Re: hammer: MAP_32BIT

["H. Peter Anvin" <hpa@zytor.com>]

Followup to:  <1052597418.1881.2.camel@lapdancer.baythorne.internal>
By author:    David Woodhouse <dwmw2@infradead.org>
In newsgroup: linux.dev.kernel
>
> On Sat, 2003-05-10 at 02:48, Andi Kleen wrote:
> > > Oh, and please rename MAP_32BIT to MAP_31BIT.  This will save nerves on
> > > all sides.
> > 
> > I bet changing it will cost more nerves in supporting all these people
> > whose software doesn't compile anymore. And it's not really a lie. 2GB 
> > is 32bit too.
> 
> If that's _really_ an issue, then also provide MAP_32BIT which does what
> its name implies. 
> 
> Anyone who was using MAP_32BIT in the knowledge that it really limits to
> 31 bits gets the breakage they deserve for not reporting and fixing the
> problem at the time.
> 

Agreed.

That being said, I think a more flexible scheme is called for; I still
would like to suggest the MAP_MAXADDR and MAP_MAXADDR_ADVISORY flags
that I mentioned earlier.

If people really want to retain the (rarely used) suggestion address,
I'd suggest making the address argument a pointer to a structure:

struct map_maxaddr {
	void *search;	/* Suggestion address */
	void *min;	/* Lowest acceptable address */
	void *max;	/* Maximum acceptable address */
};

... however, it seems like overkill to me.

	-hpa
-- 
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