Memory barriers and spin_unlock safety

Hollis Blanchard hollisb at
Sat Mar 4 08:18:13 EST 2006

On Friday 03 March 2006 15:06, Benjamin Herrenschmidt wrote:
> The main problem I've had in the past with the ppc barriers is more a
> subtle thing in the spec that unfortunately was taken to the word by
> implementors, and is that the simple write barrier (eieio) will only
> order within the same storage space, that is will not order between
> cacheable and non-cacheable storage.

I've heard Sparc has the same issue... in which case it may not be a "chip 
designer was too literal" thing, but rather it really simplifies chip 
implementation to do it that way.

Hollis Blanchard
IBM Linux Technology Center

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