[OpenBIOS] PCI setup code

[David Christensen]

Actually, another method exists in most BIOS implementations that allows the
OS to read a table and know the PCI IRQ routing.  If you check the site
http://www.microsoft.com/HWDEV/busbios/PCIIRQ.htm you'll see the
specification.  Basically, search the BIOS for the string 'PIR$'.  What
follows is a description of the PCI IRQ routing for all of the embedded PCI
devices and all slots.  You MUST have this info to set up PCI cards
correctly, and this information can only come from the manufacturer of the
motherboard.  You'll have to copy this table from the original BIOS in order
to configure your system.

Dave

-----Original Message-----
From: owner-openbios at elvis.informatik.uni-freiburg.de
[mailto:owner-openbios at elvis.informatik.uni-freiburg.de]On Behalf Of
Marcus Gossner
Sent: Tuesday, March 28, 2000 11:59 PM
To: 'openbios at freiburg.linux.de'
Subject: RE: [OpenBIOS] PCI setup code


Ronald G. Minnich wrote:
>
>> What problems exactly are you having in PCI setup?  I've been messing
>> around in that area lately and can help...
>
>
>first, in 2.2.10, it doesn't do ANY configuration of memory-addressable
>BARs. Second, it doesn't do any IRQ assignment. If 2.3 fixes this then
>I'll just cut over.
>
>ron

The IRQ assignment can't be done in the operating system. It depends on the
wireing on your board and therefore it is done in BIOS. You can check the
IRQ assignment with your original BIOS:

1. Select fixed ISA IRQs for PCI IRQs
   e.g.  PCI INTA = IRQ  9
         PCI INTB = IRQ 10
         PCI INTC = IRQ 11
         PCI INTD = IRQ 12
2. Put PCI cards in all slots
3. Boot something and look into PCI configuration space
   If for example the card in PCI Slot 1 got IRQ 11 you know now this Slot
uses PCI INTC.

Please remember to set up your chipset correctly to select with PCI IRQ use
with ISA IRQ. Then you can assign this IRQs to your PCI Slots.

Marcus

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