[Nouveau] NV50: the tiled buffer object eviction problem

[Ben Skeggs]

On Sat, 2009-12-26 at 03:13 +0100, Maarten Maathuis wrote:
> In short, we move out the low level content of a buffer object. In the
> case of textures and such this is utterly useless. Still it is
> accessed, because ttm sees no problem in using PL_SYSTEM or PL_TT
> memory. What is the best way to let ttm know we don't really
> appreciate that? A custom memory to evict to that cannot be mapped
> maybe. Or an extension of PL_SYSTEM or PL_TT. Share your ideas.
For GPU access it isn't an issue, userspace knows it needs to use VRAM
and won't set GART as an allowed memtype.

For CPU access, we should trap this in the fault handler and revalidate
the buffer into VRAM.

That's my thoughts :)

Merry Xmas!
Ben.
> 
> Maarten.
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