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Date:      Fri, 16 Dec 2005 11:23:15 -0800
From:      Eric Anholt <eta@lclark.edu>
To:        Jung-uk Kim <jkim@FreeBSD.org>
Cc:        "O. Hartmann" <ohartman@mail.uni-mainz.de>, freebsd-amd64@FreeBSD.org
Subject:   Re: device drm with PCIe?
Message-ID:  <1134760995.1404.88.camel@leguin>
In-Reply-To: <200512161358.34963.jkim@FreeBSD.org>
References:  <43A1636A.6030108@mail.uni-mainz.de> <200512161230.41499.jkim@FreeBSD.org> <1134757662.1404.81.camel@leguin> <200512161358.34963.jkim@FreeBSD.org>

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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.=20
> > 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.
>=20
> Ah, Eric is correct about the Intel part.  But it was amd64 thread, so=20
> 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?

--=20
Eric Anholt                                     eta@lclark.edu
http://people.freebsd.org/~anholt/              anholt@FreeBSD.org

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