Re: [openib-general] Ordering between PCI config space writes and MMIO reads?

Roland Dreier
2006-10-25T14:05:12Z

> I'm not sure that can work either. The PCI-X spec is very clear, you
> must wait for a non-posted completion if you care about order. Doing a
> config read in the driver as a surrogate flush is not good enough in
> the general case. Like you say, a pci bridge is free to reorder all
> in flight non-posted operations.

No, hang on. Nothing can reorder a dependent read to start after a
write that it depends on, can it? So a config read of PCI_COMMAND
can't start until the completion of a config write of the same
register, right?

- R.