Re: Flushing writes to PCI devices

Alan Cox
2006-09-21T18:21:47Z

Ar Iau, 2006-09-21 am 11:14 -0700, ysgrifennodd Bryan O'Sullivan:
> Yes. If your device requires that writes to some locations in MMIO
> space be performed in a specific order, you must explicitly do this in
> your driver. Intel CPUs will flush posted writes out of order, for
> example.

According to the docs I have here if the pci target area is
prefetchable/postwritable or has MTRRs set specifically to do this (eg
video ram).

There is no ordering guarantee between PCI and main memory however.

Alan