Re: Opinion on ordering of writel vs. stores to RAM

From: Benjamin Herrenschmidt
Date: Sat Sep 09 2006 - 03:24:28 EST



> I suspect the best thing at this point is to move the sync in writeX()
> before the store, as you suggest, and add an "eieio" before the load
> in readX(). That does mean that we are then relying on driver writers
> putting in the mmiowb() between a writeX() and a spin_unlock, but at
> least that is documented.

Well, why keep the sync in writel then ? Isn't it agreed that the driver
should use an explicit barrier ? Or did I misunderstand Linus ?

Ben.


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