pci error recovery procedure

[Linas Vepstas]

On Mon, Sep 04, 2006 at 07:03:12PM +1000, Benjamin Herrenschmidt wrote:
> 
> > As you know, all functions of a device share the same bus number and 5 bit dev number.
> > They just have different 3 bit function number. We could deduce if functions are in the same
> > device (slot).
> 
> Until you have a P2P bridge ...

And this is not theoretical: for example, the matrox graphics cards:

0000:c8:01.0 PCI bridge: Hint Corp HB6 Universal PCI-PCI bridge (non-transparent mode) (rev 13)
0000:c9:00.0 VGA compatible controller: Matrox Graphics, Inc. MGA G400 AGP (rev 85)

Now, I could have sworn there was another device behind this bridge, 
some serial or joystick controller or something, although this
particular card doesn't seem to have it.

------
It's not clear to me what hardware may show up in the future. 
For example, someone may build a 32x PCI-E card that will act 
as a bridge to a drawer with half-a-dozen ordinary PCI-X slots 
in it. This is perhaps a bit hypothetical, but changing the API 
will make it harder to implement eror recovery for such a system.

FWIW, there is at least one pSeries system in the lab which has
several hundred PCI slots attached to it, although I've never 
done testing on it. Hmm. Maybe its time I did ... 

--linas