Re: [patch] smp-2.3.30-A1, mb(), wmb(), rmb()

Alan Cox (alan@lxorguk.ukuu.org.uk)
Thu, 25 Nov 1999 12:00:28 +0000 (GMT)

> * And yes, this is required on UP too when we're talking
> * to devices. Note that these primitives deal with operation
> * ordering, not atomicity.

This doesn't make a lot of difference if any. The PCI bridge has write
buffers and PCI doesn't claim to be synchronized in any way. PCI does have
strict write ordering so that is safe but its ordering relative to ram is not
deterministic.

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