On 12/01/2010 04:58 AM, april wrote:
hi all:
I have a question:
If a BO in VRAM (WC) evict to SYS memory(may be cached), and user
process still can access it event it is in SYS memory (may be cached)
.
when this BO volidate to VRAM, It seems "ttm_bo_handle_move_mem" not
flush cache (If evict to SYS memory with cached).
But flush cache is needed, If driver use DMA to handle BO
move(SYS->VRAM), should "ttm_bo_handle_move_mem" handle this? or
driver do it in "driver->move_notify" before "driver->move" called?
April, in order to understand your proble, Can you be a bit more
specific about.
1) Which cache should be flushed? Cpu cache or GPU cache.
2) Why should it be flushed? For CPU caches, TTM only flushes when
transitioning the same page from cached to write-combined. If you use
DMA from system memory to VRAM, and need to flush the system pages
before performing the DMA operation, that should be done in the driver
move function.
/Thomas
Thanks
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