multiple separate pci bridges ...

Benjamin Herrenschmidt benh at
Mon Jan 19 22:41:19 EST 2004

On Mon, 2004-01-19 at 21:08, Geert Uytterhoeven wrote:
> On Mon, 19 Jan 2004, Benjamin Herrenschmidt wrote:
> > > I am returning 0 for all of function 0. I dropped the whole struct
> > > pci_dev ressource thingy, and they are well nullified. My limited
> > > understanding of those pci issues let me make a guess though. I think
> > > that either the stuff in the struct pci_dev is set later on (the BARs
> > > are modifiable i think), or those values are read from the struct
> > > pci_dev before i nullify them.
> >
> > pci_dev resources are read from the BARs and the sizing mecanism
> > uses the BARs too (you should filter out writes too btw). If you
> > properly filter things out, there should be no problem.
> So shouldn't reads from the BAR return -1 instead of 0, and writes be ignored?

Writes have to be ignored, I don't remember if an unused BAR should
return 0xffffffff or 0 (check the spec). (The call shall not fail,
the BAR space has to be implemented).


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