Re: PAT & pmap(9) changes (was Re: CVS commit: src)

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

On Thursday 08 July 2010 14:33:12 Thor Lancelot Simon wrote:
> On Thu, Jul 08, 2010 at 12:12:57PM +0200, Christoph Egger wrote:
> > > > No comments on this last version.
> > >
> > > Some of us scarcely have had time to reply to the second version. :-/
> >
> > It was enough time for code review. I thought, the way how it works
> > was clear after the discussion of the first version stopped.
>
> I didn't see any of the concerns David expressed earlier really addressed
> in any way.

Please explain. Which concerns were not addressed?
Davids questions were "What is PAT?" and "How does PAT work?"
That is what I explained.

> I very much appreciate the work on better support for X86 architectural
> features.  However, this particular change really seems to me to embed
> a lot of X86 quirks in the MI VM system.

Please itemize the x86 quirks you see.

> I don't like that.  The API to the MI parts of the NetBSD kernel should not
> be dictated by oddities of the X86 MMU or memory controllers.

I agree with you. That is why I encouraged you all to a discussion
in this mail:

http://mail-index.netbsd.org/tech-kern/2010/05/19/msg008183.html

I made two statements:

"Martin asked in a later mail if we can move the discussion
to x86-only mailing lists. Well, not quite since I add
MI PMAP flags to uvm/uvm_pmap.h:"

"Another point to discuss is whether the new MI pmap flags
make sense to have on non-x86 ports."

Noone came actually up with any non-x86 concerns. So when
discussion stopped I really really thought all is fine.
Just the code needs some refactoring/refinements and that's it.

Christoph