Re: DRM memory manager on cards with hardware contexts

[Benjamin H. <be...@ke...>]

> I don't think so. 
> We are not doing vram yet in the TTM code, but I think a general
> "eviction" would consist of 
> 
> 1) locking mmap_sems for all processes mapping the buffer.
> 2) zap the page table. Any attempt to access will be blocked by
> mmap_sem in nopage().
> 3) Copy contents from vram to system using either PCI SG or
> video-><blit>->AGP-><flip>->system.
> 4) Wait for completion.
> 5) release the mmap sem. The page table will be refilled using
> nopage().

On Cell, for SPU mappings, we don't scan through all processes mapping
it, we use umap_mapping_range() which does it. However, after
double-checking, i have some doubts about the locking so I'm trying to
clarify that and I'll come back to you wether it's actually a viable
solution or not.

Ben.