Re: [PATCH 2/2] ix86: atomic64 assembly improvements

[H. Peter Anvin]

On 01/19/2012 06:50 AM, Jan Beulich wrote:
> > It doesn't have anything to do with caches on or off.
>
> How does it not? If any part of the bus topology is only 32 bits wide,
> a 64-bit read or write simply can't be executed atomically without
> asserting LOCK#.

If any part of the bus topology is only 32 bits wide, you're not talking 
to memory on anything newer than a 486.

LOCK to I/O devices is unreliable on any machine (a lot of northbridges 
simply drop LOCK on the floor).

	-hpa

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