A bit more background about this: this flag allows to get discard from
the app down to the kernel, where most memory managers are able to do
discard while mapping level without the whole map-non-block +
create/destroy resource roundtrip. This is Keith's idea.
Jose
On Fri, 2011-02-18 at 08:15 -0800, jfons...@vmware.com wrote:
> From: Keith Whitwell <kei...@vmware.com>
>
> ---
> src/gallium/include/pipe/p_defines.h | 19 +++++++++++++++++--
> 1 files changed, 17 insertions(+), 2 deletions(-)
>
> diff --git a/src/gallium/include/pipe/p_defines.h
> b/src/gallium/include/pipe/p_defines.h
> index f66bbaf..2de707f 100644
> --- a/src/gallium/include/pipe/p_defines.h
> +++ b/src/gallium/include/pipe/p_defines.h
> @@ -229,9 +229,9 @@ enum pipe_transfer_usage {
> *
> * See also:
> * - OpenGL's ARB_map_buffer_range extension, MAP_INVALIDATE_RANGE_BIT
> flag.
> - * - Direct3D's D3DLOCK_DISCARD flag.
> */
> PIPE_TRANSFER_DISCARD = (1 << 8),
> + PIPE_TRANSFER_DISCARD_RANGE = (1 << 8),
>
> /**
> * Fail if the resource cannot be mapped immediately.
> @@ -266,7 +266,22 @@ enum pipe_transfer_usage {
> * - pipe_context::transfer_flush_region
> * - OpenGL's ARB_map_buffer_range extension, MAP_FLUSH_EXPLICIT_BIT flag.
> */
> - PIPE_TRANSFER_FLUSH_EXPLICIT = (1 << 11)
> + PIPE_TRANSFER_FLUSH_EXPLICIT = (1 << 11),
> +
> + /**
> + * Discards all memory backing the resource.
> + *
> + * It should not be used with PIPE_TRANSFER_CPU_READ.
> + *
> + * This is equivalent to:
> + * - OpenGL's ARB_map_buffer_range extension, MAP_INVALIDATE_BUFFER_BIT
> + * - BufferData(NULL) on a GL buffer
> + * - Direct3D's D3DLOCK_DISCARD flag.
> + * - WDDM's D3DDDICB_LOCKFLAGS.Discard flag.
> + * - D3D10 DDI's D3D10_DDI_MAP_WRITE_DISCARD flag
> + * - D3D10's D3D10_MAP_WRITE_DISCARD flag.
> + */
> + PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE = (1 << 12)
>
> };
>
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