On 10/04/2011 01:07 AM, Alan Cox wrote:
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.
VRAM memory (at least on the older unichromes) is taken from on-board
RAM and set up by the BIOS, and from a device programmer's point of view
works like a discrete card VRAM, and is *not* part of the GART.
On some devices (K8M800) , the VRAM pages could be accessed by the CPU
directly at the top of VRAM, which was substantially faster.
There is a fully functional unichrome DRM on top of TTM, that together
with the 3D driver in mesa's openchrome branch worked like a charm (even
outperformed Intel's i965 with identical CPU at the time).
Problem was that it was not backwards compatible with via's old drm.
It should serve as a good starting point though, if I can remember where
I put it....
/Thomas
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