Re: [PATCH 2/3] x86_64: Define 128-bit memory-mapped I/O operations

On 08/22/2012 08:51 AM, Ben Hutchings wrote:

quoted

FWIW can you even guarantee to do an atomic 64bit PCIe transfer
on many systems (without resorting to a dma unit).

On any architecture that implements readq and writeq these had better be
atomic.

Sorry, you fail.  There are definitely systems in the field where 
readq() and writeq() are implemented, because the CPU supports them, 
where the fabric does not guarantee they are intact.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.