Re: user-mode port 0.44-2.4.7

[Alan Cox]

> > This is not a gcc issue. Even if gcc _were_ to generate bad code, the
> > global volatile _still_ wouldn't be the correct answer.
> 
> I think his worry is the pedantic reason that without the volatile gcc is
> allowed to write code that chokes and dies if xtime happens to change in a
> volatile manner.  The example given earlier was:

Make the volatility explicit where it is needed, either to express a barrier
with barrier() or an assignment as in

	foo = (volatile)xtime

This makes it clear where the barriers are and avoids unpleasant
optimisation hits elsewhere.

Alan