Subject: Re: Another changer, another changer problem
To: David Maxwell <>
From: Dave Huang <>
List: current-users
Date: 10/05/1998 16:51:56
On Mon, 5 Oct 1998, David Maxwell wrote:
> I have a feeling that certain BIOS' (What the plural of BIOS? BIOSae?) may
> not keep these constant, or for that matter that different BIOS sets will
> pick the same numbers if you swap a motherboard. I also don't know how to
> find these numbers out except by booting multiple times and adding one
> card each reboot.

On the systems I've seen so far (two ASUS boards and a couple of
Gateways that use Intel boards), the PCI device number correspond to the
physical slots on the board. For example, my current board, an ASUS
P55T2P4 has:

pchb0 at pci0 dev 0 function 0
pcib0 at pci0 dev 7 function 0
pciide0 at pci0 dev 7 function 1: Intel 82371SB IDE Interface (PIIX3) (rev. 0x00)
uhci0 at pci0 dev 7 function 2: Intel 82371SB USB Host Controller (PIIX3) (rev. 0x01)
ncr0 at pci0 dev 9 function 0: ncr 53c875 fast20 wide scsi
ep0 at pci0 dev 10 function 0: 3Com 3c595-TX Ethernet
ncr1 at pci0 dev 11 function 0: ncr 53c810a fast10 scsi
Matrox MGA Millennium 2064W ("Storm") (VGA display, revision 0x01) at pci0 dev 12 function 0 not configured

Devs 0 and 7 are on the board itself, dev 9 is the leftmost slot, 10 the
next one, 11 the next, and 12 the rightmost slot. I've never seen the
numbers change from BIOS updates or changes in the BIOS settings... they
look pretty constant to me. I wouldn't be at all surprised if a
different type of motherboard would number the slots differently, but
I don't think it's unreasonable to have to tweak your kernel a bit when
swapping motherboards.
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