src/vlib/buffer.h - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2015 Cisco and/or its affiliates.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 /*
  * buffer.h: VLIB buffers
  *
  * Copyright (c) 2008 Eliot Dresselhaus
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sublicense, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice shall be
  * included in all copies or substantial portions of the Software.
  *
  *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */

 #ifndef included_vlib_buffer_h
 #define included_vlib_buffer_h

 #include <vppinfra/types.h>
 #include <vppinfra/cache.h>
 #include <vppinfra/serialize.h>
 #include <vppinfra/vector.h>
 #include <vppinfra/lock.h>
 #include <vlib/error.h>		/* for vlib_error_t */

 #include <vlib/config.h>	/* for __PRE_DATA_SIZE */
 #define VLIB_BUFFER_DATA_SIZE		(2048)
 #define VLIB_BUFFER_PRE_DATA_SIZE	__PRE_DATA_SIZE

 /** \file
     vlib buffer structure definition and a few select
     access methods. This structure and the buffer allocation
     mechanism should perhaps live in vnet, but it would take a lot
     of typing to make it so.
 */

 /* VLIB buffer representation. */
 typedef struct
 {
   CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
   STRUCT_MARK (template_start);
   /* Offset within data[] that we are currently processing.
      If negative current header points into predata area. */
   i16 current_data;  /**< signed offset in data[], pre_data[]
                         that we are currently processing.
                         If negative current header points into predata area.
                      */
   u16 current_length;  /**< Nbytes between current data and
                           the end of this buffer.
                        */
   u32 flags; /**< 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_REPL_FAIL: packet replication failure
                 <br> VLIB_BUFFER_RECYCLE: as it says
                 <br> VLIB_BUFFER_FLOW_REPORT: buffer is a flow report,
                 <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
              */

 /* any change to the following line requres update of
  * vlib_buffer_get_free_list_index(...) and
  * vlib_buffer_set_free_list_index(...) functions */
 #define VLIB_BUFFER_FREE_LIST_INDEX_MASK ((1 << 5) - 1)

 #define VLIB_BUFFER_IS_TRACED (1 << 5)
 #define VLIB_BUFFER_LOG2_NEXT_PRESENT (6)
 #define VLIB_BUFFER_NEXT_PRESENT (1 << VLIB_BUFFER_LOG2_NEXT_PRESENT)
 #define VLIB_BUFFER_IS_RECYCLED (1 << 7)
 #define VLIB_BUFFER_TOTAL_LENGTH_VALID (1 << 8)
 #define VLIB_BUFFER_REPL_FAIL (1 << 9)
 #define VLIB_BUFFER_RECYCLE (1 << 10)
 #define VLIB_BUFFER_FLOW_REPORT (1 << 11)
 #define VLIB_BUFFER_EXT_HDR_VALID (1 << 12)

   /* User defined buffer flags. */
 #define LOG2_VLIB_BUFFER_FLAG_USER(n) (32 - (n))
 #define VLIB_BUFFER_FLAG_USER(n) (1 << LOG2_VLIB_BUFFER_FLAG_USER(n))

     STRUCT_MARK (template_end);

   u32 next_buffer;   /**< Next buffer for this linked-list of buffers.
                         Only valid if VLIB_BUFFER_NEXT_PRESENT flag is set.
                      */

   vlib_error_t error;	/**< Error code for buffers to be enqueued
                            to error handler.
                         */
   u32 current_config_index; /**< Used by feature subgraph arcs to
                                visit enabled feature nodes
                             */

   u8 feature_arc_index;	/**< Used to identify feature arcs by intermediate
                            feature node
                         */

   u8 n_add_refs; /**< Number of additional references to this buffer. */

   u8 buffer_pool_index;	/**< index of buffer pool this buffer belongs. */
   u8 dont_waste_me[1]; /**< Available space in the (precious)
                           first 32 octets of buffer metadata
                           Before allocating any of it, discussion required!
                        */

   u32 opaque[10]; /**< Opaque data used by sub-graphs for their own purposes.
                     See .../vnet/vnet/buffer.h
                  */
     CLIB_CACHE_LINE_ALIGN_MARK (cacheline1);

   u32 trace_index; /**< Specifies index into trace buffer
                       if VLIB_PACKET_IS_TRACED flag is set.
                    */
   u32 recycle_count; /**< Used by L2 path recycle code */

   u32 total_length_not_including_first_buffer;
   /**< Only valid for first buffer in chain. Current length plus
      total length given here give total number of bytes in buffer chain.
   */
   u32 align_pad; /**< available */
   u32 opaque2[12];  /**< More opaque data, see ../vnet/vnet/buffer.h */

   /***** end of second cache line */
     CLIB_CACHE_LINE_ALIGN_MARK (cacheline2);
   u8 pre_data[VLIB_BUFFER_PRE_DATA_SIZE];  /**< Space for inserting data
                                                before buffer start.
                                                Packet rewrite string will be
                                                rewritten backwards and may extend
                                                back before buffer->data[0].
                                                Must come directly before packet data.
                                             */

   u8 data[0]; /**< Packet data. Hardware DMA here */
 } vlib_buffer_t;		/* Must be a multiple of 64B. */

 #define VLIB_BUFFER_HDR_SIZE  (sizeof(vlib_buffer_t) - VLIB_BUFFER_PRE_DATA_SIZE)

 /** \brief Prefetch buffer metadata.
     The first 64 bytes of buffer contains most header information

     @param b - (vlib_buffer_t *) pointer to the buffer
     @param type - LOAD, STORE. In most cases, STORE is the right answer
 */

 #define vlib_prefetch_buffer_header(b,type) CLIB_PREFETCH (b, 64, type)

 always_inline vlib_buffer_t *
 vlib_buffer_next_contiguous (vlib_buffer_t * b, u32 buffer_bytes)
 {
   return (void *) (b + 1) + buffer_bytes;
 }

 always_inline void
 vlib_buffer_struct_is_sane (vlib_buffer_t * b)
 {
   ASSERT (sizeof (b[0]) % 64 == 0);

   /* Rewrite data must be before and contiguous with packet data. */
   ASSERT (b->pre_data + VLIB_BUFFER_PRE_DATA_SIZE == b->data);
 }

 /** \brief Get pointer to current data to process

     @param b - (vlib_buffer_t *) pointer to the buffer
     @return - (void *) (b->data + b->current_data)
 */

 always_inline void *
 vlib_buffer_get_current (vlib_buffer_t * b)
 {
   /* Check bounds. */
   ASSERT ((signed) b->current_data >= (signed) -VLIB_BUFFER_PRE_DATA_SIZE);
   return b->data + b->current_data;
 }

 /** \brief Advance current data pointer by the supplied (signed!) amount

     @param b - (vlib_buffer_t *) pointer to the buffer
     @param l - (word) signed increment
 */
 always_inline void
 vlib_buffer_advance (vlib_buffer_t * b, word l)
 {
   ASSERT (b->current_length >= l);
   b->current_data += l;
   b->current_length -= l;
 }

 /** \brief Check if there is enough space in buffer to advance

     @param b - (vlib_buffer_t *) pointer to the buffer
     @param l - (word) size to check
     @return - 0 if there is less space than 'l' in buffer
 */
 always_inline u8
 vlib_buffer_has_space (vlib_buffer_t * b, word l)
 {
   return b->current_length >= l;
 }

 /** \brief Reset current header & length to state they were in when
     packet was received.

     @param b - (vlib_buffer_t *) pointer to the buffer
 */

 always_inline void
 vlib_buffer_reset (vlib_buffer_t * b)
 {
   b->current_length += clib_max (b->current_data, 0);
   b->current_data = 0;
 }

 /** \brief Get pointer to buffer's opaque data array

     @param b - (vlib_buffer_t *) pointer to the buffer
     @return - (void *) b->opaque
 */
 always_inline void *
 vlib_get_buffer_opaque (vlib_buffer_t * b)
 {
   return (void *) b->opaque;
 }

 /** \brief Get pointer to buffer's opaque2 data array

     @param b - (vlib_buffer_t *) pointer to the buffer
     @return - (void *) b->opaque2
 */
 always_inline void *
 vlib_get_buffer_opaque2 (vlib_buffer_t * b)
 {
   return (void *) b->opaque2;
 }

 /** \brief Get pointer to the end of buffer's data
  * @param b     pointer to the buffer
  * @return      pointer to tail of packet's data
  */
 always_inline u8 *
 vlib_buffer_get_tail (vlib_buffer_t * b)
 {
   return b->data + b->current_data + b->current_length;
 }

 /** \brief Append uninitialized data to buffer
  * @param b     pointer to the buffer
  * @param size  number of uninitialized bytes
  * @return      pointer to beginning of uninitialized data
  */
 always_inline void *
 vlib_buffer_put_uninit (vlib_buffer_t * b, u8 size)
 {
   void *p = vlib_buffer_get_tail (b);
   /* XXX make sure there's enough space */
   b->current_length += size;
   return p;
 }

 /** \brief Prepend uninitialized data to buffer
  * @param b     pointer to the buffer
  * @param size  number of uninitialized bytes
  * @return      pointer to beginning of uninitialized data
  */
 always_inline void *
 vlib_buffer_push_uninit (vlib_buffer_t * b, u8 size)
 {
   ASSERT (b->current_data + VLIB_BUFFER_PRE_DATA_SIZE >= size);
   b->current_data -= size;
   b->current_length += size;

   return vlib_buffer_get_current (b);
 }

 /** \brief Make head room, typically for packet headers
  * @param b     pointer to the buffer
  * @param size  number of head room bytes
  * @return      pointer to start of buffer (current data)
  */
 always_inline void *
 vlib_buffer_make_headroom (vlib_buffer_t * b, u8 size)
 {
   ASSERT (b->current_data + VLIB_BUFFER_PRE_DATA_SIZE >= size);
   b->current_data += size;
   return vlib_buffer_get_current (b);
 }

 /** \brief Retrieve bytes from buffer head
  * @param b     pointer to the buffer
  * @param size  number of bytes to pull
  * @return      pointer to start of buffer (current data)
  */
 always_inline void *
 vlib_buffer_pull (vlib_buffer_t * b, u8 size)
 {
   if (b->current_length + VLIB_BUFFER_PRE_DATA_SIZE < size)
     return 0;

   void *data = vlib_buffer_get_current (b);
   vlib_buffer_advance (b, size);
   return data;
 }

 /* Forward declaration. */
 struct vlib_main_t;

 typedef struct vlib_buffer_free_list_t
 {
   /* Template buffer used to initialize first 16 bytes of buffers
      allocated on this free list. */
   vlib_buffer_t buffer_init_template;

   /* Our index into vlib_main_t's buffer_free_list_pool. */
   u32 index;

   /* Number of data bytes for buffers in this free list. */
   u32 n_data_bytes;

   /* Number of buffers to allocate when we need to allocate new buffers
      from physmem heap. */
   u32 min_n_buffers_each_physmem_alloc;

   /* Total number of buffers allocated from this free list. */
   u32 n_alloc;

   /* Vector of free buffers.  Each element is a byte offset into I/O heap. */
   u32 *buffers;

   /* global vector of free buffers, used only on main thread.
      Bufers are returned to global buffers only in case when number of
      buffers on free buffers list grows about threshold */
   u32 *global_buffers;
   clib_spinlock_t global_buffers_lock;

   /* Memory chunks allocated for this free list
      recorded here so they can be freed when free list
      is deleted. */
   void **buffer_memory_allocated;

   /* Free list name. */
   u8 *name;

   /* Callback functions to initialize newly allocated buffers.
      If null buffers are zeroed. */
   void (*buffer_init_function) (struct vlib_main_t * vm,
 				struct vlib_buffer_free_list_t * fl,
 				u32 * buffers, u32 n_buffers);

   /* Callback function to announce that buffers have been
      added to the freelist */
   void (*buffers_added_to_freelist_function)
     (struct vlib_main_t * vm, struct vlib_buffer_free_list_t * fl);

   uword buffer_init_function_opaque;
 } __attribute__ ((aligned (16))) vlib_buffer_free_list_t;

 typedef uword (vlib_buffer_fill_free_list_cb_t) (struct vlib_main_t * vm,
 						 vlib_buffer_free_list_t * fl,
 						 uword min_free_buffers);
 typedef void (vlib_buffer_free_cb_t) (struct vlib_main_t * vm, u32 * buffers,
 				      u32 n_buffers);
 typedef void (vlib_buffer_free_no_next_cb_t) (struct vlib_main_t * vm,
 					      u32 * buffers, u32 n_buffers);

 typedef struct
 {
   vlib_buffer_fill_free_list_cb_t *vlib_buffer_fill_free_list_cb;
   vlib_buffer_free_cb_t *vlib_buffer_free_cb;
   vlib_buffer_free_no_next_cb_t *vlib_buffer_free_no_next_cb;
   void (*vlib_packet_template_init_cb) (struct vlib_main_t * vm, void *t,
 					void *packet_data,
 					uword n_packet_data_bytes,
 					uword
 					min_n_buffers_each_physmem_alloc,
 					u8 * name);
   void (*vlib_buffer_delete_free_list_cb) (struct vlib_main_t * vm,
 					   u32 free_list_index);
 } vlib_buffer_callbacks_t;

 extern vlib_buffer_callbacks_t *vlib_buffer_callbacks;

 typedef struct
 {
   CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
   uword start;
   uword size;
   vlib_physmem_region_index_t physmem_region;
 } vlib_buffer_pool_t;

 typedef struct
 {
   CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
   /* Virtual memory address and size of buffer memory, used for calculating
      buffer index */
   uword buffer_mem_start;
   uword buffer_mem_size;
   vlib_buffer_pool_t *buffer_pools;

   /* Buffer free callback, for subversive activities */
     u32 (*buffer_free_callback) (struct vlib_main_t * vm,
 				 u32 * buffers,
 				 u32 n_buffers, u32 follow_buffer_next);
   /* Pool of buffer free lists.
      Multiple free lists exist for packet generator which uses
      separate free lists for each packet stream --- so as to avoid
      initializing static data for each packet generated. */
   vlib_buffer_free_list_t *buffer_free_list_pool;
 #define VLIB_BUFFER_DEFAULT_FREE_LIST_INDEX (0)
 #define VLIB_BUFFER_DEFAULT_FREE_LIST_BYTES VLIB_BUFFER_DATA_SIZE

   /* Hash table mapping buffer size (rounded to next unit of
      sizeof (vlib_buffer_t)) to free list index. */
   uword *free_list_by_size;

   /* Hash table mapping buffer index into number
      0 => allocated but free, 1 => allocated and not-free.
      If buffer index is not in hash table then this buffer
      has never been allocated. */
   uword *buffer_known_hash;
   clib_spinlock_t buffer_known_hash_lockp;

   /* List of free-lists needing Blue Light Special announcements */
   vlib_buffer_free_list_t **announce_list;

   /* Callbacks */
   vlib_buffer_callbacks_t cb;
   int callbacks_registered;
 } vlib_buffer_main_t;

 u8 vlib_buffer_add_physmem_region (struct vlib_main_t *vm,
 				   vlib_physmem_region_index_t region);

 clib_error_t *vlib_buffer_main_init (struct vlib_main_t *vm);

 typedef struct
 {
   struct vlib_main_t *vlib_main;

   u32 first_buffer, last_buffer;

   union
   {
     struct
     {
       /* Total accumulated bytes in chain starting with first_buffer. */
       u32 n_total_data_bytes;

       /* Max number of bytes to accumulate in chain starting with first_buffer.
          As this limit is reached buffers are enqueued to next node. */
       u32 max_n_data_bytes_per_chain;

       /* Next node to enqueue buffers to relative to current process node. */
       u32 next_index;

       /* Free list to use to allocate new buffers. */
       u32 free_list_index;
     } tx;

     struct
     {
       /* CLIB fifo of buffer indices waiting to be unserialized. */
       u32 *buffer_fifo;

       /* Event type used to signal that RX buffers have been added to fifo. */
       uword ready_one_time_event;
     } rx;
   };
 } vlib_serialize_buffer_main_t;

 void serialize_open_vlib_buffer (serialize_main_t * m, struct vlib_main_t *vm,
 				 vlib_serialize_buffer_main_t * sm);
 void unserialize_open_vlib_buffer (serialize_main_t * m,
 				   struct vlib_main_t *vm,
 				   vlib_serialize_buffer_main_t * sm);

 u32 serialize_close_vlib_buffer (serialize_main_t * m);
 void unserialize_close_vlib_buffer (serialize_main_t * m);
 void *vlib_set_buffer_free_callback (struct vlib_main_t *vm, void *fp);

 always_inline u32
 serialize_vlib_buffer_n_bytes (serialize_main_t * m)
 {
   serialize_stream_t *s = &m->stream;
   vlib_serialize_buffer_main_t *sm
     = uword_to_pointer (m->stream.data_function_opaque,
 			vlib_serialize_buffer_main_t *);
   return sm->tx.n_total_data_bytes + s->current_buffer_index +
     vec_len (s->overflow_buffer);
 }

 /*
  */

 /** \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...
 */
 #define VLIB_BUFFER_TRACE_TRAJECTORY 0

 #if VLIB_BUFFER_TRACE_TRAJECTORY > 0
 extern void (*vlib_buffer_trace_trajectory_cb) (vlib_buffer_t * b, u32 index);
 extern void (*vlib_buffer_trace_trajectory_init_cb) (vlib_buffer_t * b);
 extern void vlib_buffer_trace_trajectory_init (vlib_buffer_t * b);
 #define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b) \
   vlib_buffer_trace_trajectory_init (b);
 #else
 #define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b)
 #endif /* VLIB_BUFFER_TRACE_TRAJECTORY */

 #endif /* included_vlib_buffer_h */

 #define VLIB_BUFFER_REGISTER_CALLBACKS(x,...)                           \
     __VA_ARGS__ vlib_buffer_callbacks_t __##x##_buffer_callbacks;       \
 static void __vlib_add_buffer_callbacks_t_##x (void)                    \
     __attribute__((__constructor__)) ;                                  \
 static void __vlib_add_buffer_callbacks_t_##x (void)                    \
 {                                                                       \
     if (vlib_buffer_callbacks)                                          \
       clib_panic ("vlib buffer callbacks already registered");          \
     vlib_buffer_callbacks = &__##x##_buffer_callbacks;                  \
 }                                                                       \
 __VA_ARGS__ vlib_buffer_callbacks_t __##x##_buffer_callbacks

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* Copyright (c) 2015 Cisco and/or its affiliates.
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at:
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	/*
	* buffer.h: VLIB buffers
	*
	* Copyright (c) 2008 Eliot Dresselhaus
	*
	* Permission is hereby granted, free of charge, to any person obtaining
	* a copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sublicense, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* The above copyright notice and this permission notice shall be
	* included in all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
	* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
	* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
	* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*/

	#ifndef included_vlib_buffer_h
	#define included_vlib_buffer_h

	#include <vppinfra/types.h>
	#include <vppinfra/cache.h>
	#include <vppinfra/serialize.h>
	#include <vppinfra/vector.h>
	#include <vppinfra/lock.h>
	#include <vlib/error.h> /* for vlib_error_t */

	#include <vlib/config.h> /* for __PRE_DATA_SIZE */
	#define VLIB_BUFFER_DATA_SIZE (2048)
	#define VLIB_BUFFER_PRE_DATA_SIZE __PRE_DATA_SIZE

	/** \file
	vlib buffer structure definition and a few select
	access methods. This structure and the buffer allocation
	mechanism should perhaps live in vnet, but it would take a lot
	of typing to make it so.
	*/

	/* VLIB buffer representation. */
	typedef struct
	{
	CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
	STRUCT_MARK (template_start);
	/* Offset within data[] that we are currently processing.
	If negative current header points into predata area. */
	i16 current_data; /**< signed offset in data[], pre_data[]
	that we are currently processing.
	If negative current header points into predata area.
	*/
	u16 current_length; /**< Nbytes between current data and
	the end of this buffer.
	*/
	u32 flags; /**< 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_REPL_FAIL: packet replication failure
	<br> VLIB_BUFFER_RECYCLE: as it says
	<br> VLIB_BUFFER_FLOW_REPORT: buffer is a flow report,
	<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
	*/

	/* any change to the following line requres update of
	* vlib_buffer_get_free_list_index(...) and
	* vlib_buffer_set_free_list_index(...) functions */
	#define VLIB_BUFFER_FREE_LIST_INDEX_MASK ((1 << 5) - 1)

	#define VLIB_BUFFER_IS_TRACED (1 << 5)
	#define VLIB_BUFFER_LOG2_NEXT_PRESENT (6)
	#define VLIB_BUFFER_NEXT_PRESENT (1 << VLIB_BUFFER_LOG2_NEXT_PRESENT)
	#define VLIB_BUFFER_IS_RECYCLED (1 << 7)
	#define VLIB_BUFFER_TOTAL_LENGTH_VALID (1 << 8)
	#define VLIB_BUFFER_REPL_FAIL (1 << 9)
	#define VLIB_BUFFER_RECYCLE (1 << 10)
	#define VLIB_BUFFER_FLOW_REPORT (1 << 11)
	#define VLIB_BUFFER_EXT_HDR_VALID (1 << 12)

	/* User defined buffer flags. */
	#define LOG2_VLIB_BUFFER_FLAG_USER(n) (32 - (n))
	#define VLIB_BUFFER_FLAG_USER(n) (1 << LOG2_VLIB_BUFFER_FLAG_USER(n))

	STRUCT_MARK (template_end);

	u32 next_buffer; /**< Next buffer for this linked-list of buffers.
	Only valid if VLIB_BUFFER_NEXT_PRESENT flag is set.
	*/

	vlib_error_t error; /**< Error code for buffers to be enqueued
	to error handler.
	*/
	u32 current_config_index; /**< Used by feature subgraph arcs to
	visit enabled feature nodes
	*/

	u8 feature_arc_index; /**< Used to identify feature arcs by intermediate
	feature node
	*/

	u8 n_add_refs; /*< Number of additional references to this buffer. /

	u8 buffer_pool_index; /*< index of buffer pool this buffer belongs. /
	u8 dont_waste_me[1]; /**< Available space in the (precious)
	first 32 octets of buffer metadata
	Before allocating any of it, discussion required!
	*/

	u32 opaque[10]; /**< Opaque data used by sub-graphs for their own purposes.
	See .../vnet/vnet/buffer.h
	*/
	CLIB_CACHE_LINE_ALIGN_MARK (cacheline1);

	u32 trace_index; /**< Specifies index into trace buffer
	if VLIB_PACKET_IS_TRACED flag is set.
	*/
	u32 recycle_count; /*< Used by L2 path recycle code /

	u32 total_length_not_including_first_buffer;
	/**< Only valid for first buffer in chain. Current length plus
	total length given here give total number of bytes in buffer chain.
	*/
	u32 align_pad; /*< available /
	u32 opaque2[12]; /*< More opaque data, see ../vnet/vnet/buffer.h /

	/***** end of second cache line */
	CLIB_CACHE_LINE_ALIGN_MARK (cacheline2);
	u8 pre_data[VLIB_BUFFER_PRE_DATA_SIZE]; /**< Space for inserting data
	before buffer start.
	Packet rewrite string will be
	rewritten backwards and may extend
	back before buffer->data[0].
	Must come directly before packet data.
	*/

	u8 data[0]; /*< Packet data. Hardware DMA here /
	} vlib_buffer_t; /* Must be a multiple of 64B. */

	#define VLIB_BUFFER_HDR_SIZE (sizeof(vlib_buffer_t) - VLIB_BUFFER_PRE_DATA_SIZE)

	/** \brief Prefetch buffer metadata.
	The first 64 bytes of buffer contains most header information

	@param b - (vlib_buffer_t *) pointer to the buffer
	@param type - LOAD, STORE. In most cases, STORE is the right answer
	*/

	#define vlib_prefetch_buffer_header(b,type) CLIB_PREFETCH (b, 64, type)

	always_inline vlib_buffer_t *
	vlib_buffer_next_contiguous (vlib_buffer_t * b, u32 buffer_bytes)
	{
	return (void *) (b + 1) + buffer_bytes;
	}

	always_inline void
	vlib_buffer_struct_is_sane (vlib_buffer_t * b)
	{
	ASSERT (sizeof (b[0]) % 64 == 0);

	/* Rewrite data must be before and contiguous with packet data. */
	ASSERT (b->pre_data + VLIB_BUFFER_PRE_DATA_SIZE == b->data);
	}

	/** \brief Get pointer to current data to process

	@param b - (vlib_buffer_t *) pointer to the buffer
	@return - (void *) (b->data + b->current_data)
	*/

	always_inline void *
	vlib_buffer_get_current (vlib_buffer_t * b)
	{
	/* Check bounds. */
	ASSERT ((signed) b->current_data >= (signed) -VLIB_BUFFER_PRE_DATA_SIZE);
	return b->data + b->current_data;
	}

	/** \brief Advance current data pointer by the supplied (signed!) amount

	@param b - (vlib_buffer_t *) pointer to the buffer
	@param l - (word) signed increment
	*/
	always_inline void
	vlib_buffer_advance (vlib_buffer_t * b, word l)
	{
	ASSERT (b->current_length >= l);
	b->current_data += l;
	b->current_length -= l;
	}

	/** \brief Check if there is enough space in buffer to advance

	@param b - (vlib_buffer_t *) pointer to the buffer
	@param l - (word) size to check
	@return - 0 if there is less space than 'l' in buffer
	*/
	always_inline u8
	vlib_buffer_has_space (vlib_buffer_t * b, word l)
	{
	return b->current_length >= l;
	}

	/** \brief Reset current header & length to state they were in when
	packet was received.

	@param b - (vlib_buffer_t *) pointer to the buffer
	*/

	always_inline void
	vlib_buffer_reset (vlib_buffer_t * b)
	{
	b->current_length += clib_max (b->current_data, 0);
	b->current_data = 0;
	}

	/** \brief Get pointer to buffer's opaque data array

	@param b - (vlib_buffer_t *) pointer to the buffer
	@return - (void *) b->opaque
	*/
	always_inline void *
	vlib_get_buffer_opaque (vlib_buffer_t * b)
	{
	return (void *) b->opaque;
	}

	/** \brief Get pointer to buffer's opaque2 data array

	@param b - (vlib_buffer_t *) pointer to the buffer
	@return - (void *) b->opaque2
	*/
	always_inline void *
	vlib_get_buffer_opaque2 (vlib_buffer_t * b)
	{
	return (void *) b->opaque2;
	}

	/** \brief Get pointer to the end of buffer's data
	* @param b pointer to the buffer
	* @return pointer to tail of packet's data
	*/
	always_inline u8 *
	vlib_buffer_get_tail (vlib_buffer_t * b)
	{
	return b->data + b->current_data + b->current_length;
	}

	/** \brief Append uninitialized data to buffer
	* @param b pointer to the buffer
	* @param size number of uninitialized bytes
	* @return pointer to beginning of uninitialized data
	*/
	always_inline void *
	vlib_buffer_put_uninit (vlib_buffer_t * b, u8 size)
	{
	void *p = vlib_buffer_get_tail (b);
	/* XXX make sure there's enough space */
	b->current_length += size;
	return p;
	}

	/** \brief Prepend uninitialized data to buffer
	* @param b pointer to the buffer
	* @param size number of uninitialized bytes
	* @return pointer to beginning of uninitialized data
	*/
	always_inline void *
	vlib_buffer_push_uninit (vlib_buffer_t * b, u8 size)
	{
	ASSERT (b->current_data + VLIB_BUFFER_PRE_DATA_SIZE >= size);
	b->current_data -= size;
	b->current_length += size;

	return vlib_buffer_get_current (b);
	}

	/** \brief Make head room, typically for packet headers
	* @param b pointer to the buffer
	* @param size number of head room bytes
	* @return pointer to start of buffer (current data)
	*/
	always_inline void *
	vlib_buffer_make_headroom (vlib_buffer_t * b, u8 size)
	{
	ASSERT (b->current_data + VLIB_BUFFER_PRE_DATA_SIZE >= size);
	b->current_data += size;
	return vlib_buffer_get_current (b);
	}

	/** \brief Retrieve bytes from buffer head
	* @param b pointer to the buffer
	* @param size number of bytes to pull
	* @return pointer to start of buffer (current data)
	*/
	always_inline void *
	vlib_buffer_pull (vlib_buffer_t * b, u8 size)
	{
	if (b->current_length + VLIB_BUFFER_PRE_DATA_SIZE < size)
	return 0;

	void *data = vlib_buffer_get_current (b);
	vlib_buffer_advance (b, size);
	return data;
	}

	/* Forward declaration. */
	struct vlib_main_t;

	typedef struct vlib_buffer_free_list_t
	{
	/* Template buffer used to initialize first 16 bytes of buffers
	allocated on this free list. */
	vlib_buffer_t buffer_init_template;

	/* Our index into vlib_main_t's buffer_free_list_pool. */
	u32 index;

	/* Number of data bytes for buffers in this free list. */
	u32 n_data_bytes;

	/* Number of buffers to allocate when we need to allocate new buffers
	from physmem heap. */
	u32 min_n_buffers_each_physmem_alloc;

	/* Total number of buffers allocated from this free list. */
	u32 n_alloc;

	/* Vector of free buffers. Each element is a byte offset into I/O heap. */
	u32 *buffers;

	/* global vector of free buffers, used only on main thread.
	Bufers are returned to global buffers only in case when number of
	buffers on free buffers list grows about threshold */
	u32 *global_buffers;
	clib_spinlock_t global_buffers_lock;

	/* Memory chunks allocated for this free list
	recorded here so they can be freed when free list
	is deleted. */
	void **buffer_memory_allocated;

	/* Free list name. */
	u8 *name;

	/* Callback functions to initialize newly allocated buffers.
	If null buffers are zeroed. */
	void (buffer_init_function) (struct vlib_main_t vm,
	struct vlib_buffer_free_list_t * fl,
	u32 * buffers, u32 n_buffers);

	/* Callback function to announce that buffers have been
	added to the freelist */
	void (*buffers_added_to_freelist_function)
	(struct vlib_main_t * vm, struct vlib_buffer_free_list_t * fl);

	uword buffer_init_function_opaque;
	} __attribute__ ((aligned (16))) vlib_buffer_free_list_t;

	typedef uword (vlib_buffer_fill_free_list_cb_t) (struct vlib_main_t * vm,
	vlib_buffer_free_list_t * fl,
	uword min_free_buffers);
	typedef void (vlib_buffer_free_cb_t) (struct vlib_main_t * vm, u32 * buffers,
	u32 n_buffers);
	typedef void (vlib_buffer_free_no_next_cb_t) (struct vlib_main_t * vm,
	u32 * buffers, u32 n_buffers);

	typedef struct
	{
	vlib_buffer_fill_free_list_cb_t *vlib_buffer_fill_free_list_cb;
	vlib_buffer_free_cb_t *vlib_buffer_free_cb;
	vlib_buffer_free_no_next_cb_t *vlib_buffer_free_no_next_cb;
	void (vlib_packet_template_init_cb) (struct vlib_main_t vm, void *t,
	void *packet_data,
	uword n_packet_data_bytes,
	uword
	min_n_buffers_each_physmem_alloc,
	u8 * name);
	void (vlib_buffer_delete_free_list_cb) (struct vlib_main_t vm,
	u32 free_list_index);
	} vlib_buffer_callbacks_t;

	extern vlib_buffer_callbacks_t *vlib_buffer_callbacks;

	typedef struct
	{
	CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
	uword start;
	uword size;
	vlib_physmem_region_index_t physmem_region;
	} vlib_buffer_pool_t;

	typedef struct
	{
	CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
	/* Virtual memory address and size of buffer memory, used for calculating
	buffer index */
	uword buffer_mem_start;
	uword buffer_mem_size;
	vlib_buffer_pool_t *buffer_pools;

	/* Buffer free callback, for subversive activities */
	u32 (buffer_free_callback) (struct vlib_main_t vm,
	u32 * buffers,
	u32 n_buffers, u32 follow_buffer_next);
	/* Pool of buffer free lists.
	Multiple free lists exist for packet generator which uses
	separate free lists for each packet stream --- so as to avoid
	initializing static data for each packet generated. */
	vlib_buffer_free_list_t *buffer_free_list_pool;
	#define VLIB_BUFFER_DEFAULT_FREE_LIST_INDEX (0)
	#define VLIB_BUFFER_DEFAULT_FREE_LIST_BYTES VLIB_BUFFER_DATA_SIZE

	/* Hash table mapping buffer size (rounded to next unit of
	sizeof (vlib_buffer_t)) to free list index. */
	uword *free_list_by_size;

	/* Hash table mapping buffer index into number
	0 => allocated but free, 1 => allocated and not-free.
	If buffer index is not in hash table then this buffer
	has never been allocated. */
	uword *buffer_known_hash;
	clib_spinlock_t buffer_known_hash_lockp;

	/* List of free-lists needing Blue Light Special announcements */
	vlib_buffer_free_list_t **announce_list;

	/* Callbacks */
	vlib_buffer_callbacks_t cb;
	int callbacks_registered;
	} vlib_buffer_main_t;

	u8 vlib_buffer_add_physmem_region (struct vlib_main_t *vm,
	vlib_physmem_region_index_t region);

	clib_error_t vlib_buffer_main_init (struct vlib_main_t vm);

	typedef struct
	{
	struct vlib_main_t *vlib_main;

	u32 first_buffer, last_buffer;

	union
	{
	struct
	{
	/* Total accumulated bytes in chain starting with first_buffer. */
	u32 n_total_data_bytes;

	/* Max number of bytes to accumulate in chain starting with first_buffer.
	As this limit is reached buffers are enqueued to next node. */
	u32 max_n_data_bytes_per_chain;

	/* Next node to enqueue buffers to relative to current process node. */
	u32 next_index;

	/* Free list to use to allocate new buffers. */
	u32 free_list_index;
	} tx;

	struct
	{
	/* CLIB fifo of buffer indices waiting to be unserialized. */
	u32 *buffer_fifo;

	/* Event type used to signal that RX buffers have been added to fifo. */
	uword ready_one_time_event;
	} rx;
	};
	} vlib_serialize_buffer_main_t;

	void serialize_open_vlib_buffer (serialize_main_t * m, struct vlib_main_t *vm,
	vlib_serialize_buffer_main_t * sm);
	void unserialize_open_vlib_buffer (serialize_main_t * m,
	struct vlib_main_t *vm,
	vlib_serialize_buffer_main_t * sm);

	u32 serialize_close_vlib_buffer (serialize_main_t * m);
	void unserialize_close_vlib_buffer (serialize_main_t * m);
	void vlib_set_buffer_free_callback (struct vlib_main_t vm, void *fp);

	always_inline u32
	serialize_vlib_buffer_n_bytes (serialize_main_t * m)
	{
	serialize_stream_t *s = &m->stream;
	vlib_serialize_buffer_main_t *sm
	= uword_to_pointer (m->stream.data_function_opaque,
	vlib_serialize_buffer_main_t *);
	return sm->tx.n_total_data_bytes + s->current_buffer_index +
	vec_len (s->overflow_buffer);
	}

	/*
	*/

	/** \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...
	*/
	#define VLIB_BUFFER_TRACE_TRAJECTORY 0

	#if VLIB_BUFFER_TRACE_TRAJECTORY > 0
	extern void (vlib_buffer_trace_trajectory_cb) (vlib_buffer_t b, u32 index);
	extern void (vlib_buffer_trace_trajectory_init_cb) (vlib_buffer_t b);
	extern void vlib_buffer_trace_trajectory_init (vlib_buffer_t * b);
	#define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b) \
	vlib_buffer_trace_trajectory_init (b);
	#else
	#define VLIB_BUFFER_TRACE_TRAJECTORY_INIT(b)
	#endif /* VLIB_BUFFER_TRACE_TRAJECTORY */

	#endif /* included_vlib_buffer_h */

	#define VLIB_BUFFER_REGISTER_CALLBACKS(x,...) \
	__VA_ARGS__ vlib_buffer_callbacks_t __##x##_buffer_callbacks; \
	static void __vlib_add_buffer_callbacks_t_##x (void) \
	__attribute__((__constructor__)) ; \
	static void __vlib_add_buffer_callbacks_t_##x (void) \
	{ \
	if (vlib_buffer_callbacks) \
	clib_panic ("vlib buffer callbacks already registered"); \
	vlib_buffer_callbacks = &__##x##_buffer_callbacks; \
	} \
	__VA_ARGS__ vlib_buffer_callbacks_t __##x##_buffer_callbacks

	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/