pci error recovery procedure

Linas Vepstas linas at austin.ibm.com
Wed Sep 6 04:50:20 EST 2006

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 ... 


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