Re: Linux 2.6.39-rc3

From: Andreas Herrmann
Date: Fri Apr 15 2011 - 10:49:40 EST

On Thu, Apr 14, 2011 at 05:34:46PM -0400, Alex Deucher wrote:
> On Thu, Apr 14, 2011 at 5:09 PM, Joerg Roedel <joro@xxxxxxxxxx> wrote:
> > On Thu, Apr 14, 2011 at 10:28:43AM -0400, Alex Deucher wrote:
> >> On Thu, Apr 14, 2011 at 4:56 AM, Joerg Roedel <joro@xxxxxxxxxx> wrote:
> >> > And this makes a difference, with this change on-top of -rc3 the box boots
> >> > fine. So there seems to be some dependency between the GART base and the GTT
> >> > base even when they are in different address spaces.
> >> >
> >> > Alex, can you comment on this?
> >>
> >> As Dave said, they are completely different addresses spaces.  You
> >> could put the GPU aperture at 0 if you wanted (in fact we do on some
> >> chips).  Perhaps there's some strange interaction with the nb gart
> >> since the nb gart on that chipset was designed to be used for graphics
> >> and the rs780/880 can be configured to use an agp aperture.
> >> Unfortunately, I'm not that familiar with the nb gart.
> >
> > Actually, the nb gart is part of the cpu. It is part of the cpu north
> > bridge and can translate io and cpu accesses. In fact, it is a remapper
> > of physical memory addresses.
> I know what it's for. In the IGP graphics chip is also part of the
> north bridge, but it may not be related at all.
> >
> > The problem seems to be related to specific gpu chips. On another
> > notebook with an hd3000 card gtt and the nb gart aperture are both on
> > 0xa0000000 too but the box works fine. I havn't tested with an hd5000
> > yet. The failing notebook has an hd4200 mobility.
> What exact model is the hd3000? Is it IGP GPU or a discrete GPU? It
> it's an IGP, it's identical to the hd4200 programming-wise.

BTW, first of all the other notebook had a different CPU (it's family
0fh and Joerg's is family 10h). So different CPUs different GARTs
different issues ;-)

(Furthermore for CPU family 0fh reporting of GartTblWalk errors is
already switched off in arch/x86/kernel/cpu/mcheck/mce.c.)

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