On Mon, 2008-05-26 at 19:28 -0700, David Miller wrote:

quoted

But heh, it's you who was telling me that it would be a bad

engineering

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decision and we had to make everybody look like x86 & fully

ordered :-)

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I decided to agree back then and stuck all those nasty heavy

barriers

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in the powerpc variants of readl/writel/...

I still believe this.

It's just another complicated thing for driver authors to get wrong.
The other side of the coin is of course the cost.

The only thing I am absolutely sure of is that we should make a
decision fast, document it, and just stick to it.

Yes. As it is today, tg3 for example is potentially broken on all archs
with newer gcc unless we either add "memory" clobber to readl/writel or
stick some wmb's in there (just a random driver I picked).

So Linus, what is your take on that matter ?

Cheers,
Ben.