Re: Ordering between PCI config space writes and MMIO reads?

Matthew Wilcox
2006-10-31T19:58:11Z

On Tue, Oct 31, 2006 at 11:53:02AM -0800, Roland Dreier wrote:
> > Here's what I don't understand: according to PCI rules, pci config read
> > can bypass pci config write (both are non-posted).
> > So why does doing it help flush the writes as the comment claims?
>
> No, I don't believe a read of a config register can pass a write of
> the same register. (Someone correct me if I'm wrong)

I don't see anything in the PCI spec which forbids it, but I would
expect that hardware designers don't actually do that in practice.