On Wed, 2018-03-28 at 11:55 +0200, Arnd Bergmann wrote: > > powerpc and ARM can't quite make them synchronous I think, but at least > > they should have the same semantics as writel. > > One thing that ARM does IIRC is that it only guarantees to order writel() within > one device, and the memory mapped PCI I/O space window almost certainly > counts as a separate device to the CPU. That sounds bogus. > In the absence of an enforced global synchronization during an I/O port > access, that means writel() and outb() can be reordered before they arrive > at a device in theory. Again, this rarely matters in practice, but I think it > makes sense to document the less strict behavior here, given that we have > common hardware that can't provide x86 compatible semantics. Can't you put some kind of super heavy handed barrier in inX/outX ? These things are never going to be performance sensitive anyway... Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
