[RFC] Fix full memory barrier on SPARC-V8

David Miller davem@davemloft.net
Tue Jun 28 08:05:00 GMT 2011


From: Geert Bosch <bosch@adacore.com>
Date: Mon, 27 Jun 2011 23:17:18 -0400

>> \You then go on to speak about LEON, does LEON implement PSO?
> No, I'm not talking about PSO anywhere or SPARCv9 anywhere. 
> Just plain old SPARCv8, using the TSO model. This requires a
> load-store instruction to guarantee a full memory barrier.
> 
> I'm not making this up, that is why I refer to the examples in
> the SPARC v8 architecture manual that specifically state that
> SWAP instructions need to be used instead of store instructions
> to make Dekker's algorithm work.

All v8 processors that I am aware of implement strong consistency, and
if so discussions about TSO are not relevant.  Is LEON an exception?

Let's clarify something, did you run your testcase that triggered this
bug on a v8 or a v9 machine?



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