+#define VLIB_BUFFER_FLAGS_ALL (0x0f)
+
+/** \brief Compile time buffer trajectory tracing option
+ Turn this on if you run into "bad monkey" contexts,
+ and you want to know exactly which nodes they've visited...
+ See vlib/main.c...
+*/
+#ifndef VLIB_BUFFER_TRACE_TRAJECTORY
+#define VLIB_BUFFER_TRACE_TRAJECTORY 0
+#endif /* VLIB_BUFFER_TRACE_TRAJECTORY */
+
+/** VLIB buffer representation. */
+typedef union
+{
+ struct
+ {
+ CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
+
+ /** signed offset in data[], pre_data[] that we are currently
+ * processing. If negative current header points into predata area. */
+ i16 current_data;
+
+ /** Nbytes between current data and the end of this buffer. */
+ u16 current_length;
+
+ /** buffer flags:
+ <br> VLIB_BUFFER_FREE_LIST_INDEX_MASK: bits used to store free list index,
+ <br> VLIB_BUFFER_IS_TRACED: trace this buffer.
+ <br> VLIB_BUFFER_NEXT_PRESENT: this is a multi-chunk buffer.
+ <br> VLIB_BUFFER_TOTAL_LENGTH_VALID: as it says
+ <br> VLIB_BUFFER_EXT_HDR_VALID: buffer contains valid external buffer manager header,
+ set to avoid adding it to a flow report
+ <br> VLIB_BUFFER_FLAG_USER(n): user-defined bit N
+ */
+ u32 flags;
+
+ /** Generic flow identifier */
+ u32 flow_id;
+
+ /** Reference count for this buffer. */
+ volatile u8 ref_count;
+
+ /** index of buffer pool this buffer belongs. */
+ u8 buffer_pool_index;
+
+ /** Error code for buffers to be enqueued to error handler. */
+ vlib_error_t error;
+
+ /** Next buffer for this linked-list of buffers. Only valid if
+ * VLIB_BUFFER_NEXT_PRESENT flag is set. */
+ u32 next_buffer;
+
+ /** The following fields can be in a union because once a packet enters
+ * the punt path, it is no longer on a feature arc */
+ union
+ {
+ /** Used by feature subgraph arcs to visit enabled feature nodes */
+ u32 current_config_index;
+ /* the reason the packet once punted */
+ u32 punt_reason;
+ };
+
+ /** Opaque data used by sub-graphs for their own purposes. */
+ u32 opaque[10];
+
+ /** part of buffer metadata which is initialized on alloc ends here. */
+ STRUCT_MARK (template_end);
+
+ /** start of 2nd half (2nd cacheline on systems where cacheline size is 64) */
+ CLIB_ALIGN_MARK (second_half, 64);