+ /**
+ * Map a subrange of the buffer data store into the client's address space.
+ *
+ * The returned pointer is always relative to buffer start, regardless of
+ * the specified range. This is different from the ARB_map_buffer_range
+ * semantics because we don't forbid multiple mappings of the same buffer
+ * (yet).
+ */
+ void *(*buffer_map_range)( struct pipe_screen *screen,
+ struct pipe_buffer *buf,
+ unsigned offset,
+ unsigned length,
+ unsigned usage);
+
+ /**
+ * Notify a range that was actually written into.
+ *
+ * Can only be used if the buffer was mapped with the
+ * PIPE_BUFFER_USAGE_CPU_WRITE and PIPE_BUFFER_USAGE_FLUSH_EXPLICIT flags
+ * set.
+ *
+ * The range is relative to the buffer start, regardless of the range
+ * specified to buffer_map_range. This is different from the
+ * ARB_map_buffer_range semantics because we don't forbid multiple mappings
+ * of the same buffer (yet).
+ *
+ */
+ void (*buffer_flush_mapped_range)( struct pipe_screen *screen,
+ struct pipe_buffer *buf,
+ unsigned offset,
+ unsigned length);