2 * Copyright (C) 2011 Matteo Landi, Luigi Rizzo. All rights reserved.
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5 * modification, are permitted provided that the following conditions are
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18 * software without specific prior written permission.
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35 * $Id: netmap.h 9753 2011-11-28 15:10:43Z luigi $
37 * This header contains the definitions of the constants and the
38 * structures needed by the ``netmap'' module, both kernel and
42 #ifndef _NET_NETMAP_H_
43 #define _NET_NETMAP_H_
46 * --- Netmap data structures ---
48 * The data structures used by netmap are shown below. Those in
49 * capital letters are in an mmapp()ed area shared with userspace,
50 * while others are private to the kernel.
51 * Shared structures do not contain pointers but only relative
52 * offsets, so that addressing is portable between kernel and userspace.
54 * The 'softc' of each interface is extended with a struct netmap_adapter
55 * containing information to support netmap operation. In addition to
56 * the fixed fields, it has two pointers to reach the arrays of
57 * 'struct netmap_kring' which in turn reaches the various
58 * struct netmap_ring, shared with userspace.
64 | if_pspare[0] ----------+
67 +----------------+<------+
70 | tx_rings *--------------------------------->+-------------+
71 | | netmap_kring | ring *---------> ...
72 | rx_rings *---------->+--------------+ | nr_hwcur |
73 +----------------+ | ring *-------+ | nr_hwavail |
74 | nr_hwcur | | | selinfo |
75 | nr_hwavail | | +-------------+
77 +--------------+ | (na_num_rings+1 entries)
79 (na_num_rings+1 entries) +-------------+
85 NETMAP_IF (nifp, one per file desc.) / | avail |
86 +---------------+ / | buf_ofs |
87 | ni_num_queues | / +=============+
88 | | / | buf_idx | slot[0]
91 +===============+ / | buf_idx | slot[1]
92 | txring_ofs[0] | (rel.to nifp)--' | len, flags |
93 | txring_ofs[1] | +-------------+
94 (num_rings+1 entries) (nr_num_slots entries)
95 | txring_ofs[n] | | buf_idx | slot[n-1]
96 +---------------+ | len, flags |
97 | rxring_ofs[0] | +-------------+
103 * The NETMAP_RING is the shadow ring that mirrors the NIC rings.
104 * Each slot has the index of a buffer, its length and some flags.
105 * In user space, the buffer address is computed as
106 * (char *)ring + buf_ofs + index*MAX_BUF_SIZE
107 * In the kernel, buffers do not necessarily need to be contiguous,
108 * and the virtual and physical addresses are derived through
109 * a lookup table. When userspace wants to use a different buffer
110 * in a location, it must set the NS_BUF_CHANGED flag to make
111 * sure that the kernel recomputes updates the hardware ring and
112 * other fields (bus_dmamap, etc.) as needed.
114 * Normally the driver is not requested to report the result of
115 * transmissions (this can dramatically speed up operation).
116 * However the user may request to report completion by setting
120 uint32_t buf_idx; /* buffer index */
121 uint16_t len; /* packet length, to be copied to/from the hw ring */
122 uint16_t flags; /* buf changed, etc. */
123 #define NS_BUF_CHANGED 0x0001 /* must resync the map, buffer changed */
124 #define NS_REPORT 0x0002 /* ask the hardware to report results
125 * e.g. by generating an interrupt
130 * Netmap representation of a TX or RX ring (also known as "queue").
131 * This is a queue implemented as a fixed-size circular array.
132 * At the software level, two fields are important: avail and cur.
135 * avail indicates the number of slots available for transmission.
136 * It is decremented by the application when it appends a
137 * packet, and set to nr_hwavail (see below) on a
138 * NIOCTXSYNC to reflect the actual state of the queue
139 * (keeping track of completed transmissions).
140 * cur indicates the empty slot to use for the next packet
141 * to send (i.e. the "tail" of the queue).
142 * It is incremented by the application.
144 * The kernel side of netmap uses two additional fields in its own
145 * private ring structure, netmap_kring:
146 * nr_hwcur is a copy of nr_cur on an NIOCTXSYNC.
147 * nr_hwavail is the number of slots known as available by the
148 * hardware. It is updated on an INTR (inc by the
149 * number of packets sent) and on a NIOCTXSYNC
150 * (decrease by nr_cur - nr_hwcur)
151 * A special case, nr_hwavail is -1 if the transmit
152 * side is idle (no pending transmits).
155 * avail is the number of packets available (possibly 0).
156 * It is decremented by the software when it consumes
157 * a packet, and set to nr_hwavail on a NIOCRXSYNC
158 * cur indicates the first slot that contains a packet
159 * (the "head" of the queue).
160 * It is incremented by the software when it consumes
163 * The kernel side of netmap uses two additional fields in the kring:
164 * nr_hwcur is a copy of nr_cur on an NIOCRXSYNC
165 * nr_hwavail is the number of packets available. It is updated
166 * on INTR (inc by the number of new packets arrived)
167 * and on NIOCRXSYNC (decreased by nr_cur - nr_hwcur).
169 * DATA OWNERSHIP/LOCKING:
170 * The netmap_ring is owned by the user program and it is only
171 * accessed or modified in the upper half of the kernel during
174 * The netmap_kring is only modified by the upper half of the kernel.
178 * nr_buf_base_ofs is meant to be used through macros.
179 * It contains the offset of the buffer region from this
182 const ssize_t buf_ofs;
183 const uint32_t num_slots; /* number of slots in the ring. */
184 uint32_t avail; /* number of usable slots */
185 uint32_t cur; /* 'current' r/w position */
187 const uint16_t nr_buf_size;
189 #define NR_TIMESTAMP 0x0002 /* set timestamp on *sync() */
191 struct timeval ts; /* time of last *sync() */
193 /* the slots follow. This struct has variable size */
194 struct netmap_slot slot[0]; /* array of slots. */
199 * Netmap representation of an interface and its queue(s).
200 * There is one netmap_if for each file descriptor on which we want
201 * to select/poll. We assume that on each interface has the same number
202 * of receive and transmit queues.
203 * select/poll operates on one or all pairs depending on the value of
204 * nmr_queueid passed on the ioctl.
207 char ni_name[IFNAMSIZ]; /* name of the interface. */
208 const u_int ni_version; /* API version, currently unused */
209 const u_int ni_num_queues; /* number of queue pairs (TX/RX). */
210 const u_int ni_rx_queues; /* if zero, use ni_num_queues */
212 * the following array contains the offset of the
213 * each netmap ring from this structure. The first num_queues+1
214 * refer to the tx rings, the next n+1 refer to the rx rings.
215 * The area is filled up by the kernel on NIOCREG,
216 * and then only read by userspace code.
217 * entries 0..ni_num_queues-1 indicate the hardware queues,
218 * entry ni_num_queues is the queue from/to the stack.
220 const ssize_t ring_ofs[0];
223 #ifndef IFCAP_NETMAP /* this should go in net/if.h */
224 #define IFCAP_NETMAP 0x100000
229 * ioctl names and related fields
231 * NIOCGINFO takes a struct ifreq, the interface name is the input,
232 * the outputs are number of queues and number of descriptor
233 * for each queue (useful to set number of threads etc.).
235 * NIOCREGIF takes an interface name within a struct ifreq,
236 * and activates netmap mode on the interface (if possible).
238 * NIOCUNREGIF unregisters the interface associated to the fd.
240 * NIOCTXSYNC, NIOCRXSYNC synchronize tx or rx queues,
241 * whose identity is set in NIOCREGIF through nr_ringid
245 * struct nmreq overlays a struct ifreq
248 char nr_name[IFNAMSIZ];
249 uint32_t nr_version; /* API version (unused) */
250 uint32_t nr_offset; /* nifp offset in the shared region */
251 uint32_t nr_memsize; /* size of the shared region */
252 uint32_t nr_numslots; /* descriptors per queue */
253 uint16_t nr_numrings;
254 uint16_t nr_ringid; /* ring(s) we care about */
255 #define NETMAP_HW_RING 0x4000 /* low bits indicate one hw ring */
256 #define NETMAP_SW_RING 0x2000 /* we process the sw ring */
257 #define NETMAP_NO_TX_POLL 0x1000 /* no gratuitous txsync on poll */
258 #define NETMAP_RING_MASK 0xfff /* the ring number */
261 #define NIOCGINFO _IOWR('i', 145, struct nmreq) /* return IF info */
262 #define NIOCREGIF _IOWR('i', 146, struct nmreq) /* interface register */
263 #define NIOCUNREGIF _IO('i', 147) /* interface unregister */
264 #define NIOCTXSYNC _IO('i', 148) /* sync tx queues */
265 #define NIOCRXSYNC _IO('i', 149) /* sync rx queues */
266 #endif /* !NIOCREGIF */
268 #endif /* _NET_NETMAP_H_ */