Re: Improved DRM support for cant_use_aperture platforms

[David Mosberger]

>>>>> On Tue, 13 May 2003 17:33:47 +0400, Ivan Kokshaysky <[e-mail]> said:

  Ivan> On Mon, May 12, 2003 at 06:09:16PM -0700, David Mosberger
  Ivan> wrote:
  >> OK, I believe the only other architecture that sets
  >> "cant_use_aperture" is Alpha.

  Ivan> Note that some Alphas may have "cant_use_aperture" cleared.

"Interesting".

  Ivan> I mean Nautilus - unfortunate product of Athlon northbridge
  Ivan> and EV6 interbreeding... I've just managed to get agpgart
  Ivan> working to some degree on one of these beasts (UP1500), but
  Ivan> with so many ugly and fragile hacks that I'm not sure that I
  Ivan> ever want to submit this. ;-)

If cant_use_aperture isn't set, my patch won't help, but it shouldn't
hurt anything either.  I.e., you should be no worse off than before.

What's the nature of those "ugly and fragile" hacks?  Are you saying
that CPU accesses to AGP space aren't remapped in the "normal" (PC)
way?  Or is it something entirely different?

  >> I asked some Alpha folks several months ago about my patch, but
  >> never got a conclusive answer.  IIRC, on Alpha the physical
  >> address itself determines cacheablity.  If so, we can use
  >> PAGE_KERNEL (which is universal) instead of PAGE_KERNEL_NOCACHE.

  Ivan> Yes.

Thanks for confirming.

	--david