KMS and TTM questions

[James Simmons]

> >> > Thats fine as long as you don't want to do acceleration or object
> >> > migration between GTT
> >> > and VRAM type memory. Now I expect when you give out this advice you
> >>
> >> Yes but the VIA doesn't if I recall correctly have any 'VRAM type memory'.
> >> It's all effectively in the GART with the 'stolen' pages preloaded into
> >> the translation tables by the BIOS at vga init time.
> >>
> >> It has fake VRAM type memory but thats really an illusion (although one
> >> the driver seems to like to keep up). The GEM changes do mean you can
> >> plug the existing allocator in the VIA driver into GEM directly. Whether
> >> that would be a good idea or not given the other things you then need to
> >> do I don't know - but it does seem to be me to be a stepping stone in the
> >> right direction that is much easier to make ?
> >
> > That is correct. In fact the via driver detects what type of system ram is
> > used so I can limit what resolutions are supported. Its possible that the
> > memory doesn't have the bandwidth to support a very large resolution on
> > older systems.
> 
> Is vram actually handled via a scatter/gather page table or is it just
> a pointer to a contiguous chunk of stolen system memory at the top of
> ram?

Stolen chuck. At the same time newer chipsets, VX900, have pcie gart 
table to move data to and from the "vram".