Probing PCI devices not detected by BIOS

[Ketrien I. Saihr-Kesenchedra]

M. Warner Losh wrote:

>In message: <415EC35E.6050602 at jonny.eng.br>
>            João Carlos Mendes Luís <jonny at jonny.eng.br> writes:
>:      My problem: I have an old ASUS P2B-DS motherboard based server, and want to 
>: use a Realtek 8169 Gigabit LAN Card with it.  But the BIOS does not detect the 
>: LAN card, I don't know why.  If I put the card in another computer, it is 
>: detected perfectly.  Unless this is a hardware incompatibility problem, I would 
>: expect FreeBSD to do a better job than the old BIOS.
>
>Chances are good that you might have a problem.  I have a few devices
>that don't appear on one of my machines because the machines are too
>old and not compliant with the latest PCI standards.  I also have one
>cardbus card that refuses to work on some machine due to, I think, bad
>(no?) 3.3V power.
>  
>
There are currently three PCI standards, not including PCI-X. PCI2.1, 
PCI2.2, PCI2.3. (Again, not including PCI-X, this is only 32bit/33MHz.) 
On top of this, you have three voltage standards; PCI 5V, PCI3.3V, and 
PCI-Universal (3.3/5.) These are the -keying- of the slots. So I got out 
the PCI 2.3 specs, go to pp185. A PCI 2.3 slot is keyed at the front 
(towards the front of the case), as the P2B-DS is, and is 5V. A PCI 3.3V 
slot is keyed towards the rear (towards the I/O panel). Then there's PCI 
Universal; this a card-only specification, which has a double-keyed card 
(keyed front -and- rear) to be inserted in 3.3V or 5V slot. A 
universally keyed card should support either 3.3V -or- 5V normally.
The Realtek 8169's I've seen are keyed universal, but is specifically a 
PCI 2.2 or later 3.3V card. A universal keyed PCB is apparently cheaper 
to make than a properly keyed card. The Asus P2B-DS is, as far as I have 
been able to find, a PCI 2.1 board.

-ksaihr