wmb vs mmiowb

[Linus Torvalds]

On Thu, 23 Aug 2007, Nick Piggin wrote:
> 
> OK, but we'd have some kind of functions that are called not to
> serialise the CPUs, but to serialise the IO. It would be up to
> the calling code to already provide CPU synchronisation.
> 
> serialize_io(); / unserialize_io(); / a nicer name

We could call it "mmiowb()", for example?

Radical idea, I know.

> If we could pass in some kind of relevant resoure (eg. the IO
> memory or device or something), then we might even be able to
> put debug checks there to ensure two CPUs are never inside the
> same critical IO section at once.

We could certainly give it the spinlock as an argument.

		Linus