Re: Why *not* rmap, anyway?

[Daniel Phillips <phillips@bonn-fries.net>]

On Tuesday 07 May 2002 21:23, Rik van Riel wrote:
> On Tue, 7 May 2002, Christian Smith wrote:
> 
> > >> If not the Mach pmap layer, then surely another pmap-like
> > >> layer would be beneficial.
> > >
> > >How about the one we already have?
> >
> > I don't like using a data structure as an 'API'. An API ideally gives
> > you an interface to what you need to do, not how it's done. Sure, APIs
> > can become obsolete, but function calls are MUCH easier to provide
> > legacy support for than a large, complex data structure.
> 
> OK, this I can agree with.
> 
> I'd be interested in working with you towards a way of
> hiding some of the data structure manipulation behind
> a more abstract interface, kind of like what I've done
> with the -rmap stuff ... nothing outside of rmap.c
> knows about struct pte_chain and nothing should know.
> 
> If you could help find ways in which we can abstract
> out manipulation of some more data structures I'd be
> really happy to help implement and clean up stuff.

The most obvious place to start are the page table walking operations, of
which there are a half-dozen instances or so.  Bill started to do some
work on this, but that ran aground somehow.  I think you might run into
the argument 'not broken yet, so don't fix yet'.  Still, it would be
worth experimenting with strategies.

Personally, I'd consider such work a diversion from the more important task
of getting rmap implemented.

-- 
Daniel
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