Jamie,
I referenced a great book an an email to Rik Van Reil. It's got a great
explanation of this stuff.
:-)
Jeff
Jamie Lokier wrote:
>
> Jeff V. Merkey wrote:
> > This means it completely unnecessary to assert LOCK# for the unlock
> > case, since there are no ordering issues persay - the other processors
> > are spinning on the lock already and cannot get through.
>
> Yes I know I left out the context. Doesn't change what I'm about to
> say. Erm, this does not appear to address ordering between the spinlock
> and access to _other_ memory locations. I know you're right and your
> information is very interesting, but it doesn't appear to address the
> point... only knowledge of processor ordering tells us that `movb' for
> spin-unlock always flushes prior pending writes before unlocking.
>
> That's something that comes from manuals etc. and indeed, the _bugs_ in
> that show up on the scopes (circa 1994 as you said).
>
> -- Jamie
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