Re: fix CONFIG_HIGHPTE

[Andrew Morton <akpm@zip.com.au>]

Anton Blanchard wrote:
> 
> 
> > We're piling more and more crap in there to support these pte_chains.
> > How much is too much?
> >
> > Is it likely that large pages and/or shared pagetables would allow us to
> > place pagetables and pte_chains in the direct-mapped region, avoid all
> > this?
> 
> On ppc64 shared pagetables will require significant changes to the way
> we handle the hardware hashtable. So add that to the "more and more crap
> in there to support these pte_chains"

Last I heard, pagetable sharing wasn't working out too well
because they all get unshared.
 
> Will shared pagetables be a requirement or can we turn it on per arch?

It's doubtful if per-arch would be an option.

How about this?

- We rely on large pages to solve the Oracle problem

- I'll do pte_chain_highmem and keep that and Bill's patch under test
  in my tree on a wait-and-see basis.  Could go ahead and submit it
  but it's all more complexity, and it'd be nice to actually pull
  something out for a change.

- We'll continue to suck for the University workload.