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

Jesse Barnes jbarnes at virtuousgeek.org
Thu Mar 9 06:54:21 EST 2006

On Wednesday, March 8, 2006 11:26 am, Linus Torvalds wrote:
> But if you have a separate IO fabric and basically two different CPU's
> can get to one device through two different paths, no amount of write
> barriers of any kind will ever help you.

No, that's exactly the case that mmiowb() was designed to protect 
against.  It ensures that your writes have arrived at the destination 
bridge, which means after that point any other CPUs writing to the same 
device will have their data actually hit the device afterwards.  
Hopefully deviceiobook.tmpl makes that clear...


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