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Add additional explanation of DRM_BO_FLAG_CACHED_MAPPED before I forget again.

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Eric Anholt 2008-01-07 13:10:50 -08:00
parent ac6b3780c8
commit 44a9fa8cc6
1 changed files with 8 additions and 1 deletions
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9
shared-core/drm.h
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@ -705,7 +705,14 @@ struct drm_fence_arg {
*/
#define DRM_BO_FLAG_NO_MOVE (1ULL << 8)
/* Mask: Make sure the buffer is in cached memory when mapped
/* Mask: Make sure the buffer is in cached memory when mapped. In conjunction
* with DRM_BO_FLAG_CACHED it also allows the buffer to be bound into the GART
* with unsnooped PTEs instead of snooped, by using chipset-specific cache
* flushing at bind time. A better name might be DRM_BO_FLAG_TT_UNSNOOPED,
* as the eviction to local memory (TTM unbind) on map is just a side effect
* to prevent aggressive cache prefetch from the GPU disturbing the cache
* management that the DRM is doing.
*
* Flags: Acknowledge.
* Buffers allocated with this flag should not be used for suballocators
* This type may have issues on CPUs with over-aggressive caching