MFC r324075 (by imp): Tweak performance of nda completions

[FreeBSD/FreeBSD.git] / sys / dev / netmap / netmap_kern.h

/*
 * Copyright (C) 2011-2014 Matteo Landi, Luigi Rizzo. All rights reserved.
 * Copyright (C) 2013-2014 Universita` di Pisa. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * $FreeBSD$
 *
 * The header contains the definitions of constants and function
 * prototypes used only in kernelspace.
 */

#ifndef _NET_NETMAP_KERN_H_
#define _NET_NETMAP_KERN_H_

#if defined(linux)

#if  defined(CONFIG_NETMAP_VALE)
#define WITH_VALE
#endif
#if defined(CONFIG_NETMAP_PIPE)
#define WITH_PIPES
#endif
#if defined(CONFIG_NETMAP_MONITOR)
#define WITH_MONITOR
#endif
#if defined(CONFIG_NETMAP_GENERIC)
#define WITH_GENERIC
#endif
#if defined(CONFIG_NETMAP_V1000)
#define WITH_V1000
#endif

#else /* not linux */

#define WITH_VALE       // comment out to disable VALE support
#define WITH_PIPES
#define WITH_MONITOR
#define WITH_GENERIC

#endif

#if defined(__FreeBSD__)

#define likely(x)       __builtin_expect((long)!!(x), 1L)
#define unlikely(x)     __builtin_expect((long)!!(x), 0L)

#define NM_LOCK_T       struct mtx      /* low level spinlock, used to protect queues */

#define NM_MTX_T        struct sx       /* OS-specific mutex (sleepable) */
#define NM_MTX_INIT(m)          sx_init(&(m), #m)
#define NM_MTX_DESTROY(m)       sx_destroy(&(m))
#define NM_MTX_LOCK(m)          sx_xlock(&(m))
#define NM_MTX_UNLOCK(m)        sx_xunlock(&(m))
#define NM_MTX_ASSERT(m)        sx_assert(&(m), SA_XLOCKED)

#define NM_SELINFO_T    struct nm_selinfo
#define MBUF_LEN(m)     ((m)->m_pkthdr.len)
#define MBUF_IFP(m)     ((m)->m_pkthdr.rcvif)
#define NM_SEND_UP(ifp, m)      ((NA(ifp))->if_input)(ifp, m)

#define NM_ATOMIC_T     volatile int    // XXX ?
/* atomic operations */
#include <machine/atomic.h>
#define NM_ATOMIC_TEST_AND_SET(p)       (!atomic_cmpset_acq_int((p), 0, 1))
#define NM_ATOMIC_CLEAR(p)              atomic_store_rel_int((p), 0)

#if __FreeBSD_version >= 1100030
#define WNA(_ifp)       (_ifp)->if_netmap
#else /* older FreeBSD */
#define WNA(_ifp)       (_ifp)->if_pspare[0]
#endif /* older FreeBSD */

#if __FreeBSD_version >= 1100005
struct netmap_adapter *netmap_getna(if_t ifp);
#endif

#if __FreeBSD_version >= 1100027
#define MBUF_REFCNT(m)          ((m)->m_ext.ext_count)
#define SET_MBUF_REFCNT(m, x)   (m)->m_ext.ext_count = x
#else
#define MBUF_REFCNT(m)          ((m)->m_ext.ref_cnt ? *((m)->m_ext.ref_cnt) : -1)
#define SET_MBUF_REFCNT(m, x)   *((m)->m_ext.ref_cnt) = x
#endif

MALLOC_DECLARE(M_NETMAP);

struct nm_selinfo {
        struct selinfo si;
        struct mtx m;
};

void freebsd_selwakeup(struct nm_selinfo *si, int pri);

// XXX linux struct, not used in FreeBSD
struct net_device_ops {
};
struct ethtool_ops {
};
struct hrtimer {
};
#define NM_BNS_GET(b)
#define NM_BNS_PUT(b)

#elif defined (linux)

#define NM_LOCK_T       safe_spinlock_t // see bsd_glue.h
#define NM_SELINFO_T    wait_queue_head_t
#define MBUF_LEN(m)     ((m)->len)
#define MBUF_IFP(m)     ((m)->dev)
#define NM_SEND_UP(ifp, m)  \
                        do { \
                            m->priority = NM_MAGIC_PRIORITY_RX; \
                            netif_rx(m); \
                        } while (0)

#define NM_ATOMIC_T     volatile long unsigned int

#define NM_MTX_T        struct mutex    /* OS-specific sleepable lock */
#define NM_MTX_INIT(m)  mutex_init(&(m))
#define NM_MTX_DESTROY(m)       do { (void)(m); } while (0)
#define NM_MTX_LOCK(m)          mutex_lock(&(m))
#define NM_MTX_UNLOCK(m)        mutex_unlock(&(m))
#define NM_MTX_ASSERT(m)        mutex_is_locked(&(m))

#ifndef DEV_NETMAP
#define DEV_NETMAP
#endif /* DEV_NETMAP */

#elif defined (__APPLE__)

#warning apple support is incomplete.
#define likely(x)       __builtin_expect(!!(x), 1)
#define unlikely(x)     __builtin_expect(!!(x), 0)
#define NM_LOCK_T       IOLock *
#define NM_SELINFO_T    struct selinfo
#define MBUF_LEN(m)     ((m)->m_pkthdr.len)
#define NM_SEND_UP(ifp, m)      ((ifp)->if_input)(ifp, m)

#else

#error unsupported platform

#endif /* end - platform-specific code */

#define NMG_LOCK_T              NM_MTX_T
#define NMG_LOCK_INIT()         NM_MTX_INIT(netmap_global_lock)
#define NMG_LOCK_DESTROY()      NM_MTX_DESTROY(netmap_global_lock)
#define NMG_LOCK()              NM_MTX_LOCK(netmap_global_lock)
#define NMG_UNLOCK()            NM_MTX_UNLOCK(netmap_global_lock)
#define NMG_LOCK_ASSERT()       NM_MTX_ASSERT(netmap_global_lock)

#define ND(format, ...)
#define D(format, ...)                                          \
        do {                                                    \
                struct timeval __xxts;                          \
                microtime(&__xxts);                             \
                printf("%03d.%06d [%4d] %-25s " format "\n",    \
                (int)__xxts.tv_sec % 1000, (int)__xxts.tv_usec, \
                __LINE__, __FUNCTION__, ##__VA_ARGS__);         \
        } while (0)

/* rate limited, lps indicates how many per second */
#define RD(lps, format, ...)                                    \
        do {                                                    \
                static int t0, __cnt;                           \
                if (t0 != time_second) {                        \
                        t0 = time_second;                       \
                        __cnt = 0;                              \
                }                                               \
                if (__cnt++ < lps)                              \
                        D(format, ##__VA_ARGS__);               \
        } while (0)

struct netmap_adapter;
struct nm_bdg_fwd;
struct nm_bridge;
struct netmap_priv_d;

const char *nm_dump_buf(char *p, int len, int lim, char *dst);

#include "netmap_mbq.h"

extern NMG_LOCK_T       netmap_global_lock;

enum txrx { NR_RX = 0, NR_TX = 1, NR_TXRX };

static __inline const char*
nm_txrx2str(enum txrx t)
{
        return (t== NR_RX ? "RX" : "TX");
}

static __inline enum txrx
nm_txrx_swap(enum txrx t)
{
        return (t== NR_RX ? NR_TX : NR_RX);
}

#define for_rx_tx(t)    for ((t) = 0; (t) < NR_TXRX; (t)++)


/*
 * private, kernel view of a ring. Keeps track of the status of
 * a ring across system calls.
 *
 *      nr_hwcur        index of the next buffer to refill.
 *                      It corresponds to ring->head
 *                      at the time the system call returns.
 *
 *      nr_hwtail       index of the first buffer owned by the kernel.
 *                      On RX, hwcur->hwtail are receive buffers
 *                      not yet released. hwcur is advanced following
 *                      ring->head, hwtail is advanced on incoming packets,
 *                      and a wakeup is generated when hwtail passes ring->cur
 *                          On TX, hwcur->rcur have been filled by the sender
 *                      but not sent yet to the NIC; rcur->hwtail are available
 *                      for new transmissions, and hwtail->hwcur-1 are pending
 *                      transmissions not yet acknowledged.
 *
 * The indexes in the NIC and netmap rings are offset by nkr_hwofs slots.
 * This is so that, on a reset, buffers owned by userspace are not
 * modified by the kernel. In particular:
 * RX rings: the next empty buffer (hwtail + hwofs) coincides with
 *      the next empty buffer as known by the hardware (next_to_check or so).
 * TX rings: hwcur + hwofs coincides with next_to_send
 *
 * For received packets, slot->flags is set to nkr_slot_flags
 * so we can provide a proper initial value (e.g. set NS_FORWARD
 * when operating in 'transparent' mode).
 *
 * The following fields are used to implement lock-free copy of packets
 * from input to output ports in VALE switch:
 *      nkr_hwlease     buffer after the last one being copied.
 *                      A writer in nm_bdg_flush reserves N buffers
 *                      from nr_hwlease, advances it, then does the
 *                      copy outside the lock.
 *                      In RX rings (used for VALE ports),
 *                      nkr_hwtail <= nkr_hwlease < nkr_hwcur+N-1
 *                      In TX rings (used for NIC or host stack ports)
 *                      nkr_hwcur <= nkr_hwlease < nkr_hwtail
 *      nkr_leases      array of nkr_num_slots where writers can report
 *                      completion of their block. NR_NOSLOT (~0) indicates
 *                      that the writer has not finished yet
 *      nkr_lease_idx   index of next free slot in nr_leases, to be assigned
 *
 * The kring is manipulated by txsync/rxsync and generic netmap function.
 *
 * Concurrent rxsync or txsync on the same ring are prevented through
 * by nm_kr_(try)lock() which in turn uses nr_busy. This is all we need
 * for NIC rings, and for TX rings attached to the host stack.
 *
 * RX rings attached to the host stack use an mbq (rx_queue) on both
 * rxsync_from_host() and netmap_transmit(). The mbq is protected
 * by its internal lock.
 *
 * RX rings attached to the VALE switch are accessed by both senders
 * and receiver. They are protected through the q_lock on the RX ring.
 */
struct netmap_kring {
        struct netmap_ring      *ring;

        uint32_t        nr_hwcur;
        uint32_t        nr_hwtail;

        /*
         * Copies of values in user rings, so we do not need to look
         * at the ring (which could be modified). These are set in the
         * *sync_prologue()/finalize() routines.
         */
        uint32_t        rhead;
        uint32_t        rcur;
        uint32_t        rtail;

        uint32_t        nr_kflags;      /* private driver flags */
#define NKR_PENDINTR    0x1             // Pending interrupt.
#define NKR_EXCLUSIVE   0x2             /* exclusive binding */
        uint32_t        nkr_num_slots;

        /*
         * On a NIC reset, the NIC ring indexes may be reset but the
         * indexes in the netmap rings remain the same. nkr_hwofs
         * keeps track of the offset between the two.
         */
        int32_t         nkr_hwofs;

        uint16_t        nkr_slot_flags; /* initial value for flags */

        /* last_reclaim is opaque marker to help reduce the frequency
         * of operations such as reclaiming tx buffers. A possible use
         * is set it to ticks and do the reclaim only once per tick.
         */
        uint64_t        last_reclaim;


        NM_SELINFO_T    si;             /* poll/select wait queue */
        NM_LOCK_T       q_lock;         /* protects kring and ring. */
        NM_ATOMIC_T     nr_busy;        /* prevent concurrent syscalls */

        struct netmap_adapter *na;

        /* The following fields are for VALE switch support */
        struct nm_bdg_fwd *nkr_ft;
        uint32_t        *nkr_leases;
#define NR_NOSLOT       ((uint32_t)~0)  /* used in nkr_*lease* */
        uint32_t        nkr_hwlease;
        uint32_t        nkr_lease_idx;

        /* while nkr_stopped is set, no new [tr]xsync operations can
         * be started on this kring.
         * This is used by netmap_disable_all_rings()
         * to find a synchronization point where critical data
         * structures pointed to by the kring can be added or removed
         */
        volatile int nkr_stopped;

        /* Support for adapters without native netmap support.
         * On tx rings we preallocate an array of tx buffers
         * (same size as the netmap ring), on rx rings we
         * store incoming mbufs in a queue that is drained by
         * a rxsync.
         */
        struct mbuf **tx_pool;
        // u_int nr_ntc;                /* Emulation of a next-to-clean RX ring pointer. */
        struct mbq rx_queue;            /* intercepted rx mbufs. */

        uint32_t        users;          /* existing bindings for this ring */

        uint32_t        ring_id;        /* debugging */
        enum txrx       tx;             /* kind of ring (tx or rx) */
        char name[64];                  /* diagnostic */

        /* [tx]sync callback for this kring.
         * The default nm_kring_create callback (netmap_krings_create)
         * sets the nm_sync callback of each hardware tx(rx) kring to
         * the corresponding nm_txsync(nm_rxsync) taken from the
         * netmap_adapter; moreover, it sets the sync callback
         * of the host tx(rx) ring to netmap_txsync_to_host
         * (netmap_rxsync_from_host).
         *
         * Overrides: the above configuration is not changed by
         * any of the nm_krings_create callbacks.
         */
        int (*nm_sync)(struct netmap_kring *kring, int flags);
        int (*nm_notify)(struct netmap_kring *kring, int flags);

#ifdef WITH_PIPES
        struct netmap_kring *pipe;      /* if this is a pipe ring,
                                         * pointer to the other end
                                         */
        struct netmap_ring *save_ring;  /* pointer to hidden rings
                                         * (see netmap_pipe.c for details)
                                         */
#endif /* WITH_PIPES */

#ifdef WITH_VALE
        int (*save_notify)(struct netmap_kring *kring, int flags);
#endif

#ifdef WITH_MONITOR
        /* array of krings that are monitoring this kring */
        struct netmap_kring **monitors;
        uint32_t max_monitors; /* current size of the monitors array */
        uint32_t n_monitors;    /* next unused entry in the monitor array */
        /*
         * Monitors work by intercepting the sync and notify callbacks of the
         * monitored krings. This is implemented by replacing the pointers
         * above and saving the previous ones in mon_* pointers below
         */
        int (*mon_sync)(struct netmap_kring *kring, int flags);
        int (*mon_notify)(struct netmap_kring *kring, int flags);

        uint32_t mon_tail;  /* last seen slot on rx */
        uint32_t mon_pos;   /* index of this ring in the monitored ring array */
#endif
} __attribute__((__aligned__(64)));


/* return the next index, with wraparound */
static inline uint32_t
nm_next(uint32_t i, uint32_t lim)
{
        return unlikely (i == lim) ? 0 : i + 1;
}


/* return the previous index, with wraparound */
static inline uint32_t
nm_prev(uint32_t i, uint32_t lim)
{
        return unlikely (i == 0) ? lim : i - 1;
}


/*
 *
 * Here is the layout for the Rx and Tx rings.

       RxRING                            TxRING

      +-----------------+            +-----------------+
      |                 |            |                 |
      |XXX free slot XXX|            |XXX free slot XXX|
      +-----------------+            +-----------------+
head->| owned by user   |<-hwcur     | not sent to nic |<-hwcur
      |                 |            | yet             |
      +-----------------+            |                 |
 cur->| available to    |            |                 |
      | user, not read  |            +-----------------+
      | yet             |       cur->| (being          |
      |                 |            |  prepared)      |
      |                 |            |                 |
      +-----------------+            +     ------      +
tail->|                 |<-hwtail    |                 |<-hwlease
      | (being          | ...        |                 | ...
      |  prepared)      | ...        |                 | ...
      +-----------------+ ...        |                 | ...
      |                 |<-hwlease   +-----------------+
      |                 |      tail->|                 |<-hwtail
      |                 |            |                 |
      |                 |            |                 |
      |                 |            |                 |
      +-----------------+            +-----------------+

 * The cur/tail (user view) and hwcur/hwtail (kernel view)
 * are used in the normal operation of the card.
 *
 * When a ring is the output of a switch port (Rx ring for
 * a VALE port, Tx ring for the host stack or NIC), slots
 * are reserved in blocks through 'hwlease' which points
 * to the next unused slot.
 * On an Rx ring, hwlease is always after hwtail,
 * and completions cause hwtail to advance.
 * On a Tx ring, hwlease is always between cur and hwtail,
 * and completions cause cur to advance.
 *
 * nm_kr_space() returns the maximum number of slots that
 * can be assigned.
 * nm_kr_lease() reserves the required number of buffers,
 *    advances nkr_hwlease and also returns an entry in
 *    a circular array where completions should be reported.
 */


struct netmap_lut {
        struct lut_entry *lut;
        uint32_t objtotal;      /* max buffer index */
        uint32_t objsize;       /* buffer size */
};

struct netmap_vp_adapter; // forward

/*
 * The "struct netmap_adapter" extends the "struct adapter"
 * (or equivalent) device descriptor.
 * It contains all base fields needed to support netmap operation.
 * There are in fact different types of netmap adapters
 * (native, generic, VALE switch...) so a netmap_adapter is
 * just the first field in the derived type.
 */
struct netmap_adapter {
        /*
         * On linux we do not have a good way to tell if an interface
         * is netmap-capable. So we always use the following trick:
         * NA(ifp) points here, and the first entry (which hopefully
         * always exists and is at least 32 bits) contains a magic
         * value which we can use to detect that the interface is good.
         */
        uint32_t magic;
        uint32_t na_flags;      /* enabled, and other flags */
#define NAF_SKIP_INTR   1       /* use the regular interrupt handler.
                                 * useful during initialization
                                 */
#define NAF_SW_ONLY     2       /* forward packets only to sw adapter */
#define NAF_BDG_MAYSLEEP 4      /* the bridge is allowed to sleep when
                                 * forwarding packets coming from this
                                 * interface
                                 */
#define NAF_MEM_OWNER   8       /* the adapter uses its own memory area
                                 * that cannot be changed
                                 */
#define NAF_NATIVE      16      /* the adapter is native.
                                 * Virtual ports (non persistent vale ports,
                                 * pipes, monitors...) should never use
                                 * this flag.
                                 */
#define NAF_NETMAP_ON   32      /* netmap is active (either native or
                                 * emulated). Where possible (e.g. FreeBSD)
                                 * IFCAP_NETMAP also mirrors this flag.
                                 */
#define NAF_HOST_RINGS  64      /* the adapter supports the host rings */
#define NAF_FORCE_NATIVE 128    /* the adapter is always NATIVE */
#define NAF_BUSY        (1U<<31) /* the adapter is used internally and
                                  * cannot be registered from userspace
                                  */
        int active_fds; /* number of user-space descriptors using this
                         interface, which is equal to the number of
                         struct netmap_if objs in the mapped region. */

        u_int num_rx_rings; /* number of adapter receive rings */
        u_int num_tx_rings; /* number of adapter transmit rings */

        u_int num_tx_desc;  /* number of descriptor in each queue */
        u_int num_rx_desc;

        /* tx_rings and rx_rings are private but allocated
         * as a contiguous chunk of memory. Each array has
         * N+1 entries, for the adapter queues and for the host queue.
         */
        struct netmap_kring *tx_rings; /* array of TX rings. */
        struct netmap_kring *rx_rings; /* array of RX rings. */

        void *tailroom;                /* space below the rings array */
                                       /* (used for leases) */


        NM_SELINFO_T si[NR_TXRX];       /* global wait queues */

        /* count users of the global wait queues */
        int si_users[NR_TXRX];

        void *pdev; /* used to store pci device */

        /* copy of if_qflush and if_transmit pointers, to intercept
         * packets from the network stack when netmap is active.
         */
        int     (*if_transmit)(struct ifnet *, struct mbuf *);

        /* copy of if_input for netmap_send_up() */
        void     (*if_input)(struct ifnet *, struct mbuf *);

        /* references to the ifnet and device routines, used by
         * the generic netmap functions.
         */
        struct ifnet *ifp; /* adapter is ifp->if_softc */

        /*---- callbacks for this netmap adapter -----*/
        /*
         * nm_dtor() is the cleanup routine called when destroying
         *      the adapter.
         *      Called with NMG_LOCK held.
         *
         * nm_register() is called on NIOCREGIF and close() to enter
         *      or exit netmap mode on the NIC
         *      Called with NNG_LOCK held.
         *
         * nm_txsync() pushes packets to the underlying hw/switch
         *
         * nm_rxsync() collects packets from the underlying hw/switch
         *
         * nm_config() returns configuration information from the OS
         *      Called with NMG_LOCK held.
         *
         * nm_krings_create() create and init the tx_rings and
         *      rx_rings arrays of kring structures. In particular,
         *      set the nm_sync callbacks for each ring.
         *      There is no need to also allocate the corresponding
         *      netmap_rings, since netmap_mem_rings_create() will always
         *      be called to provide the missing ones.
         *      Called with NNG_LOCK held.
         *
         * nm_krings_delete() cleanup and delete the tx_rings and rx_rings
         *      arrays
         *      Called with NMG_LOCK held.
         *
         * nm_notify() is used to act after data have become available
         *      (or the stopped state of the ring has changed)
         *      For hw devices this is typically a selwakeup(),
         *      but for NIC/host ports attached to a switch (or vice-versa)
         *      we also need to invoke the 'txsync' code downstream.
         */
        void (*nm_dtor)(struct netmap_adapter *);

        int (*nm_register)(struct netmap_adapter *, int onoff);

        int (*nm_txsync)(struct netmap_kring *kring, int flags);
        int (*nm_rxsync)(struct netmap_kring *kring, int flags);
        int (*nm_notify)(struct netmap_kring *kring, int flags);
#define NAF_FORCE_READ    1
#define NAF_FORCE_RECLAIM 2
        /* return configuration information */
        int (*nm_config)(struct netmap_adapter *,
                u_int *txr, u_int *txd, u_int *rxr, u_int *rxd);
        int (*nm_krings_create)(struct netmap_adapter *);
        void (*nm_krings_delete)(struct netmap_adapter *);
#ifdef WITH_VALE
        /*
         * nm_bdg_attach() initializes the na_vp field to point
         *      to an adapter that can be attached to a VALE switch. If the
         *      current adapter is already a VALE port, na_vp is simply a cast;
         *      otherwise, na_vp points to a netmap_bwrap_adapter.
         *      If applicable, this callback also initializes na_hostvp,
         *      that can be used to connect the adapter host rings to the
         *      switch.
         *      Called with NMG_LOCK held.
         *
         * nm_bdg_ctl() is called on the actual attach/detach to/from
         *      to/from the switch, to perform adapter-specific
         *      initializations
         *      Called with NMG_LOCK held.
         */
        int (*nm_bdg_attach)(const char *bdg_name, struct netmap_adapter *);
        int (*nm_bdg_ctl)(struct netmap_adapter *, struct nmreq *, int);

        /* adapter used to attach this adapter to a VALE switch (if any) */
        struct netmap_vp_adapter *na_vp;
        /* adapter used to attach the host rings of this adapter
         * to a VALE switch (if any) */
        struct netmap_vp_adapter *na_hostvp;
#endif

        /* standard refcount to control the lifetime of the adapter
         * (it should be equal to the lifetime of the corresponding ifp)
         */
        int na_refcount;

        /* memory allocator (opaque)
         * We also cache a pointer to the lut_entry for translating
         * buffer addresses, and the total number of buffers.
         */
        struct netmap_mem_d *nm_mem;
        struct netmap_lut na_lut;

        /* additional information attached to this adapter
         * by other netmap subsystems. Currently used by
         * bwrap and LINUX/v1000.
         */
        void *na_private;

        /* array of pipes that have this adapter as a parent */
        struct netmap_pipe_adapter **na_pipes;
        int na_next_pipe;       /* next free slot in the array */
        int na_max_pipes;       /* size of the array */

        char name[64];
};

static __inline u_int
nma_get_ndesc(struct netmap_adapter *na, enum txrx t)
{
        return (t == NR_TX ? na->num_tx_desc : na->num_rx_desc);
}

static __inline void
nma_set_ndesc(struct netmap_adapter *na, enum txrx t, u_int v)
{
        if (t == NR_TX)
                na->num_tx_desc = v;
        else
                na->num_rx_desc = v;
}

static __inline u_int
nma_get_nrings(struct netmap_adapter *na, enum txrx t)
{
        return (t == NR_TX ? na->num_tx_rings : na->num_rx_rings);
}

static __inline void
nma_set_nrings(struct netmap_adapter *na, enum txrx t, u_int v)
{
        if (t == NR_TX)
                na->num_tx_rings = v;
        else
                na->num_rx_rings = v;
}

static __inline struct netmap_kring*
NMR(struct netmap_adapter *na, enum txrx t)
{
        return (t == NR_TX ? na->tx_rings : na->rx_rings);
}

/*
 * If the NIC is owned by the kernel
 * (i.e., bridge), neither another bridge nor user can use it;
 * if the NIC is owned by a user, only users can share it.
 * Evaluation must be done under NMG_LOCK().
 */
#define NETMAP_OWNED_BY_KERN(na)        ((na)->na_flags & NAF_BUSY)
#define NETMAP_OWNED_BY_ANY(na) \
        (NETMAP_OWNED_BY_KERN(na) || ((na)->active_fds > 0))

/*
 * derived netmap adapters for various types of ports
 */
struct netmap_vp_adapter {      /* VALE software port */
        struct netmap_adapter up;

        /*
         * Bridge support:
         *
         * bdg_port is the port number used in the bridge;
         * na_bdg points to the bridge this NA is attached to.
         */
        int bdg_port;
        struct nm_bridge *na_bdg;
        int retry;

        /* Offset of ethernet header for each packet. */
        u_int virt_hdr_len;
        /* Maximum Frame Size, used in bdg_mismatch_datapath() */
        u_int mfs;
        /* Last source MAC on this port */
        uint64_t last_smac;
};


struct netmap_hw_adapter {      /* physical device */
        struct netmap_adapter up;

        struct net_device_ops nm_ndo;   // XXX linux only
        struct ethtool_ops    nm_eto;   // XXX linux only
        const struct ethtool_ops*   save_ethtool;

        int (*nm_hw_register)(struct netmap_adapter *, int onoff);
};

#ifdef WITH_GENERIC
/* Mitigation support. */
struct nm_generic_mit {
        struct hrtimer mit_timer;
        int mit_pending;
        int mit_ring_idx;  /* index of the ring being mitigated */
        struct netmap_adapter *mit_na;  /* backpointer */
};

struct netmap_generic_adapter { /* emulated device */
        struct netmap_hw_adapter up;

        /* Pointer to a previously used netmap adapter. */
        struct netmap_adapter *prev;

        /* generic netmap adapters support:
         * a net_device_ops struct overrides ndo_select_queue(),
         * save_if_input saves the if_input hook (FreeBSD),
         * mit implements rx interrupt mitigation,
         */
        struct net_device_ops generic_ndo;
        void (*save_if_input)(struct ifnet *, struct mbuf *);

        struct nm_generic_mit *mit;
#ifdef linux
        netdev_tx_t (*save_start_xmit)(struct mbuf *, struct ifnet *);
#endif
};
#endif  /* WITH_GENERIC */

static __inline int
netmap_real_rings(struct netmap_adapter *na, enum txrx t)
{
        return nma_get_nrings(na, t) + !!(na->na_flags & NAF_HOST_RINGS);
}

#ifdef WITH_VALE

/*
 * Bridge wrapper for non VALE ports attached to a VALE switch.
 *
 * The real device must already have its own netmap adapter (hwna).
 * The bridge wrapper and the hwna adapter share the same set of
 * netmap rings and buffers, but they have two separate sets of
 * krings descriptors, with tx/rx meanings swapped:
 *
 *                                  netmap
 *           bwrap     krings       rings      krings      hwna
 *         +------+   +------+     +-----+    +------+   +------+
 *         |tx_rings->|      |\   /|     |----|      |<-tx_rings|
 *         |      |   +------+ \ / +-----+    +------+   |      |
 *         |      |             X                        |      |
 *         |      |            / \                       |      |
 *         |      |   +------+/   \+-----+    +------+   |      |
 *         |rx_rings->|      |     |     |----|      |<-rx_rings|
 *         |      |   +------+     +-----+    +------+   |      |
 *         +------+                                      +------+
 *
 * - packets coming from the bridge go to the brwap rx rings,
 *   which are also the hwna tx rings.  The bwrap notify callback
 *   will then complete the hwna tx (see netmap_bwrap_notify).
 *
 * - packets coming from the outside go to the hwna rx rings,
 *   which are also the bwrap tx rings.  The (overwritten) hwna
 *   notify method will then complete the bridge tx
 *   (see netmap_bwrap_intr_notify).
 *
 *   The bridge wrapper may optionally connect the hwna 'host' rings
 *   to the bridge. This is done by using a second port in the
 *   bridge and connecting it to the 'host' netmap_vp_adapter
 *   contained in the netmap_bwrap_adapter. The brwap host adapter
 *   cross-links the hwna host rings in the same way as shown above.
 *
 * - packets coming from the bridge and directed to the host stack
 *   are handled by the bwrap host notify callback
 *   (see netmap_bwrap_host_notify)
 *
 * - packets coming from the host stack are still handled by the
 *   overwritten hwna notify callback (netmap_bwrap_intr_notify),
 *   but are diverted to the host adapter depending on the ring number.
 *
 */
struct netmap_bwrap_adapter {
        struct netmap_vp_adapter up;
        struct netmap_vp_adapter host;  /* for host rings */
        struct netmap_adapter *hwna;    /* the underlying device */

        /* backup of the hwna memory allocator */
        struct netmap_mem_d *save_nmd;

        /*
         * When we attach a physical interface to the bridge, we
         * allow the controlling process to terminate, so we need
         * a place to store the n_detmap_priv_d data structure.
         * This is only done when physical interfaces
         * are attached to a bridge.
         */
        struct netmap_priv_d *na_kpriv;
};
int netmap_bwrap_attach(const char *name, struct netmap_adapter *);


#endif /* WITH_VALE */

#ifdef WITH_PIPES

#define NM_MAXPIPES     64      /* max number of pipes per adapter */

struct netmap_pipe_adapter {
        struct netmap_adapter up;

        u_int id;       /* pipe identifier */
        int role;       /* either NR_REG_PIPE_MASTER or NR_REG_PIPE_SLAVE */

        struct netmap_adapter *parent; /* adapter that owns the memory */
        struct netmap_pipe_adapter *peer; /* the other end of the pipe */
        int peer_ref;           /* 1 iff we are holding a ref to the peer */

        u_int parent_slot; /* index in the parent pipe array */
};

#endif /* WITH_PIPES */


/* return slots reserved to rx clients; used in drivers */
static inline uint32_t
nm_kr_rxspace(struct netmap_kring *k)
{
        int space = k->nr_hwtail - k->nr_hwcur;
        if (space < 0)
                space += k->nkr_num_slots;
        ND("preserving %d rx slots %d -> %d", space, k->nr_hwcur, k->nr_hwtail);

        return space;
}


/* True if no space in the tx ring. only valid after txsync_prologue */
static inline int
nm_kr_txempty(struct netmap_kring *kring)
{
        return kring->rcur == kring->nr_hwtail;
}


/*
 * protect against multiple threads using the same ring.
 * also check that the ring has not been stopped.
 * We only care for 0 or !=0 as a return code.
 */
#define NM_KR_BUSY      1
#define NM_KR_STOPPED   2


static __inline void nm_kr_put(struct netmap_kring *kr)
{
        NM_ATOMIC_CLEAR(&kr->nr_busy);
}


static __inline int nm_kr_tryget(struct netmap_kring *kr)
{
        /* check a first time without taking the lock
         * to avoid starvation for nm_kr_get()
         */
        if (unlikely(kr->nkr_stopped)) {
                ND("ring %p stopped (%d)", kr, kr->nkr_stopped);
                return NM_KR_STOPPED;
        }
        if (unlikely(NM_ATOMIC_TEST_AND_SET(&kr->nr_busy)))
                return NM_KR_BUSY;
        /* check a second time with lock held */
        if (unlikely(kr->nkr_stopped)) {
                ND("ring %p stopped (%d)", kr, kr->nkr_stopped);
                nm_kr_put(kr);
                return NM_KR_STOPPED;
        }
        return 0;
}

static __inline void nm_kr_get(struct netmap_kring *kr)
{
        while (NM_ATOMIC_TEST_AND_SET(&kr->nr_busy))
                tsleep(kr, 0, "NM_KR_GET", 4);
}


/*
 * The following functions are used by individual drivers to
 * support netmap operation.
 *
 * netmap_attach() initializes a struct netmap_adapter, allocating the
 *      struct netmap_ring's and the struct selinfo.
 *
 * netmap_detach() frees the memory allocated by netmap_attach().
 *
 * netmap_transmit() replaces the if_transmit routine of the interface,
 *      and is used to intercept packets coming from the stack.
 *
 * netmap_load_map/netmap_reload_map are helper routines to set/reset
 *      the dmamap for a packet buffer
 *
 * netmap_reset() is a helper routine to be called in the hw driver
 *      when reinitializing a ring. It should not be called by
 *      virtual ports (vale, pipes, monitor)
 */
int netmap_attach(struct netmap_adapter *);
void netmap_detach(struct ifnet *);
int netmap_transmit(struct ifnet *, struct mbuf *);
struct netmap_slot *netmap_reset(struct netmap_adapter *na,
        enum txrx tx, u_int n, u_int new_cur);
int netmap_ring_reinit(struct netmap_kring *);

/* default functions to handle rx/tx interrupts */
int netmap_rx_irq(struct ifnet *, u_int, u_int *);
#define netmap_tx_irq(_n, _q) netmap_rx_irq(_n, _q, NULL)
void netmap_common_irq(struct ifnet *, u_int, u_int *work_done);


#ifdef WITH_VALE
/* functions used by external modules to interface with VALE */
#define netmap_vp_to_ifp(_vp)   ((_vp)->up.ifp)
#define netmap_ifp_to_vp(_ifp)  (NA(_ifp)->na_vp)
#define netmap_ifp_to_host_vp(_ifp) (NA(_ifp)->na_hostvp)
#define netmap_bdg_idx(_vp)     ((_vp)->bdg_port)
const char *netmap_bdg_name(struct netmap_vp_adapter *);
#else /* !WITH_VALE */
#define netmap_vp_to_ifp(_vp)   NULL
#define netmap_ifp_to_vp(_ifp)  NULL
#define netmap_ifp_to_host_vp(_ifp) NULL
#define netmap_bdg_idx(_vp)     -1
#define netmap_bdg_name(_vp)    NULL
#endif /* WITH_VALE */

static inline int
nm_netmap_on(struct netmap_adapter *na)
{
        return na && na->na_flags & NAF_NETMAP_ON;
}

static inline int
nm_native_on(struct netmap_adapter *na)
{
        return nm_netmap_on(na) && (na->na_flags & NAF_NATIVE);
}

/* set/clear native flags and if_transmit/netdev_ops */
static inline void
nm_set_native_flags(struct netmap_adapter *na)
{
        struct ifnet *ifp = na->ifp;

        na->na_flags |= NAF_NETMAP_ON;
#ifdef IFCAP_NETMAP /* or FreeBSD ? */
        ifp->if_capenable |= IFCAP_NETMAP;
#endif
#ifdef __FreeBSD__
        na->if_transmit = ifp->if_transmit;
        ifp->if_transmit = netmap_transmit;
#else
        na->if_transmit = (void *)ifp->netdev_ops;
        ifp->netdev_ops = &((struct netmap_hw_adapter *)na)->nm_ndo;
        ((struct netmap_hw_adapter *)na)->save_ethtool = ifp->ethtool_ops;
        ifp->ethtool_ops = &((struct netmap_hw_adapter*)na)->nm_eto;
#endif
}


static inline void
nm_clear_native_flags(struct netmap_adapter *na)
{
        struct ifnet *ifp = na->ifp;

#ifdef __FreeBSD__
        ifp->if_transmit = na->if_transmit;
#else
        ifp->netdev_ops = (void *)na->if_transmit;
        ifp->ethtool_ops = ((struct netmap_hw_adapter*)na)->save_ethtool;
#endif
        na->na_flags &= ~NAF_NETMAP_ON;
#ifdef IFCAP_NETMAP /* or FreeBSD ? */
        ifp->if_capenable &= ~IFCAP_NETMAP;
#endif
}


/* check/fix address and len in tx rings */
#if 1 /* debug version */
#define NM_CHECK_ADDR_LEN(_na, _a, _l)  do {                            \
        if (_a == NETMAP_BUF_BASE(_na) || _l > NETMAP_BUF_SIZE(_na)) {  \
                RD(5, "bad addr/len ring %d slot %d idx %d len %d",     \
                        kring->ring_id, nm_i, slot->buf_idx, len);      \
                if (_l > NETMAP_BUF_SIZE(_na))                          \
                        _l = NETMAP_BUF_SIZE(_na);                      \
        } } while (0)
#else /* no debug version */
#define NM_CHECK_ADDR_LEN(_na, _a, _l)  do {                            \
                if (_l > NETMAP_BUF_SIZE(_na))                          \
                        _l = NETMAP_BUF_SIZE(_na);                      \
        } while (0)
#endif


/*---------------------------------------------------------------*/
/*
 * Support routines used by netmap subsystems
 * (native drivers, VALE, generic, pipes, monitors, ...)
 */


/* common routine for all functions that create a netmap adapter. It performs
 * two main tasks:
 * - if the na points to an ifp, mark the ifp as netmap capable
 *   using na as its native adapter;
 * - provide defaults for the setup callbacks and the memory allocator
 */
int netmap_attach_common(struct netmap_adapter *);
/* common actions to be performed on netmap adapter destruction */
void netmap_detach_common(struct netmap_adapter *);
/* fill priv->np_[tr]xq{first,last} using the ringid and flags information
 * coming from a struct nmreq
 */
int netmap_interp_ringid(struct netmap_priv_d *priv, uint16_t ringid, uint32_t flags);
/* update the ring parameters (number and size of tx and rx rings).
 * It calls the nm_config callback, if available.
 */
int netmap_update_config(struct netmap_adapter *na);
/* create and initialize the common fields of the krings array.
 * using the information that must be already available in the na.
 * tailroom can be used to request the allocation of additional
 * tailroom bytes after the krings array. This is used by
 * netmap_vp_adapter's (i.e., VALE ports) to make room for
 * leasing-related data structures
 */
int netmap_krings_create(struct netmap_adapter *na, u_int tailroom);
/* deletes the kring array of the adapter. The array must have
 * been created using netmap_krings_create
 */
void netmap_krings_delete(struct netmap_adapter *na);

/* set the stopped/enabled status of ring
 * When stopping, they also wait for all current activity on the ring to
 * terminate. The status change is then notified using the na nm_notify
 * callback.
 */
void netmap_set_ring(struct netmap_adapter *, u_int ring_id, enum txrx, int stopped);
/* set the stopped/enabled status of all rings of the adapter. */
void netmap_set_all_rings(struct netmap_adapter *, int stopped);
/* convenience wrappers for netmap_set_all_rings, used in drivers */
void netmap_disable_all_rings(struct ifnet *);
void netmap_enable_all_rings(struct ifnet *);

int netmap_do_regif(struct netmap_priv_d *priv, struct netmap_adapter *na,
        uint16_t ringid, uint32_t flags);


u_int nm_bound_var(u_int *v, u_int dflt, u_int lo, u_int hi, const char *msg);
int netmap_get_na(struct nmreq *nmr, struct netmap_adapter **na, int create);
int netmap_get_hw_na(struct ifnet *ifp, struct netmap_adapter **na);


#ifdef WITH_VALE
/*
 * The following bridge-related functions are used by other
 * kernel modules.
 *
 * VALE only supports unicast or broadcast. The lookup
 * function can return 0 .. NM_BDG_MAXPORTS-1 for regular ports,
 * NM_BDG_MAXPORTS for broadcast, NM_BDG_MAXPORTS+1 for unknown.
 * XXX in practice "unknown" might be handled same as broadcast.
 */
typedef u_int (*bdg_lookup_fn_t)(struct nm_bdg_fwd *ft, uint8_t *ring_nr,
                struct netmap_vp_adapter *);
typedef int (*bdg_config_fn_t)(struct nm_ifreq *);
typedef void (*bdg_dtor_fn_t)(const struct netmap_vp_adapter *);
struct netmap_bdg_ops {
        bdg_lookup_fn_t lookup;
        bdg_config_fn_t config;
        bdg_dtor_fn_t   dtor;
};

u_int netmap_bdg_learning(struct nm_bdg_fwd *ft, uint8_t *dst_ring,
                struct netmap_vp_adapter *);

#define NM_BDG_MAXPORTS         254     /* up to 254 */
#define NM_BDG_BROADCAST        NM_BDG_MAXPORTS
#define NM_BDG_NOPORT           (NM_BDG_MAXPORTS+1)

#define NM_NAME                 "vale"  /* prefix for bridge port name */

/* these are redefined in case of no VALE support */
int netmap_get_bdg_na(struct nmreq *nmr, struct netmap_adapter **na, int create);
struct nm_bridge *netmap_init_bridges2(u_int);
void netmap_uninit_bridges2(struct nm_bridge *, u_int);
int netmap_init_bridges(void);
void netmap_uninit_bridges(void);
int netmap_bdg_ctl(struct nmreq *nmr, struct netmap_bdg_ops *bdg_ops);
int netmap_bdg_config(struct nmreq *nmr);

#else /* !WITH_VALE */
#define netmap_get_bdg_na(_1, _2, _3)   0
#define netmap_init_bridges(_1) 0
#define netmap_uninit_bridges()
#define netmap_bdg_ctl(_1, _2)  EINVAL
#endif /* !WITH_VALE */

#ifdef WITH_PIPES
/* max number of pipes per device */
#define NM_MAXPIPES     64      /* XXX how many? */
void netmap_pipe_dealloc(struct netmap_adapter *);
int netmap_get_pipe_na(struct nmreq *nmr, struct netmap_adapter **na, int create);
#else /* !WITH_PIPES */
#define NM_MAXPIPES     0
#define netmap_pipe_alloc(_1, _2)       0
#define netmap_pipe_dealloc(_1)
#define netmap_get_pipe_na(nmr, _2, _3) \
        ({ int role__ = (nmr)->nr_flags & NR_REG_MASK; \
           (role__ == NR_REG_PIPE_MASTER ||            \
            role__ == NR_REG_PIPE_SLAVE) ? EOPNOTSUPP : 0; })
#endif

#ifdef WITH_MONITOR
int netmap_get_monitor_na(struct nmreq *nmr, struct netmap_adapter **na, int create);
void netmap_monitor_stop(struct netmap_adapter *na);
#else
#define netmap_get_monitor_na(nmr, _2, _3) \
        ((nmr)->nr_flags & (NR_MONITOR_TX | NR_MONITOR_RX) ? EOPNOTSUPP : 0)
#endif

#ifdef CONFIG_NET_NS
struct net *netmap_bns_get(void);
void netmap_bns_put(struct net *);
void netmap_bns_getbridges(struct nm_bridge **, u_int *);
#else
#define netmap_bns_get()
#define netmap_bns_put(_1)
#define netmap_bns_getbridges(b, n) \
        do { *b = nm_bridges; *n = NM_BRIDGES; } while (0)
#endif

/* Various prototypes */
int netmap_poll(struct cdev *dev, int events, struct thread *td);
int netmap_init(void);
void netmap_fini(void);
int netmap_get_memory(struct netmap_priv_d* p);
void netmap_dtor(void *data);
int netmap_dtor_locked(struct netmap_priv_d *priv);

int netmap_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag, struct thread *td);

/* netmap_adapter creation/destruction */

// #define NM_DEBUG_PUTGET 1

#ifdef NM_DEBUG_PUTGET

#define NM_DBG(f) __##f

void __netmap_adapter_get(struct netmap_adapter *na);

#define netmap_adapter_get(na)                          \
        do {                                            \
                struct netmap_adapter *__na = na;       \
                D("getting %p:%s (%d)", __na, (__na)->name, (__na)->na_refcount);       \
                __netmap_adapter_get(__na);             \
        } while (0)

int __netmap_adapter_put(struct netmap_adapter *na);

#define netmap_adapter_put(na)                          \
        ({                                              \
                struct netmap_adapter *__na = na;       \
                D("putting %p:%s (%d)", __na, (__na)->name, (__na)->na_refcount);       \
                __netmap_adapter_put(__na);             \
        })

#else /* !NM_DEBUG_PUTGET */

#define NM_DBG(f) f
void netmap_adapter_get(struct netmap_adapter *na);
int netmap_adapter_put(struct netmap_adapter *na);

#endif /* !NM_DEBUG_PUTGET */


/*
 * module variables
 */
#define NETMAP_BUF_BASE(na)     ((na)->na_lut.lut[0].vaddr)
#define NETMAP_BUF_SIZE(na)     ((na)->na_lut.objsize)
extern int netmap_mitigate;     // XXX not really used
extern int netmap_no_pendintr;
extern int netmap_verbose;      // XXX debugging
enum {                                  /* verbose flags */
        NM_VERB_ON = 1,                 /* generic verbose */
        NM_VERB_HOST = 0x2,             /* verbose host stack */
        NM_VERB_RXSYNC = 0x10,          /* verbose on rxsync/txsync */
        NM_VERB_TXSYNC = 0x20,
        NM_VERB_RXINTR = 0x100,         /* verbose on rx/tx intr (driver) */
        NM_VERB_TXINTR = 0x200,
        NM_VERB_NIC_RXSYNC = 0x1000,    /* verbose on rx/tx intr (driver) */
        NM_VERB_NIC_TXSYNC = 0x2000,
};

extern int netmap_txsync_retry;
extern int netmap_generic_mit;
extern int netmap_generic_ringsize;
extern int netmap_generic_rings;
extern int netmap_use_count;

/*
 * NA returns a pointer to the struct netmap adapter from the ifp,
 * WNA is used to write it.
 */
#define NA(_ifp)        ((struct netmap_adapter *)WNA(_ifp))

/*
 * Macros to determine if an interface is netmap capable or netmap enabled.
 * See the magic field in struct netmap_adapter.
 */
#ifdef __FreeBSD__
/*
 * on FreeBSD just use if_capabilities and if_capenable.
 */
#define NETMAP_CAPABLE(ifp)     (NA(ifp) &&             \
        (ifp)->if_capabilities & IFCAP_NETMAP )

#define NETMAP_SET_CAPABLE(ifp)                         \
        (ifp)->if_capabilities |= IFCAP_NETMAP

#else   /* linux */

/*
 * on linux:
 * we check if NA(ifp) is set and its first element has a related
 * magic value. The capenable is within the struct netmap_adapter.
 */
#define NETMAP_MAGIC    0x52697a7a

#define NETMAP_CAPABLE(ifp)     (NA(ifp) &&             \
        ((uint32_t)(uintptr_t)NA(ifp) ^ NA(ifp)->magic) == NETMAP_MAGIC )

#define NETMAP_SET_CAPABLE(ifp)                         \
        NA(ifp)->magic = ((uint32_t)(uintptr_t)NA(ifp)) ^ NETMAP_MAGIC

#endif  /* linux */

#ifdef __FreeBSD__

/* Assigns the device IOMMU domain to an allocator.
 * Returns -ENOMEM in case the domain is different */
#define nm_iommu_group_id(dev) (0)

/* Callback invoked by the dma machinery after a successful dmamap_load */
static void netmap_dmamap_cb(__unused void *arg,
    __unused bus_dma_segment_t * segs, __unused int nseg, __unused int error)
{
}

/* bus_dmamap_load wrapper: call aforementioned function if map != NULL.
 * XXX can we do it without a callback ?
 */
static inline void
netmap_load_map(struct netmap_adapter *na,
        bus_dma_tag_t tag, bus_dmamap_t map, void *buf)
{
        if (map)
                bus_dmamap_load(tag, map, buf, NETMAP_BUF_SIZE(na),
                    netmap_dmamap_cb, NULL, BUS_DMA_NOWAIT);
}

static inline void
netmap_unload_map(struct netmap_adapter *na,
        bus_dma_tag_t tag, bus_dmamap_t map)
{
        if (map)
                bus_dmamap_unload(tag, map);
}

/* update the map when a buffer changes. */
static inline void
netmap_reload_map(struct netmap_adapter *na,
        bus_dma_tag_t tag, bus_dmamap_t map, void *buf)
{
        if (map) {
                bus_dmamap_unload(tag, map);
                bus_dmamap_load(tag, map, buf, NETMAP_BUF_SIZE(na),
                    netmap_dmamap_cb, NULL, BUS_DMA_NOWAIT);
        }
}

#else /* linux */

int nm_iommu_group_id(bus_dma_tag_t dev);
#include <linux/dma-mapping.h>

static inline void
netmap_load_map(struct netmap_adapter *na,
        bus_dma_tag_t tag, bus_dmamap_t map, void *buf)
{
        if (0 && map) {
                *map = dma_map_single(na->pdev, buf, na->na_lut.objsize,
                                DMA_BIDIRECTIONAL);
        }
}

static inline void
netmap_unload_map(struct netmap_adapter *na,
        bus_dma_tag_t tag, bus_dmamap_t map)
{
        u_int sz = na->na_lut.objsize;

        if (*map) {
                dma_unmap_single(na->pdev, *map, sz,
                                DMA_BIDIRECTIONAL);
        }
}

static inline void
netmap_reload_map(struct netmap_adapter *na,
        bus_dma_tag_t tag, bus_dmamap_t map, void *buf)
{
        u_int sz = na->na_lut.objsize;

        if (*map) {
                dma_unmap_single(na->pdev, *map, sz,
                                DMA_BIDIRECTIONAL);
        }

        *map = dma_map_single(na->pdev, buf, sz,
                                DMA_BIDIRECTIONAL);
}

/*
 * XXX How do we redefine these functions:
 *
 * on linux we need
 *      dma_map_single(&pdev->dev, virt_addr, len, direction)
 *      dma_unmap_single(&adapter->pdev->dev, phys_addr, len, direction
 * The len can be implicit (on netmap it is NETMAP_BUF_SIZE)
 * unfortunately the direction is not, so we need to change
 * something to have a cross API
 */

#if 0
        struct e1000_buffer *buffer_info =  &tx_ring->buffer_info[l];
        /* set time_stamp *before* dma to help avoid a possible race */
        buffer_info->time_stamp = jiffies;
        buffer_info->mapped_as_page = false;
        buffer_info->length = len;
        //buffer_info->next_to_watch = l;
        /* reload dma map */
        dma_unmap_single(&adapter->pdev->dev, buffer_info->dma,
                        NETMAP_BUF_SIZE, DMA_TO_DEVICE);
        buffer_info->dma = dma_map_single(&adapter->pdev->dev,
                        addr, NETMAP_BUF_SIZE, DMA_TO_DEVICE);

        if (dma_mapping_error(&adapter->pdev->dev, buffer_info->dma)) {
                D("dma mapping error");
                /* goto dma_error; See e1000_put_txbuf() */
                /* XXX reset */
        }
        tx_desc->buffer_addr = htole64(buffer_info->dma); //XXX

#endif

/*
 * The bus_dmamap_sync() can be one of wmb() or rmb() depending on direction.
 */
#define bus_dmamap_sync(_a, _b, _c)

#endif /* linux */


/*
 * functions to map NIC to KRING indexes (n2k) and vice versa (k2n)
 */
static inline int
netmap_idx_n2k(struct netmap_kring *kr, int idx)
{
        int n = kr->nkr_num_slots;
        idx += kr->nkr_hwofs;
        if (idx < 0)
                return idx + n;
        else if (idx < n)
                return idx;
        else
                return idx - n;
}


static inline int
netmap_idx_k2n(struct netmap_kring *kr, int idx)
{
        int n = kr->nkr_num_slots;
        idx -= kr->nkr_hwofs;
        if (idx < 0)
                return idx + n;
        else if (idx < n)
                return idx;
        else
                return idx - n;
}


/* Entries of the look-up table. */
struct lut_entry {
        void *vaddr;            /* virtual address. */
        vm_paddr_t paddr;       /* physical address. */
};

struct netmap_obj_pool;

/*
 * NMB return the virtual address of a buffer (buffer 0 on bad index)
 * PNMB also fills the physical address
 */
static inline void *
NMB(struct netmap_adapter *na, struct netmap_slot *slot)
{
        struct lut_entry *lut = na->na_lut.lut;
        uint32_t i = slot->buf_idx;
        return (unlikely(i >= na->na_lut.objtotal)) ?
                lut[0].vaddr : lut[i].vaddr;
}

static inline void *
PNMB(struct netmap_adapter *na, struct netmap_slot *slot, uint64_t *pp)
{
        uint32_t i = slot->buf_idx;
        struct lut_entry *lut = na->na_lut.lut;
        void *ret = (i >= na->na_lut.objtotal) ? lut[0].vaddr : lut[i].vaddr;

        *pp = (i >= na->na_lut.objtotal) ? lut[0].paddr : lut[i].paddr;
        return ret;
}


/*
 * Structure associated to each netmap file descriptor.
 * It is created on open and left unbound (np_nifp == NULL).
 * A successful NIOCREGIF will set np_nifp and the first few fields;
 * this is protected by a global lock (NMG_LOCK) due to low contention.
 *
 * np_refs counts the number of references to the structure: one for the fd,
 * plus (on FreeBSD) one for each active mmap which we track ourselves
 * (linux automatically tracks them, but FreeBSD does not).
 * np_refs is protected by NMG_LOCK.
 *
 * Read access to the structure is lock free, because ni_nifp once set
 * can only go to 0 when nobody is using the entry anymore. Readers
 * must check that np_nifp != NULL before using the other fields.
 */
struct netmap_priv_d {
        struct netmap_if * volatile np_nifp;    /* netmap if descriptor. */

        struct netmap_adapter   *np_na;
        uint32_t        np_flags;       /* from the ioctl */
        u_int           np_qfirst[NR_TXRX], 
                        np_qlast[NR_TXRX]; /* range of tx/rx rings to scan */
        uint16_t        np_txpoll;      /* XXX and also np_rxpoll ? */

        int             np_refs;        /* use with NMG_LOCK held */

        /* pointers to the selinfo to be used for selrecord.
         * Either the local or the global one depending on the
         * number of rings.
         */
        NM_SELINFO_T *np_si[NR_TXRX];
        struct thread   *np_td;         /* kqueue, just debugging */
};

#ifdef WITH_MONITOR

struct netmap_monitor_adapter {
        struct netmap_adapter up;

        struct netmap_priv_d priv;
        uint32_t flags;
};

#endif /* WITH_MONITOR */


#ifdef WITH_GENERIC
/*
 * generic netmap emulation for devices that do not have
 * native netmap support.
 */
int generic_netmap_attach(struct ifnet *ifp);

int netmap_catch_rx(struct netmap_generic_adapter *na, int intercept);
void generic_rx_handler(struct ifnet *ifp, struct mbuf *m);;
void netmap_catch_tx(struct netmap_generic_adapter *na, int enable);
int generic_xmit_frame(struct ifnet *ifp, struct mbuf *m, void *addr, u_int len, u_int ring_nr);
int generic_find_num_desc(struct ifnet *ifp, u_int *tx, u_int *rx);
void generic_find_num_queues(struct ifnet *ifp, u_int *txq, u_int *rxq);
static inline struct ifnet*
netmap_generic_getifp(struct netmap_generic_adapter *gna)
{
        if (gna->prev)
            return gna->prev->ifp;

        return gna->up.up.ifp;
}

//#define RATE_GENERIC  /* Enables communication statistics for generic. */
#ifdef RATE_GENERIC
void generic_rate(int txp, int txs, int txi, int rxp, int rxs, int rxi);
#else
#define generic_rate(txp, txs, txi, rxp, rxs, rxi)
#endif

/*
 * netmap_mitigation API. This is used by the generic adapter
 * to reduce the number of interrupt requests/selwakeup
 * to clients on incoming packets.
 */
void netmap_mitigation_init(struct nm_generic_mit *mit, int idx,
                                struct netmap_adapter *na);
void netmap_mitigation_start(struct nm_generic_mit *mit);
void netmap_mitigation_restart(struct nm_generic_mit *mit);
int netmap_mitigation_active(struct nm_generic_mit *mit);
void netmap_mitigation_cleanup(struct nm_generic_mit *mit);
#endif /* WITH_GENERIC */



/* Shared declarations for the VALE switch. */

/*
 * Each transmit queue accumulates a batch of packets into
 * a structure before forwarding. Packets to the same
 * destination are put in a list using ft_next as a link field.
 * ft_frags and ft_next are valid only on the first fragment.
 */
struct nm_bdg_fwd {     /* forwarding entry for a bridge */
        void *ft_buf;           /* netmap or indirect buffer */
        uint8_t ft_frags;       /* how many fragments (only on 1st frag) */
        uint8_t _ft_port;       /* dst port (unused) */
        uint16_t ft_flags;      /* flags, e.g. indirect */
        uint16_t ft_len;        /* src fragment len */
        uint16_t ft_next;       /* next packet to same destination */
};

/* struct 'virtio_net_hdr' from linux. */
struct nm_vnet_hdr {
#define VIRTIO_NET_HDR_F_NEEDS_CSUM     1       /* Use csum_start, csum_offset */
#define VIRTIO_NET_HDR_F_DATA_VALID    2        /* Csum is valid */
    uint8_t flags;
#define VIRTIO_NET_HDR_GSO_NONE         0       /* Not a GSO frame */
#define VIRTIO_NET_HDR_GSO_TCPV4        1       /* GSO frame, IPv4 TCP (TSO) */
#define VIRTIO_NET_HDR_GSO_UDP          3       /* GSO frame, IPv4 UDP (UFO) */
#define VIRTIO_NET_HDR_GSO_TCPV6        4       /* GSO frame, IPv6 TCP */
#define VIRTIO_NET_HDR_GSO_ECN          0x80    /* TCP has ECN set */
    uint8_t gso_type;
    uint16_t hdr_len;
    uint16_t gso_size;
    uint16_t csum_start;
    uint16_t csum_offset;
};

#define WORST_CASE_GSO_HEADER   (14+40+60)  /* IPv6 + TCP */

/* Private definitions for IPv4, IPv6, UDP and TCP headers. */

struct nm_iphdr {
        uint8_t         version_ihl;
        uint8_t         tos;
        uint16_t        tot_len;
        uint16_t        id;
        uint16_t        frag_off;
        uint8_t         ttl;
        uint8_t         protocol;
        uint16_t        check;
        uint32_t        saddr;
        uint32_t        daddr;
        /*The options start here. */
};

struct nm_tcphdr {
        uint16_t        source;
        uint16_t        dest;
        uint32_t        seq;
        uint32_t        ack_seq;
        uint8_t         doff;  /* Data offset + Reserved */
        uint8_t         flags;
        uint16_t        window;
        uint16_t        check;
        uint16_t        urg_ptr;
};

struct nm_udphdr {
        uint16_t        source;
        uint16_t        dest;
        uint16_t        len;
        uint16_t        check;
};

struct nm_ipv6hdr {
        uint8_t         priority_version;
        uint8_t         flow_lbl[3];

        uint16_t        payload_len;
        uint8_t         nexthdr;
        uint8_t         hop_limit;

        uint8_t         saddr[16];
        uint8_t         daddr[16];
};

/* Type used to store a checksum (in host byte order) that hasn't been
 * folded yet.
 */
#define rawsum_t uint32_t

rawsum_t nm_csum_raw(uint8_t *data, size_t len, rawsum_t cur_sum);
uint16_t nm_csum_ipv4(struct nm_iphdr *iph);
void nm_csum_tcpudp_ipv4(struct nm_iphdr *iph, void *data,
                      size_t datalen, uint16_t *check);
void nm_csum_tcpudp_ipv6(struct nm_ipv6hdr *ip6h, void *data,
                      size_t datalen, uint16_t *check);
uint16_t nm_csum_fold(rawsum_t cur_sum);

void bdg_mismatch_datapath(struct netmap_vp_adapter *na,
                           struct netmap_vp_adapter *dst_na,
                           struct nm_bdg_fwd *ft_p, struct netmap_ring *ring,
                           u_int *j, u_int lim, u_int *howmany);

/* persistent virtual port routines */
int nm_vi_persist(const char *, struct ifnet **);
void nm_vi_detach(struct ifnet *);
void nm_vi_init_index(void);

#endif /* _NET_NETMAP_KERN_H_ */