the probe
> > hints from your kernel config to avoid confusion but apart from that it
> > should work really well.
> 
> This is one reason why I think that the PnP scan should be done 
> _before_ the legacy scan; there are cases where the legacy scan is 
> going to find stuff that the PnP enumerator also knows about.  If the 
> PnP enumerator has already found it, then the legacy scan aborts; in 
> the reverse situation the PnP enumerator has no way of knowing that the 
> device has already been claimed.
> 
> As for the BIOS PnP info; all I'm doing at the moment is scanning for 
> device and compat IDs.  Since the information is formatted in exactly 
> the same fashion as ISA PnP data, I was hoping to actually dump the 
> current pointless scan and hook the BIOS access method into the new PnP 
> code.
> 
> Another argument for making the PnP scan first is that the BIOS 
> identifies a whole pile of "do not go there" regions which you don't 
> want anything, even a legacy device probe, looking at.

Its a difficult problem. If you run the heuristic probes first, then one
of them might pick up a device intended for a pnp driver. On the other
hand if you don't run the heuristic probes first, you have no idea what
resource regions to avoid when allocating resources for pnp devices.

Surely with a working pnpbios *all* devices become pnp devices which
solves the problem quite neatly.

--
Doug Rabson				Mail:  dfr@nlsystems.com
Nonlinear Systems Ltd.			Phone: +44 181 442 9037




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