Re: Linux 2.6.39-rc3

[Joerg Roedel]

On Fri, Apr 15, 2011 at 10:26:34AM +0200, Michel Dänzer wrote:
> On Don, 2011-04-14 at 23:09 +0200, Joerg Roedel 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.
> > 
> > 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.
> 
> Wasn't the working theory that the problem occurs if those two values
> aren't the same?

Yes it is, but this doesn't seem to be problematic on all readeon GPU
chips.

	Joerg

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