Re: MTRR & NVTNT

Scott Lampert (fortunato@heavymetal.org)
Thu, 11 Mar 1999 15:29:23 -0500

On Thu, Mar 11, 1999 at 08:35:58PM +1100, Richard Gooch wrote:
> Scott Lampert writes:
>
> > Forgive me if I show my lack of knowledge on the subject, but
> > I've been trying to figure out how to get MTRR working with my
> > Nvidia TNT AGP board in 2.2.3 but it keeps giving me errors such as:
> > mtrr: base(0xe6000000) is not aligned on a size(0xff0000) boundary
> >
> > Of course, I agree, it apparently isn't aligned that way. Does this
> > mean that one cannot use MTRR with the NVidia TNT boards? Looking
> > on a Windows box with the same card it appears to break up the 16
> > megs of video RAM into non-contiguous blocks. I'm not even sure if
> > the Windows drivers are making use of the MTRRs. Anyhow, just
> > thought I'd throw out the question and see if anyone would be kind
> > enough to clue me in. Thanks,
>
> You have a 16 MB card. Why do you try to set the size to 15 MB
> (0xff0000)?
>
> Regards,
>
> Richard....

Doh! You're right of course. Setting it to size (0x1000000) worked
fine. That leads me to another two questions if you have the time:

My X server has this line for video ram:

(--) SVGA: PCI: NVidia Riva TNT rev 4, Memory @ 0xe4000000, 0xe6000000

Does this mean I should have two 8 meg MTRR entries at those base
addresses or just ignore the first one?

And secondly I noticed when I use the VESA fb console, it works fine,
however when it tries to automatically set the MTRR at the 0xe6000000 base
address it incorrectly tries to use size 0xff0000 like I was doing before and
gets the same error. This would appear to be a bug. I know you didn't write
this part of the kernel, but since I'm carboning this to the kernel list I
figured I'd mention it in case it was significant.

Thanks for the clue!
-Scott

-- 
Scott Lampert              | Home Page: http://www.heavymetal.org
<fortunato@heavymetal.org> | PGP Key: finger fortunato@heavymetal.org
"Singe the Hare Hare,      +-----------------------------------------
   dance the Hoochie Koo!"




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