AGPGART driver for ArticiaS - ioremap() problem

Gerhard Pircher gerhard_pircher at
Thu Jan 19 19:50:43 EST 2006

> > Hmm, I'm not sure what value agp_bridge->gart_bus_addr should have. The
> > BIOS doesn't setup it and the VIA AGPGART driver even reads it out from
> > the northbridge's registers! Where does the value for
> > agp_bridge->gart_bus_addr come from? For now it is set to 0x0, which
> > would require the modification in drm_vm.c!?
> Well... this is where you AGP aperture will be in bus space.. you'd
> rather know what to do with it to do a driver...
I'm afraid so. :)

> > :) The driver seems to work better with cant_use_aperture set to 1, so
> > I leave it as it is. BTW: What's the meaning of needs_scratch_page?
> Well, set to 1 would mean the aperture isn't accessible on the CPU
> space. It might seem to work better either because indeed that is the
> case... or simply because you put it in a wrong place (ie 0 !) There
> must be a chipset register somewhere that tells you where the aperture
> is no ?
I set the AGP aperture base register and agp_bridge->gart_bus_addr to
0x01000000 (>=16MB) (trial and error :-) and it seems to work with
cant_use_aperture=1 (and without the modification in drm_vm.c). Even the X
server maps all the data to this address and displays a login screen.
Unfortunately it always freezes in. I guess this is due to the missing GART
flush functionality. So I have to get this working first.



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