2 * Copyright (C) 2011-2013 Matteo Landi, Luigi Rizzo. All rights reserved.
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36 * Definitions of constants and the structures used by the netmap
37 * framework, for the part visible to both kernel and userspace.
38 * Detailed info on netmap is available with "man netmap" or at
40 * http://info.iet.unipi.it/~luigi/netmap/
42 * This API is also used to communicate with the VALE software switch
45 #ifndef _NET_NETMAP_H_
46 #define _NET_NETMAP_H_
49 * --- Netmap data structures ---
51 * The userspace data structures used by netmap are shown below.
52 * They are allocated by the kernel and mmap()ed by userspace threads.
53 * Pointers are implemented as memory offsets or indexes,
54 * so that they can be easily dereferenced in kernel and userspace.
56 KERNEL (opaque, obviously)
58 ====================================================================
60 USERSPACE | struct netmap_ring
61 +---->+--------------+
63 struct netmap_if (nifp, 1 per fd) / | avail |
64 +---------------+ / | buf_ofs |
65 | ni_tx_rings | / +==============+
66 | ni_rx_rings | / | buf_idx, len | slot[0]
68 | | / +--------------+
69 +===============+ / | buf_idx, len | slot[1]
70 | txring_ofs[0] | (rel.to nifp)--' | flags, ptr |
71 | txring_ofs[1] | +--------------+
72 (ni_tx_rings+1 entries) (num_slots entries)
73 | txring_ofs[t] | | buf_idx, len | slot[n-1]
74 +---------------+ | flags, ptr |
75 | rxring_ofs[0] | +--------------+
77 (ni_rx_rings+1 entries)
81 * For each "interface" (NIC, host stack, VALE switch port) attached to a
82 * file descriptor, the mmap()ed region contains a (logically readonly)
83 * struct netmap_if pointing to struct netmap_ring's.
84 * There is one netmap_ring per physical NIC ring, plus one tx/rx ring
85 * pair attached to the host stack (this pair is unused for VALE ports).
87 * All physical/host stack ports share the same memory region,
88 * so that zero-copy can be implemented between them.
89 * VALE switch ports instead have separate memory regions.
91 * The netmap_ring is the userspace-visible replica of the NIC ring.
92 * Each slot has the index of a buffer (MTU-sized and residing in the
93 * mmapped region), its length and some flags. An extra 64-bit pointer
94 * is provided for user-supplied buffers in the tx path.
96 * In user space, the buffer address is computed as
97 * (char *)ring + buf_ofs + index*NETMAP_BUF_SIZE
101 * struct netmap_slot is a buffer descriptor
103 * buf_idx the index of the buffer associated to the slot.
104 * len the length of the payload
105 * flags control operation on the slot, as defined below
107 * NS_BUF_CHANGED must be set whenever userspace wants
108 * to change buf_idx (it might be necessary to
111 * NS_REPORT must be set if we want the NIC to generate an interrupt
112 * when this slot is used. Leaving it to 0 improves
115 * NS_FORWARD if set on a receive ring, and the device is in
116 * transparent mode, buffers released with the flag set
117 * will be forwarded to the 'other' side (host stack
118 * or NIC, respectively) on the next select() or ioctl()
120 * NS_NO_LEARN on a VALE switch, do not 'learn' the source port for
123 * NS_INDIRECT (tx rings only) data is in a userspace buffer pointed
124 * by the ptr field in the slot.
126 * NS_MOREFRAG Part of a multi-segment frame. The last (or only)
127 * segment must not have this flag.
128 * Only supported on VALE ports.
130 * NS_PORT_MASK the high 8 bits of the flag, if not zero, indicate the
131 * destination port for the VALE switch, overriding
136 uint32_t buf_idx; /* buffer index */
137 uint16_t len; /* packet length */
138 uint16_t flags; /* buf changed, etc. */
139 #define NS_BUF_CHANGED 0x0001 /* buf_idx changed */
140 #define NS_REPORT 0x0002 /* ask the hardware to report results
141 * e.g. by generating an interrupt
143 #define NS_FORWARD 0x0004 /* pass packet to the other endpoint
144 * (host stack or device)
146 #define NS_NO_LEARN 0x0008
147 #define NS_INDIRECT 0x0010
148 #define NS_MOREFRAG 0x0020
149 #define NS_PORT_SHIFT 8
150 #define NS_PORT_MASK (0xff << NS_PORT_SHIFT)
152 * in rx rings, the high 8 bits
153 * are the number of fragments.
155 #define NS_RFRAGS(_slot) ( ((_slot)->flags >> 8) & 0xff)
156 uint64_t ptr; /* pointer for indirect buffers */
162 * Netmap representation of a TX or RX ring (also known as "queue").
163 * This is a queue implemented as a fixed-size circular array.
164 * At the software level, two fields are important: avail and cur.
168 * avail tells how many slots are available for transmission.
169 * It is updated by the kernel in each netmap system call.
170 * It MUST BE decremented by the user when it
171 * adds a new packet to send.
173 * cur indicates the slot to use for the next packet
174 * to send (i.e. the "tail" of the queue).
175 * It MUST BE incremented by the user before
176 * netmap system calls to reflect the number of newly
178 * It is checked by the kernel on netmap system calls
179 * (normally unmodified by the kernel unless invalid).
183 * avail is the number of packets available (possibly 0).
184 * It is updated by the kernel in each netmap system call.
185 * It MUST BE decremented by the user when it
188 * cur indicates the first slot that contains a packet not
189 * yet processed (the "head" of the queue).
190 * It MUST BE incremented by the user when it consumes
193 * reserved indicates the number of buffers before 'cur'
194 * that the user has not released yet. Normally 0,
195 * it MUST BE incremented by the user when it
196 * does not return the buffer immediately, and decremented
197 * when the buffer is finally freed.
200 * DATA OWNERSHIP/LOCKING:
201 * The netmap_ring, all slots, and buffers in the range
202 * [reserved-cur , cur+avail[ are owned by the user program,
203 * and the kernel only touches them in the same thread context
204 * during a system call.
205 * Other buffers are reserved for use by the NIC's DMA engines.
208 * NR_TIMESTAMP updates the 'ts' field on each syscall. This is
209 * a global timestamp for all packets.
210 * NR_RX_TSTMP if set, the last 64 byte in each buffer will
211 * contain a timestamp for the frame supplied by
212 * the hardware (if supported)
213 * NR_FORWARD if set, the NS_FORWARD flag in each slot of the
214 * RX ring is checked, and if set the packet is
215 * passed to the other side (host stack or device,
216 * respectively). This permits bpf-like behaviour
217 * or transparency for selected packets.
221 * buf_ofs is meant to be used through macros.
222 * It contains the offset of the buffer region from this
225 const ssize_t buf_ofs;
226 const uint32_t num_slots; /* number of slots in the ring. */
227 uint32_t avail; /* number of usable slots */
228 uint32_t cur; /* 'current' r/w position */
229 uint32_t reserved; /* not refilled before current */
231 const uint16_t nr_buf_size;
233 #define NR_TIMESTAMP 0x0002 /* set timestamp on *sync() */
234 #define NR_FORWARD 0x0004 /* enable NS_FORWARD for ring */
235 #define NR_RX_TSTMP 0x0008 /* set rx timestamp in slots */
237 struct timeval ts; /* time of last *sync() */
239 /* the slots follow. This struct has variable size */
240 struct netmap_slot slot[0]; /* array of slots. */
245 * Netmap representation of an interface and its queue(s).
246 * This is initialized by the kernel when binding a file
247 * descriptor to a port, and should be considered as readonly
248 * by user programs. The kernel never uses it.
250 * There is one netmap_if for each file descriptor on which we want
252 * select/poll operates on one or all pairs depending on the value of
253 * nmr_queueid passed on the ioctl.
256 char ni_name[IFNAMSIZ]; /* name of the interface. */
257 const uint32_t ni_version; /* API version, currently unused */
258 const uint32_t ni_flags; /* properties */
259 #define NI_PRIV_MEM 0x1 /* private memory region */
261 const uint32_t ni_rx_rings; /* number of rx rings */
262 const uint32_t ni_tx_rings; /* number of tx rings */
264 * The following array contains the offset of each netmap ring
265 * from this structure. The first ni_tx_rings+1 entries refer
266 * to the tx rings, the next ni_rx_rings+1 refer to the rx rings
267 * (the last entry in each block refers to the host stack rings).
268 * The area is filled up by the kernel on NIOCREGIF,
269 * and then only read by userspace code.
271 const ssize_t ring_ofs[0];
276 * ioctl names and related fields
278 * NIOCGINFO takes a struct ifreq, the interface name is the input,
279 * the outputs are number of queues and number of descriptor
280 * for each queue (useful to set number of threads etc.).
281 * The info returned is only advisory and may change before
282 * the interface is bound to a file descriptor.
284 * NIOCREGIF takes an interface name within a struct ifreq,
285 * and activates netmap mode on the interface (if possible).
287 * nr_name is the name of the interface
289 * nr_tx_slots, nr_tx_slots, nr_tx_rings, nr_rx_rings
290 * indicate the configuration of the port on return.
292 * On input, non-zero values for nr_tx_rings, nr_tx_slots and the
293 * rx counterparts may be used to reconfigure the port according
294 * to the requested values, but this is not guaranteed.
295 * The actual values are returned on completion of the ioctl().
298 * indicates how rings should be bound to the file descriptors.
299 * The default (0) means all physical rings of a NIC are bound.
300 * NETMAP_HW_RING plus a ring number lets you bind just
301 * a single ring pair.
302 * NETMAP_SW_RING binds only the host tx/rx rings
303 * NETMAP_NO_TX_POLL prevents select()/poll() from pushing
304 * out packets on the tx ring unless POLLOUT is specified.
306 * NETMAP_PRIV_MEM is a return value used to indicate that
307 * this ring is in a private memory region hence buffer
308 * swapping cannot be used
310 * nr_cmd is used to configure NICs attached to a VALE switch,
311 * or to dump the configuration of a VALE switch.
313 * nr_cmd = NETMAP_BDG_ATTACH and nr_name = vale*:ifname
314 * attaches the NIC to the switch, with nr_ringid specifying
317 * nr_cmd = NETMAP_BDG_DETACH and nr_name = vale*:ifname
318 * disconnects a previously attached NIC
320 * nr_cmd = NETMAP_BDG_LIST is used to list the configuration
321 * of VALE switches, with additional arguments.
323 * NIOCTXSYNC, NIOCRXSYNC synchronize tx or rx queues,
324 * whose identity is set in NIOCREGIF through nr_ringid
326 * NETMAP_API is the API version.
330 * struct nmreq overlays a struct ifreq
333 char nr_name[IFNAMSIZ];
334 uint32_t nr_version; /* API version */
335 #define NETMAP_API 5 /* current version */
336 uint32_t nr_offset; /* nifp offset in the shared region */
337 uint32_t nr_memsize; /* size of the shared region */
338 uint32_t nr_tx_slots; /* slots in tx rings */
339 uint32_t nr_rx_slots; /* slots in rx rings */
340 uint16_t nr_tx_rings; /* number of tx rings */
341 uint16_t nr_rx_rings; /* number of rx rings */
342 uint16_t nr_ringid; /* ring(s) we care about */
343 #define NETMAP_PRIV_MEM 0x8000 /* rings use private memory */
344 #define NETMAP_HW_RING 0x4000 /* low bits indicate one hw ring */
345 #define NETMAP_SW_RING 0x2000 /* process the sw ring */
346 #define NETMAP_NO_TX_POLL 0x1000 /* no automatic txsync on poll */
347 #define NETMAP_RING_MASK 0xfff /* the ring number */
349 #define NETMAP_BDG_ATTACH 1 /* attach the NIC */
350 #define NETMAP_BDG_DETACH 2 /* detach the NIC */
351 #define NETMAP_BDG_LOOKUP_REG 3 /* register lookup function */
352 #define NETMAP_BDG_LIST 4 /* get bridge's info */
354 #define NETMAP_BDG_HOST 1 /* attach the host stack on ATTACH */
360 * FreeBSD uses the size value embedded in the _IOWR to determine
361 * how much to copy in/out. So we need it to match the actual
362 * data structure we pass. We put some spares in the structure
363 * to ease compatibility with other versions
365 #define NIOCGINFO _IOWR('i', 145, struct nmreq) /* return IF info */
366 #define NIOCREGIF _IOWR('i', 146, struct nmreq) /* interface register */
367 #define NIOCUNREGIF _IO('i', 147) /* deprecated. Was interface unregister */
368 #define NIOCTXSYNC _IO('i', 148) /* sync tx queues */
369 #define NIOCRXSYNC _IO('i', 149) /* sync rx queues */
370 #endif /* !NIOCREGIF */
372 #endif /* _NET_NETMAP_H_ */