device drm with PCIe?

[Eric Anholt]

On Fri, 2005-12-16 at 13:58 -0500, Jung-uk Kim wrote:
> On Friday 16 December 2005 01:27 pm, Eric Anholt wrote:
> > On Fri, 2005-12-16 at 12:30 -0500, Jung-uk Kim wrote:
> > > On Thursday 15 December 2005 07:36 am, O. Hartmann wrote:
> > > > Normally 'device drm' is only useable in conjunction with
> > > > 'device agp'. A lot of amd64 based boxes now use PEG slots for
> > > > their graphics accelerators. Is it possible to utilize 'drm'
> > > > with PCIe devices?
> > >
> > > Yes.  It should work, at least in theory. ;-)
> > >
> > > > Does device agp has any effect on PCIe graphics accelerators?
> > >
> > > No.  You don't need it for PCI-Express controller.
> >
> > Now, this is stuff I don't 100% understand, but what I've figured
> > out so far is that for graphics, you're going to need a GART
> > somewhere.  For their PCIE cards, ATI deals with this by doing
> > essentially the old PCIGART method but tweaked, in lieu of AGP. 
> > Intel's PCIE graphics, on the other hand, has a GART on their chips
> > that is basically the same thing as their previous AGP GARTs, at
> > least in terms of programming.  So we expose their gart through the
> > agp device still, even though the chipset may be PCIE.
> 
> Ah, Eric is correct about the Intel part.  But it was amd64 thread, so 
> I just assumed... :-(

And now, for extra complication, we've got EM64Ts on i915
motherboards :)

It also seems to me like we ought to be able to use the internal GART on
real amd64s to avoid the card's PCIGART-ish method for PCIE radeons,
right?

-- 
Eric Anholt                                     eta at lclark.edu
http://people.freebsd.org/~anholt/              anholt at FreeBSD.org
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