RE: Subsystem IDs, again

["John R Pierce" <pierce@scruznet.com>]

Um, actually, what I meant was these chips actually 'pigeon'
hole the subsystem ID configuration reads and reflect them into
a ROM BIOS read of some fixed offset...  I guess I didn't phrase that
well...

When you read the configuration address for the subsystem/vendor ID info,
the chip actually reads the bios rom itself.  Yes, you are correct, this
won't work on a motherboard solution...  But a motherboard solution
by definition can have the system bios pre-load these registers.  Even a 
ACPI system will invoke the motherboard bios on power-back-up...

-jrp

----------
From: 	Kevin D. Davis
Sent: 	Friday, August 02, 1996 7:56 AM
To: 	'PCI SIG'; 'John R Pierce'
Subject: 	RE: Subsystem IDs, again

Please don't count on the BIOS to load up cards.

Once ACPI comes along, there is a good chance that your boot time BIOS 
won't get control after a power transistion.  There MIGHT be a chance for 
your driver to remember the ids, but that's not entirely clear to me.

As for your chip reading directly from the BIOS, for chips I put in the 
notebook, I merge the BIOS into the system BIOS.  Thus, MY core logic chip 
controls access to the BIOS, not your chip.  So, if you use this approach, 
make sure there is a cheap solution for notebooks.

Kevin

----------
From:  John R Pierce[SMTP:pierce@scruznet.com]
Sent:  Friday, August 02, 1996 1:20 AM
To:  Mailing List Recipients
Subject:  RE: Subsystem IDs, again

Peter wrote...
>A serial ROM is the only solution for expansion cards, but I don't think 
it
>violates the spirit or the letter of this requirement to use a write to 
the
>user config space to set up the subsystem ID on motherboard devices, and
>this would save motherboard designers the need to have one SROM per PCI
>device.

Actually, there is an alternative for devices with bios roms (mainly 
graphics
and scsi adapters)...  The subsystem ID registers can be mapped to fetch
from the bios rom in parallel...

-jrp


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