[PATCH] Document Linux's memory barriers [try #2]

[David Howells]

Linus Torvalds <torvalds at osdl.org> wrote:

> Actually, since the different NUMA things may have different paths to the 
> PCI thing, I don't think even the mmiowb() will really help. It has 
> nothing to serialize _with_.

On NUMA PowerPC, should mmiowb() be a SYNC or an EIEIO instruction then? Those
do inter-component synchronisation.

David