Re: use of volatile in iounmap()?

[H. Peter Anvin]

Sam Ravnborg wrote:
> > >
> > Yes.  The use of volatile in a function prototype like this means that 
> > it is valid to pass a volatile pointer to that function -- in other 
> > words, we're telling gcc that we're not going to do anything with the 
> > pointer that is invalid for a volatile pointer.

> If I understand you correct then it is then not wrong to say
> that we have the argument volatile to avoid warnings from gcc
> when we pass a volatile pointer.
>
> And then having the pointer marked volatile put a few restrictions
> on iounmap().

Correct.

> > A lot of the "volatile considered harmful" stuff that has been bandied 
> > about is explicitly about marking *data* items volatile (it does have 
> > its uses, but it's easy to get wrong); Linus has explicitly made the 
> > distinction between volatile *data* and volatile *operations*.
>
> Yes - but unfortunately the volatile-considered-harmful.txt
> does many deal with the data part.

Yes, it does.

	-hpa

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