FreeBSD/Linux Kernel Cross Reference
sys/dev/netmap/netmap_freebsd.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * 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.
     */
    
    /* $FreeBSD$ */
    #include "opt_inet.h"
    #include "opt_inet6.h"
    
    #include <sys/param.h>
    #include <sys/module.h>
    #include <sys/errno.h>
    #include <sys/eventhandler.h>
    #include <sys/jail.h>
    #include <sys/poll.h>  /* POLLIN, POLLOUT */
    #include <sys/kernel.h> /* types used in module initialization */
    #include <sys/conf.h>   /* DEV_MODULE_ORDERED */
    #include <sys/endian.h>
    #include <sys/syscallsubr.h> /* kern_ioctl() */
    
    #include <sys/rwlock.h>
    
    #include <vm/vm.h>      /* vtophys */
    #include <vm/pmap.h>    /* vtophys */
    #include <vm/vm_param.h>
    #include <vm/vm_object.h>
    #include <vm/vm_page.h>
    #include <vm/vm_pager.h>
    #include <vm/uma.h>
    
    
    #include <sys/malloc.h>
    #include <sys/socket.h> /* sockaddrs */
    #include <sys/selinfo.h>
    #include <sys/kthread.h> /* kthread_add() */
    #include <sys/proc.h> /* PROC_LOCK() */
    #include <sys/unistd.h> /* RFNOWAIT */
    #include <sys/sched.h> /* sched_bind() */
    #include <sys/smp.h> /* mp_maxid */
    #include <sys/taskqueue.h> /* taskqueue_enqueue(), taskqueue_create(), ... */
    #include <net/if.h>
    #include <net/if_var.h>
    #include <net/if_types.h> /* IFT_ETHER */
    #include <net/ethernet.h> /* ether_ifdetach */
    #include <net/if_dl.h> /* LLADDR */
    #include <machine/bus.h>        /* bus_dmamap_* */
    #include <netinet/in.h>         /* in6_cksum_pseudo() */
    #include <machine/in_cksum.h>  /* in_pseudo(), in_cksum_hdr() */
    
    #include <net/netmap.h>
    #include <dev/netmap/netmap_kern.h>
    #include <net/netmap_virt.h>
    #include <dev/netmap/netmap_mem2.h>
    
    
    /* ======================== FREEBSD-SPECIFIC ROUTINES ================== */
    
    static void
    nm_kqueue_notify(void *opaque, int pending)
    {
            struct nm_selinfo *si = opaque;
    
            /* We use a non-zero hint to distinguish this notification call
             * from the call done in kqueue_scan(), which uses hint=0.
             */
            KNOTE_UNLOCKED(&si->si.si_note, /*hint=*/0x100);
    }
    
    int nm_os_selinfo_init(NM_SELINFO_T *si, const char *name) {
            int err;
    
            TASK_INIT(&si->ntfytask, 0, nm_kqueue_notify, si);
            si->ntfytq = taskqueue_create(name, M_NOWAIT,
                taskqueue_thread_enqueue, &si->ntfytq);
            if (si->ntfytq == NULL)
                    return -ENOMEM;
            err = taskqueue_start_threads(&si->ntfytq, 1, PI_NET, "tq %s", name);
           if (err) {
                   taskqueue_free(si->ntfytq);
                   si->ntfytq = NULL;
                   return err;
           }
   
           snprintf(si->mtxname, sizeof(si->mtxname), "nmkl%s", name);
           mtx_init(&si->m, si->mtxname, NULL, MTX_DEF);
           knlist_init_mtx(&si->si.si_note, &si->m);
           si->kqueue_users = 0;
   
           return (0);
   }
   
   void
   nm_os_selinfo_uninit(NM_SELINFO_T *si)
   {
           if (si->ntfytq == NULL) {
                   return; /* si was not initialized */
           }
           taskqueue_drain(si->ntfytq, &si->ntfytask);
           taskqueue_free(si->ntfytq);
           si->ntfytq = NULL;
           knlist_delete(&si->si.si_note, curthread, /*islocked=*/0);
           knlist_destroy(&si->si.si_note);
           /* now we don't need the mutex anymore */
           mtx_destroy(&si->m);
   }
   
   void *
   nm_os_malloc(size_t size)
   {
           return malloc(size, M_DEVBUF, M_NOWAIT | M_ZERO);
   }
   
   void *
   nm_os_realloc(void *addr, size_t new_size, size_t old_size __unused)
   {
           return realloc(addr, new_size, M_DEVBUF, M_NOWAIT | M_ZERO);
   }
   
   void
   nm_os_free(void *addr)
   {
           free(addr, M_DEVBUF);
   }
   
   void
   nm_os_ifnet_lock(void)
   {
           IFNET_RLOCK();
   }
   
   void
   nm_os_ifnet_unlock(void)
   {
           IFNET_RUNLOCK();
   }
   
   static int netmap_use_count = 0;
   
   void
   nm_os_get_module(void)
   {
           netmap_use_count++;
   }
   
   void
   nm_os_put_module(void)
   {
           netmap_use_count--;
   }
   
   static void
   netmap_ifnet_arrival_handler(void *arg __unused, struct ifnet *ifp)
   {
           netmap_undo_zombie(ifp);
   }
   
   static void
   netmap_ifnet_departure_handler(void *arg __unused, struct ifnet *ifp)
   {
           netmap_make_zombie(ifp);
   }
   
   static eventhandler_tag nm_ifnet_ah_tag;
   static eventhandler_tag nm_ifnet_dh_tag;
   
   int
   nm_os_ifnet_init(void)
   {
           nm_ifnet_ah_tag =
                   EVENTHANDLER_REGISTER(ifnet_arrival_event,
                                   netmap_ifnet_arrival_handler,
                                   NULL, EVENTHANDLER_PRI_ANY);
           nm_ifnet_dh_tag =
                   EVENTHANDLER_REGISTER(ifnet_departure_event,
                                   netmap_ifnet_departure_handler,
                                   NULL, EVENTHANDLER_PRI_ANY);
           return 0;
   }
   
   void
   nm_os_ifnet_fini(void)
   {
           EVENTHANDLER_DEREGISTER(ifnet_arrival_event,
                           nm_ifnet_ah_tag);
           EVENTHANDLER_DEREGISTER(ifnet_departure_event,
                           nm_ifnet_dh_tag);
   }
   
   unsigned
   nm_os_ifnet_mtu(struct ifnet *ifp)
   {
           return ifp->if_mtu;
   }
   
   rawsum_t
   nm_os_csum_raw(uint8_t *data, size_t len, rawsum_t cur_sum)
   {
           /* TODO XXX please use the FreeBSD implementation for this. */
           uint16_t *words = (uint16_t *)data;
           int nw = len / 2;
           int i;
   
           for (i = 0; i < nw; i++)
                   cur_sum += be16toh(words[i]);
   
           if (len & 1)
                   cur_sum += (data[len-1] << 8);
   
           return cur_sum;
   }
   
   /* Fold a raw checksum: 'cur_sum' is in host byte order, while the
    * return value is in network byte order.
    */
   uint16_t
   nm_os_csum_fold(rawsum_t cur_sum)
   {
           /* TODO XXX please use the FreeBSD implementation for this. */
           while (cur_sum >> 16)
                   cur_sum = (cur_sum & 0xFFFF) + (cur_sum >> 16);
   
           return htobe16((~cur_sum) & 0xFFFF);
   }
   
   uint16_t nm_os_csum_ipv4(struct nm_iphdr *iph)
   {
   #if 0
           return in_cksum_hdr((void *)iph);
   #else
           return nm_os_csum_fold(nm_os_csum_raw((uint8_t*)iph, sizeof(struct nm_iphdr), 0));
   #endif
   }
   
   void
   nm_os_csum_tcpudp_ipv4(struct nm_iphdr *iph, void *data,
                                           size_t datalen, uint16_t *check)
   {
   #ifdef INET
           uint16_t pseudolen = datalen + iph->protocol;
   
           /* Compute and insert the pseudo-header checksum. */
           *check = in_pseudo(iph->saddr, iph->daddr,
                                    htobe16(pseudolen));
           /* Compute the checksum on TCP/UDP header + payload
            * (includes the pseudo-header).
            */
           *check = nm_os_csum_fold(nm_os_csum_raw(data, datalen, 0));
   #else
           static int notsupported = 0;
           if (!notsupported) {
                   notsupported = 1;
                   nm_prerr("inet4 segmentation not supported");
           }
   #endif
   }
   
   void
   nm_os_csum_tcpudp_ipv6(struct nm_ipv6hdr *ip6h, void *data,
                                           size_t datalen, uint16_t *check)
   {
   #ifdef INET6
           *check = in6_cksum_pseudo((void*)ip6h, datalen, ip6h->nexthdr, 0);
           *check = nm_os_csum_fold(nm_os_csum_raw(data, datalen, 0));
   #else
           static int notsupported = 0;
           if (!notsupported) {
                   notsupported = 1;
                   nm_prerr("inet6 segmentation not supported");
           }
   #endif
   }
   
   /* on FreeBSD we send up one packet at a time */
   void *
   nm_os_send_up(struct ifnet *ifp, struct mbuf *m, struct mbuf *prev)
   {
           NA(ifp)->if_input(ifp, m);
           return NULL;
   }
   
   int
   nm_os_mbuf_has_csum_offld(struct mbuf *m)
   {
           return m->m_pkthdr.csum_flags & (CSUM_TCP | CSUM_UDP | CSUM_SCTP |
                                            CSUM_TCP_IPV6 | CSUM_UDP_IPV6 |
                                            CSUM_SCTP_IPV6);
   }
   
   int
   nm_os_mbuf_has_seg_offld(struct mbuf *m)
   {
           return m->m_pkthdr.csum_flags & CSUM_TSO;
   }
   
   static void
   freebsd_generic_rx_handler(struct ifnet *ifp, struct mbuf *m)
   {
           int stolen;
   
           if (unlikely(!NM_NA_VALID(ifp))) {
                   nm_prlim(1, "Warning: RX packet intercepted, but no"
                                   " emulated adapter");
                   return;
           }
   
           stolen = generic_rx_handler(ifp, m);
           if (!stolen) {
                   struct netmap_generic_adapter *gna =
                                   (struct netmap_generic_adapter *)NA(ifp);
                   gna->save_if_input(ifp, m);
           }
   }
   
   /*
    * Intercept the rx routine in the standard device driver.
    * Second argument is non-zero to intercept, 0 to restore
    */
   int
   nm_os_catch_rx(struct netmap_generic_adapter *gna, int intercept)
   {
           struct netmap_adapter *na = &gna->up.up;
           struct ifnet *ifp = na->ifp;
           int ret = 0;
   
           nm_os_ifnet_lock();
           if (intercept) {
                   if (gna->save_if_input) {
                           nm_prerr("RX on %s already intercepted", na->name);
                           ret = EBUSY; /* already set */
                           goto out;
                   }
   
                   ifp->if_capenable |= IFCAP_NETMAP;
                   gna->save_if_input = ifp->if_input;
                   ifp->if_input = freebsd_generic_rx_handler;
           } else {
                   if (!gna->save_if_input) {
                           nm_prerr("Failed to undo RX intercept on %s",
                                   na->name);
                           ret = EINVAL;  /* not saved */
                           goto out;
                   }
   
                   ifp->if_capenable &= ~IFCAP_NETMAP;
                   ifp->if_input = gna->save_if_input;
                   gna->save_if_input = NULL;
           }
   out:
           nm_os_ifnet_unlock();
   
           return ret;
   }
   
   
   /*
    * Intercept the packet steering routine in the tx path,
    * so that we can decide which queue is used for an mbuf.
    * Second argument is non-zero to intercept, 0 to restore.
    * On freebsd we just intercept if_transmit.
    */
   int
   nm_os_catch_tx(struct netmap_generic_adapter *gna, int intercept)
   {
           struct netmap_adapter *na = &gna->up.up;
           struct ifnet *ifp = netmap_generic_getifp(gna);
   
           nm_os_ifnet_lock();
           if (intercept) {
                   na->if_transmit = ifp->if_transmit;
                   ifp->if_transmit = netmap_transmit;
           } else {
                   ifp->if_transmit = na->if_transmit;
           }
           nm_os_ifnet_unlock();
   
           return 0;
   }
   
   
   /*
    * Transmit routine used by generic_netmap_txsync(). Returns 0 on success
    * and non-zero on error (which may be packet drops or other errors).
    * addr and len identify the netmap buffer, m is the (preallocated)
    * mbuf to use for transmissions.
    *
    * We should add a reference to the mbuf so the m_freem() at the end
    * of the transmission does not consume resources.
    *
    * On FreeBSD, and on multiqueue cards, we can force the queue using
    *      if (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE)
    *              i = m->m_pkthdr.flowid % adapter->num_queues;
    *      else
    *              i = curcpu % adapter->num_queues;
    *
    */
   int
   nm_os_generic_xmit_frame(struct nm_os_gen_arg *a)
   {
           int ret;
           u_int len = a->len;
           struct ifnet *ifp = a->ifp;
           struct mbuf *m = a->m;
   
           /* Link the external storage to
            * the netmap buffer, so that no copy is necessary. */
           m->m_ext.ext_buf = m->m_data = a->addr;
           m->m_ext.ext_size = len;
   
           m->m_flags |= M_PKTHDR;
           m->m_len = m->m_pkthdr.len = len;
   
           /* mbuf refcnt is not contended, no need to use atomic
            * (a memory barrier is enough). */
           SET_MBUF_REFCNT(m, 2);
           M_HASHTYPE_SET(m, M_HASHTYPE_OPAQUE);
           m->m_pkthdr.flowid = a->ring_nr;
           m->m_pkthdr.rcvif = ifp; /* used for tx notification */
           CURVNET_SET(ifp->if_vnet);
           ret = NA(ifp)->if_transmit(ifp, m);
           CURVNET_RESTORE();
           return ret ? -1 : 0;
   }
   
   
   struct netmap_adapter *
   netmap_getna(if_t ifp)
   {
           return (NA((struct ifnet *)ifp));
   }
   
   /*
    * The following two functions are empty until we have a generic
    * way to extract the info from the ifp
    */
   int
   nm_os_generic_find_num_desc(struct ifnet *ifp, unsigned int *tx, unsigned int *rx)
   {
           return 0;
   }
   
   
   void
   nm_os_generic_find_num_queues(struct ifnet *ifp, u_int *txq, u_int *rxq)
   {
           unsigned num_rings = netmap_generic_rings ? netmap_generic_rings : 1;
   
           *txq = num_rings;
           *rxq = num_rings;
   }
   
   void
   nm_os_generic_set_features(struct netmap_generic_adapter *gna)
   {
   
           gna->rxsg = 1; /* Supported through m_copydata. */
           gna->txqdisc = 0; /* Not supported. */
   }
   
   void
   nm_os_mitigation_init(struct nm_generic_mit *mit, int idx, struct netmap_adapter *na)
   {
           mit->mit_pending = 0;
           mit->mit_ring_idx = idx;
           mit->mit_na = na;
   }
   
   
   void
   nm_os_mitigation_start(struct nm_generic_mit *mit)
   {
   }
   
   
   void
   nm_os_mitigation_restart(struct nm_generic_mit *mit)
   {
   }
   
   
   int
   nm_os_mitigation_active(struct nm_generic_mit *mit)
   {
   
           return 0;
   }
   
   
   void
   nm_os_mitigation_cleanup(struct nm_generic_mit *mit)
   {
   }
   
   static int
   nm_vi_dummy(struct ifnet *ifp, u_long cmd, caddr_t addr)
   {
   
           return EINVAL;
   }
   
   static void
   nm_vi_start(struct ifnet *ifp)
   {
           panic("nm_vi_start() must not be called");
   }
   
   /*
    * Index manager of persistent virtual interfaces.
    * It is used to decide the lowest byte of the MAC address.
    * We use the same algorithm with management of bridge port index.
    */
   #define NM_VI_MAX       255
   static struct {
           uint8_t index[NM_VI_MAX]; /* XXX just for a reasonable number */
           uint8_t active;
           struct mtx lock;
   } nm_vi_indices;
   
   void
   nm_os_vi_init_index(void)
   {
           int i;
           for (i = 0; i < NM_VI_MAX; i++)
                   nm_vi_indices.index[i] = i;
           nm_vi_indices.active = 0;
           mtx_init(&nm_vi_indices.lock, "nm_vi_indices_lock", NULL, MTX_DEF);
   }
   
   /* return -1 if no index available */
   static int
   nm_vi_get_index(void)
   {
           int ret;
   
           mtx_lock(&nm_vi_indices.lock);
           ret = nm_vi_indices.active == NM_VI_MAX ? -1 :
                   nm_vi_indices.index[nm_vi_indices.active++];
           mtx_unlock(&nm_vi_indices.lock);
           return ret;
   }
   
   static void
   nm_vi_free_index(uint8_t val)
   {
           int i, lim;
   
           mtx_lock(&nm_vi_indices.lock);
           lim = nm_vi_indices.active;
           for (i = 0; i < lim; i++) {
                   if (nm_vi_indices.index[i] == val) {
                           /* swap index[lim-1] and j */
                           int tmp = nm_vi_indices.index[lim-1];
                           nm_vi_indices.index[lim-1] = val;
                           nm_vi_indices.index[i] = tmp;
                           nm_vi_indices.active--;
                           break;
                   }
           }
           if (lim == nm_vi_indices.active)
                   nm_prerr("Index %u not found", val);
           mtx_unlock(&nm_vi_indices.lock);
   }
   #undef NM_VI_MAX
   
   /*
    * Implementation of a netmap-capable virtual interface that
    * registered to the system.
    * It is based on if_tap.c and ip_fw_log.c in FreeBSD 9.
    *
    * Note: Linux sets refcount to 0 on allocation of net_device,
    * then increments it on registration to the system.
    * FreeBSD sets refcount to 1 on if_alloc(), and does not
    * increment this refcount on if_attach().
    */
   int
   nm_os_vi_persist(const char *name, struct ifnet **ret)
   {
           struct ifnet *ifp;
           u_short macaddr_hi;
           uint32_t macaddr_mid;
           u_char eaddr[6];
           int unit = nm_vi_get_index(); /* just to decide MAC address */
   
           if (unit < 0)
                   return EBUSY;
           /*
            * We use the same MAC address generation method with tap
            * except for the highest octet is 00:be instead of 00:bd
            */
           macaddr_hi = htons(0x00be); /* XXX tap + 1 */
           macaddr_mid = (uint32_t) ticks;
           bcopy(&macaddr_hi, eaddr, sizeof(short));
           bcopy(&macaddr_mid, &eaddr[2], sizeof(uint32_t));
           eaddr[5] = (uint8_t)unit;
   
           ifp = if_alloc(IFT_ETHER);
           if (ifp == NULL) {
                   nm_prerr("if_alloc failed");
                   return ENOMEM;
           }
           if_initname(ifp, name, IF_DUNIT_NONE);
           ifp->if_mtu = 65536;
           ifp->if_flags = IFF_UP | IFF_SIMPLEX | IFF_MULTICAST;
           ifp->if_init = (void *)nm_vi_dummy;
           ifp->if_ioctl = nm_vi_dummy;
           ifp->if_start = nm_vi_start;
           ifp->if_mtu = ETHERMTU;
           IFQ_SET_MAXLEN(&ifp->if_snd, ifqmaxlen);
           ifp->if_capabilities |= IFCAP_LINKSTATE;
           ifp->if_capenable |= IFCAP_LINKSTATE;
   
           ether_ifattach(ifp, eaddr);
           *ret = ifp;
           return 0;
   }
   
   /* unregister from the system and drop the final refcount */
   void
   nm_os_vi_detach(struct ifnet *ifp)
   {
           nm_vi_free_index(((char *)IF_LLADDR(ifp))[5]);
           ether_ifdetach(ifp);
           if_free(ifp);
   }
   
   #ifdef WITH_EXTMEM
   #include <vm/vm_map.h>
   #include <vm/vm_extern.h>
   #include <vm/vm_kern.h>
   struct nm_os_extmem {
           vm_object_t obj;
           vm_offset_t kva;
           vm_offset_t size;
           uintptr_t scan;
   };
   
   void
   nm_os_extmem_delete(struct nm_os_extmem *e)
   {
           nm_prinf("freeing %zx bytes", (size_t)e->size);
           vm_map_remove(kernel_map, e->kva, e->kva + e->size);
           nm_os_free(e);
   }
   
   char *
   nm_os_extmem_nextpage(struct nm_os_extmem *e)
   {
           char *rv = NULL;
           if (e->scan < e->kva + e->size) {
                   rv = (char *)e->scan;
                   e->scan += PAGE_SIZE;
           }
           return rv;
   }
   
   int
   nm_os_extmem_isequal(struct nm_os_extmem *e1, struct nm_os_extmem *e2)
   {
           return (e1->obj == e2->obj);
   }
   
   int
   nm_os_extmem_nr_pages(struct nm_os_extmem *e)
   {
           return e->size >> PAGE_SHIFT;
   }
   
   struct nm_os_extmem *
   nm_os_extmem_create(unsigned long p, struct nmreq_pools_info *pi, int *perror)
   {
           vm_map_t map;
           vm_map_entry_t entry;
           vm_object_t obj;
           vm_prot_t prot;
           vm_pindex_t index;
           boolean_t wired;
           struct nm_os_extmem *e = NULL;
           int rv, error = 0;
   
           e = nm_os_malloc(sizeof(*e));
           if (e == NULL) {
                   error = ENOMEM;
                   goto out;
           }
   
           map = &curthread->td_proc->p_vmspace->vm_map;
           rv = vm_map_lookup(&map, p, VM_PROT_RW, &entry,
                           &obj, &index, &prot, &wired);
           if (rv != KERN_SUCCESS) {
                   nm_prerr("address %lx not found", p);
                   error = vm_mmap_to_errno(rv);
                   goto out_free;
           }
           vm_object_reference(obj);
   
           /* check that we are given the whole vm_object ? */
           vm_map_lookup_done(map, entry);
   
           e->obj = obj;
           /* Wire the memory and add the vm_object to the kernel map,
            * to make sure that it is not freed even if all the processes
            * that are mmap()ing should munmap() it.
            */
           e->kva = vm_map_min(kernel_map);
           e->size = obj->size << PAGE_SHIFT;
           rv = vm_map_find(kernel_map, obj, 0, &e->kva, e->size, 0,
                           VMFS_OPTIMAL_SPACE, VM_PROT_READ | VM_PROT_WRITE,
                           VM_PROT_READ | VM_PROT_WRITE, 0);
           if (rv != KERN_SUCCESS) {
                   nm_prerr("vm_map_find(%zx) failed", (size_t)e->size);
                   error = vm_mmap_to_errno(rv);
                   goto out_rel;
           }
           rv = vm_map_wire(kernel_map, e->kva, e->kva + e->size,
                           VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
           if (rv != KERN_SUCCESS) {
                   nm_prerr("vm_map_wire failed");
                   error = vm_mmap_to_errno(rv);
                   goto out_rem;
           }
   
           e->scan = e->kva;
   
           return e;
   
   out_rem:
           vm_map_remove(kernel_map, e->kva, e->kva + e->size);
   out_rel:
           vm_object_deallocate(e->obj);
           e->obj = NULL;
   out_free:
           nm_os_free(e);
   out:
           if (perror)
                   *perror = error;
           return NULL;
   }
   #endif /* WITH_EXTMEM */
   
   /* ================== PTNETMAP GUEST SUPPORT ==================== */
   
   #ifdef WITH_PTNETMAP
   #include <sys/bus.h>
   #include <sys/rman.h>
   #include <machine/bus.h>        /* bus_dmamap_* */
   #include <machine/resource.h>
   #include <dev/pci/pcivar.h>
   #include <dev/pci/pcireg.h>
   /*
    * ptnetmap memory device (memdev) for freebsd guest,
    * ssed to expose host netmap memory to the guest through a PCI BAR.
    */
   
   /*
    * ptnetmap memdev private data structure
    */
   struct ptnetmap_memdev {
           device_t dev;
           struct resource *pci_io;
           struct resource *pci_mem;
           struct netmap_mem_d *nm_mem;
   };
   
   static int      ptn_memdev_probe(device_t);
   static int      ptn_memdev_attach(device_t);
   static int      ptn_memdev_detach(device_t);
   static int      ptn_memdev_shutdown(device_t);
   
   static device_method_t ptn_memdev_methods[] = {
           DEVMETHOD(device_probe, ptn_memdev_probe),
           DEVMETHOD(device_attach, ptn_memdev_attach),
           DEVMETHOD(device_detach, ptn_memdev_detach),
           DEVMETHOD(device_shutdown, ptn_memdev_shutdown),
           DEVMETHOD_END
   };
   
   static driver_t ptn_memdev_driver = {
           PTNETMAP_MEMDEV_NAME,
           ptn_memdev_methods,
           sizeof(struct ptnetmap_memdev),
   };
   
   /* We use (SI_ORDER_MIDDLE+1) here, see DEV_MODULE_ORDERED() invocation
    * below. */
   DRIVER_MODULE_ORDERED(ptn_memdev, pci, ptn_memdev_driver, NULL, NULL,
                         SI_ORDER_MIDDLE + 1);
   
   /*
    * Map host netmap memory through PCI-BAR in the guest OS,
    * returning physical (nm_paddr) and virtual (nm_addr) addresses
    * of the netmap memory mapped in the guest.
    */
   int
   nm_os_pt_memdev_iomap(struct ptnetmap_memdev *ptn_dev, vm_paddr_t *nm_paddr,
                         void **nm_addr, uint64_t *mem_size)
   {
           int rid;
   
           nm_prinf("ptn_memdev_driver iomap");
   
           rid = PCIR_BAR(PTNETMAP_MEM_PCI_BAR);
           *mem_size = bus_read_4(ptn_dev->pci_io, PTNET_MDEV_IO_MEMSIZE_HI);
           *mem_size = bus_read_4(ptn_dev->pci_io, PTNET_MDEV_IO_MEMSIZE_LO) |
                           (*mem_size << 32);
   
           /* map memory allocator */
           ptn_dev->pci_mem = bus_alloc_resource(ptn_dev->dev, SYS_RES_MEMORY,
                           &rid, 0, ~0, *mem_size, RF_ACTIVE);
           if (ptn_dev->pci_mem == NULL) {
                   *nm_paddr = 0;
                   *nm_addr = NULL;
                   return ENOMEM;
           }
   
           *nm_paddr = rman_get_start(ptn_dev->pci_mem);
           *nm_addr = rman_get_virtual(ptn_dev->pci_mem);
   
           nm_prinf("=== BAR %d start %lx len %lx mem_size %lx ===",
                           PTNETMAP_MEM_PCI_BAR,
                           (unsigned long)(*nm_paddr),
                           (unsigned long)rman_get_size(ptn_dev->pci_mem),
                           (unsigned long)*mem_size);
           return (0);
   }
   
   uint32_t
   nm_os_pt_memdev_ioread(struct ptnetmap_memdev *ptn_dev, unsigned int reg)
   {
           return bus_read_4(ptn_dev->pci_io, reg);
   }
   
   /* Unmap host netmap memory. */
   void
   nm_os_pt_memdev_iounmap(struct ptnetmap_memdev *ptn_dev)
   {
           nm_prinf("ptn_memdev_driver iounmap");
   
           if (ptn_dev->pci_mem) {
                   bus_release_resource(ptn_dev->dev, SYS_RES_MEMORY,
                           PCIR_BAR(PTNETMAP_MEM_PCI_BAR), ptn_dev->pci_mem);
                   ptn_dev->pci_mem = NULL;
           }
   }
   
   /* Device identification routine, return BUS_PROBE_DEFAULT on success,
    * positive on failure */
   static int
   ptn_memdev_probe(device_t dev)
   {
           char desc[256];
   
           if (pci_get_vendor(dev) != PTNETMAP_PCI_VENDOR_ID)
                   return (ENXIO);
           if (pci_get_device(dev) != PTNETMAP_PCI_DEVICE_ID)
                   return (ENXIO);
   
           snprintf(desc, sizeof(desc), "%s PCI adapter",
                           PTNETMAP_MEMDEV_NAME);
           device_set_desc_copy(dev, desc);
   
           return (BUS_PROBE_DEFAULT);
   }
   
   /* Device initialization routine. */
   static int
   ptn_memdev_attach(device_t dev)
   {
           struct ptnetmap_memdev *ptn_dev;
           int rid;
           uint16_t mem_id;
   
           ptn_dev = device_get_softc(dev);
           ptn_dev->dev = dev;
   
           pci_enable_busmaster(dev);
   
           rid = PCIR_BAR(PTNETMAP_IO_PCI_BAR);
           ptn_dev->pci_io = bus_alloc_resource_any(dev, SYS_RES_IOPORT, &rid,
                                                    RF_ACTIVE);
           if (ptn_dev->pci_io == NULL) {
                   device_printf(dev, "cannot map I/O space\n");
                   return (ENXIO);
           }
   
           mem_id = bus_read_4(ptn_dev->pci_io, PTNET_MDEV_IO_MEMID);
   
           /* create guest allocator */
           ptn_dev->nm_mem = netmap_mem_pt_guest_attach(ptn_dev, mem_id);
           if (ptn_dev->nm_mem == NULL) {
                   ptn_memdev_detach(dev);
                   return (ENOMEM);
           }
           netmap_mem_get(ptn_dev->nm_mem);
   
           nm_prinf("ptnetmap memdev attached, host memid: %u", mem_id);
   
           return (0);
   }
   
   /* Device removal routine. */
   static int
   ptn_memdev_detach(device_t dev)
   {
           struct ptnetmap_memdev *ptn_dev;
   
           ptn_dev = device_get_softc(dev);
   
           if (ptn_dev->nm_mem) {
                   nm_prinf("ptnetmap memdev detached, host memid %u",
                           netmap_mem_get_id(ptn_dev->nm_mem));
                   netmap_mem_put(ptn_dev->nm_mem);
                   ptn_dev->nm_mem = NULL;
           }
           if (ptn_dev->pci_mem) {
                   bus_release_resource(dev, SYS_RES_MEMORY,
                           PCIR_BAR(PTNETMAP_MEM_PCI_BAR), ptn_dev->pci_mem);
                   ptn_dev->pci_mem = NULL;
           }
           if (ptn_dev->pci_io) {
                   bus_release_resource(dev, SYS_RES_IOPORT,
                           PCIR_BAR(PTNETMAP_IO_PCI_BAR), ptn_dev->pci_io);
                   ptn_dev->pci_io = NULL;
           }
   
           return (0);
   }
   
   static int
   ptn_memdev_shutdown(device_t dev)
   {
           return bus_generic_shutdown(dev);
   }
   
   #endif /* WITH_PTNETMAP */
   
   /*
    * In order to track whether pages are still mapped, we hook into
    * the standard cdev_pager and intercept the constructor and
    * destructor.
    */
   
   struct netmap_vm_handle_t {
           struct cdev             *dev;
           struct netmap_priv_d    *priv;
   };
   
   
   static int
   netmap_dev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
                   vm_ooffset_t foff, struct ucred *cred, u_short *color)
   {
           struct netmap_vm_handle_t *vmh = handle;
   
           if (netmap_verbose)
                   nm_prinf("handle %p size %jd prot %d foff %jd",
                           handle, (intmax_t)size, prot, (intmax_t)foff);
           if (color)
                   *color = 0;
           dev_ref(vmh->dev);
           return 0;
   }
   
   
   static void
   netmap_dev_pager_dtor(void *handle)
   {
           struct netmap_vm_handle_t *vmh = handle;
           struct cdev *dev = vmh->dev;
           struct netmap_priv_d *priv = vmh->priv;
   
           if (netmap_verbose)
                   nm_prinf("handle %p", handle);
           netmap_dtor(priv);
           free(vmh, M_DEVBUF);
           dev_rel(dev);
   }
   
   
  static int
  netmap_dev_pager_fault(vm_object_t object, vm_ooffset_t offset,
          int prot, vm_page_t *mres)
  {
          struct netmap_vm_handle_t *vmh = object->handle;
          struct netmap_priv_d *priv = vmh->priv;
          struct netmap_adapter *na = priv->np_na;
          vm_paddr_t paddr;
          vm_page_t page;
          vm_memattr_t memattr;
  
          nm_prdis("object %p offset %jd prot %d mres %p",
                          object, (intmax_t)offset, prot, mres);
          memattr = object->memattr;
          paddr = netmap_mem_ofstophys(na->nm_mem, offset);
          if (paddr == 0)
                  return VM_PAGER_FAIL;
  
          if (((*mres)->flags & PG_FICTITIOUS) != 0) {
                  /*
                   * If the passed in result page is a fake page, update it with
                   * the new physical address.
                   */
                  page = *mres;
                  vm_page_updatefake(page, paddr, memattr);
          } else {
                  /*
                   * Replace the passed in reqpage page with our own fake page and
                   * free up the all of the original pages.
                   */
  #ifndef VM_OBJECT_WUNLOCK       /* FreeBSD < 10.x */
  #define VM_OBJECT_WUNLOCK VM_OBJECT_UNLOCK
  #define VM_OBJECT_WLOCK VM_OBJECT_LOCK
  #endif /* VM_OBJECT_WUNLOCK */
  
                  VM_OBJECT_WUNLOCK(object);
                  page = vm_page_getfake(paddr, memattr);
                  VM_OBJECT_WLOCK(object);
                  vm_page_replace(page, object, (*mres)->pindex, *mres);
                  *mres = page;
          }
          page->valid = VM_PAGE_BITS_ALL;
          return (VM_PAGER_OK);
  }
  
  
  static struct cdev_pager_ops netmap_cdev_pager_ops = {
          .cdev_pg_ctor = netmap_dev_pager_ctor,
          .cdev_pg_dtor = netmap_dev_pager_dtor,
          .cdev_pg_fault = netmap_dev_pager_fault,
  };
  
  
  static int
  netmap_mmap_single(struct cdev *cdev, vm_ooffset_t *foff,
          vm_size_t objsize,  vm_object_t *objp, int prot)
  {
          int error;
          struct netmap_vm_handle_t *vmh;
          struct netmap_priv_d *priv;
          vm_object_t obj;
  
          if (netmap_verbose)
                  nm_prinf("cdev %p foff %jd size %jd objp %p prot %d", cdev,
                      (intmax_t )*foff, (intmax_t )objsize, objp, prot);
  
          vmh = malloc(sizeof(struct netmap_vm_handle_t), M_DEVBUF,
                                M_NOWAIT | M_ZERO);
          if (vmh == NULL)
                  return ENOMEM;
          vmh->dev = cdev;
  
          NMG_LOCK();
          error = devfs_get_cdevpriv((void**)&priv);
          if (error)
                  goto err_unlock;
          if (priv->np_nifp == NULL) {
                  error = EINVAL;
                  goto err_unlock;
          }
          vmh->priv = priv;
          priv->np_refs++;
          NMG_UNLOCK();
  
          obj = cdev_pager_allocate(vmh, OBJT_DEVICE,
                  &netmap_cdev_pager_ops, objsize, prot,
                  *foff, NULL);
          if (obj == NULL) {
                  nm_prerr("cdev_pager_allocate failed");
                  error = EINVAL;
                  goto err_deref;
          }
  
          *objp = obj;
          return 0;
  
  err_deref:
          NMG_LOCK();
          priv->np_refs--;
  err_unlock:
          NMG_UNLOCK();
  // err:
          free(vmh, M_DEVBUF);
          return error;
  }
  
  /*
   * On FreeBSD the close routine is only called on the last close on
   * the device (/dev/netmap) so we cannot do anything useful.
   * To track close() on individual file descriptors we pass netmap_dtor() to
   * devfs_set_cdevpriv() on open(). The FreeBSD kernel will call the destructor
   * when the last fd pointing to the device is closed.
   *
   * Note that FreeBSD does not even munmap() on close() so we also have
   * to track mmap() ourselves, and postpone the call to
   * netmap_dtor() is called when the process has no open fds and no active
   * memory maps on /dev/netmap, as in linux.
   */
  static int
  netmap_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
  {
          if (netmap_verbose)
                  nm_prinf("dev %p fflag 0x%x devtype %d td %p",
                          dev, fflag, devtype, td);
          return 0;
  }
  
  
  static int
  netmap_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
  {
          struct netmap_priv_d *priv;
          int error;
  
          (void)dev;
          (void)oflags;
          (void)devtype;
          (void)td;
  
          NMG_LOCK();
          priv = netmap_priv_new();
          if (priv == NULL) {
                  error = ENOMEM;
                  goto out;
          }
          error = devfs_set_cdevpriv(priv, netmap_dtor);
          if (error) {
                  netmap_priv_delete(priv);
          }
  out:
          NMG_UNLOCK();
          return error;
  }
  
  /******************** kthread wrapper ****************/
  #include <sys/sysproto.h>
  u_int
  nm_os_ncpus(void)
  {
          return mp_maxid + 1;
  }
  
  struct nm_kctx_ctx {
          /* Userspace thread (kthread creator). */
          struct thread *user_td;
  
          /* worker function and parameter */
          nm_kctx_worker_fn_t worker_fn;
          void *worker_private;
  
          struct nm_kctx *nmk;
  
          /* integer to manage multiple worker contexts (e.g., RX or TX on ptnetmap) */
          long type;
  };
  
  struct nm_kctx {
          struct thread *worker;
          struct mtx worker_lock;
          struct nm_kctx_ctx worker_ctx;
          int run;                        /* used to stop kthread */
          int attach_user;                /* kthread attached to user_process */
          int affinity;
  };
  
  static void
  nm_kctx_worker(void *data)
  {
          struct nm_kctx *nmk = data;
          struct nm_kctx_ctx *ctx = &nmk->worker_ctx;
  
          if (nmk->affinity >= 0) {
                  thread_lock(curthread);
                  sched_bind(curthread, nmk->affinity);
                  thread_unlock(curthread);
          }
  
          while (nmk->run) {
                  /*
                   * check if the parent process dies
                   * (when kthread is attached to user process)
                   */
                  if (ctx->user_td) {
                          PROC_LOCK(curproc);
                          thread_suspend_check(0);
                          PROC_UNLOCK(curproc);
                  } else {
                          kthread_suspend_check();
                  }
  
                  /* Continuously execute worker process. */
                  ctx->worker_fn(ctx->worker_private); /* worker body */
          }
  
          kthread_exit();
  }
  
  void
  nm_os_kctx_worker_setaff(struct nm_kctx *nmk, int affinity)
  {
          nmk->affinity = affinity;
  }
  
  struct nm_kctx *
  nm_os_kctx_create(struct nm_kctx_cfg *cfg, void *opaque)
  {
          struct nm_kctx *nmk = NULL;
  
          nmk = malloc(sizeof(*nmk),  M_DEVBUF, M_NOWAIT | M_ZERO);
          if (!nmk)
                  return NULL;
  
          mtx_init(&nmk->worker_lock, "nm_kthread lock", NULL, MTX_DEF);
          nmk->worker_ctx.worker_fn = cfg->worker_fn;
          nmk->worker_ctx.worker_private = cfg->worker_private;
          nmk->worker_ctx.type = cfg->type;
          nmk->affinity = -1;
  
          /* attach kthread to user process (ptnetmap) */
          nmk->attach_user = cfg->attach_user;
  
          return nmk;
  }
  
  int
  nm_os_kctx_worker_start(struct nm_kctx *nmk)
  {
          struct proc *p = NULL;
          int error = 0;
  
          /* Temporarily disable this function as it is currently broken
           * and causes kernel crashes. The failure can be triggered by
           * the "vale_polling_enable_disable" test in ctrl-api-test.c. */
          return EOPNOTSUPP;
  
          if (nmk->worker)
                  return EBUSY;
  
          /* check if we want to attach kthread to user process */
          if (nmk->attach_user) {
                  nmk->worker_ctx.user_td = curthread;
                  p = curthread->td_proc;
          }
  
          /* enable kthread main loop */
          nmk->run = 1;
          /* create kthread */
          if((error = kthread_add(nm_kctx_worker, nmk, p,
                          &nmk->worker, RFNOWAIT /* to be checked */, 0, "nm-kthread-%ld",
                          nmk->worker_ctx.type))) {
                  goto err;
          }
  
          nm_prinf("nm_kthread started td %p", nmk->worker);
  
          return 0;
  err:
          nm_prerr("nm_kthread start failed err %d", error);
          nmk->worker = NULL;
          return error;
  }
  
  void
  nm_os_kctx_worker_stop(struct nm_kctx *nmk)
  {
          if (!nmk->worker)
                  return;
  
          /* tell to kthread to exit from main loop */
          nmk->run = 0;
  
          /* wake up kthread if it sleeps */
          kthread_resume(nmk->worker);
  
          nmk->worker = NULL;
  }
  
  void
  nm_os_kctx_destroy(struct nm_kctx *nmk)
  {
          if (!nmk)
                  return;
  
          if (nmk->worker)
                  nm_os_kctx_worker_stop(nmk);
  
          free(nmk, M_DEVBUF);
  }
  
  /******************** kqueue support ****************/
  
  /*
   * In addition to calling selwakeuppri(), nm_os_selwakeup() also
   * needs to call knote() to wake up kqueue listeners.
   * This operation is deferred to a taskqueue in order to avoid possible
   * lock order reversals; these may happen because knote() grabs a
   * private lock associated to the 'si' (see struct selinfo,
   * struct nm_selinfo, and nm_os_selinfo_init), and nm_os_selwakeup()
   * can be called while holding the lock associated to a different
   * 'si'.
   * When calling knote() we use a non-zero 'hint' argument to inform
   * the netmap_knrw() function that it is being called from
   * 'nm_os_selwakeup'; this is necessary because when netmap_knrw() is
   * called by the kevent subsystem (i.e. kevent_scan()) we also need to
   * call netmap_poll().
   *
   * The netmap_kqfilter() function registers one or another f_event
   * depending on read or write mode. A pointer to the struct
   * 'netmap_priv_d' is stored into kn->kn_hook, so that it can later
   * be passed to netmap_poll(). We pass NULL as a third argument to
   * netmap_poll(), so that the latter only runs the txsync/rxsync
   * (if necessary), and skips the nm_os_selrecord() calls.
   */
  
  
  void
  nm_os_selwakeup(struct nm_selinfo *si)
  {
          selwakeuppri(&si->si, PI_NET);
          if (si->kqueue_users > 0) {
                  taskqueue_enqueue(si->ntfytq, &si->ntfytask);
          }
  }
  
  void
  nm_os_selrecord(struct thread *td, struct nm_selinfo *si)
  {
          selrecord(td, &si->si);
  }
  
  static void
  netmap_knrdetach(struct knote *kn)
  {
          struct netmap_priv_d *priv = (struct netmap_priv_d *)kn->kn_hook;
          struct nm_selinfo *si = priv->np_si[NR_RX];
  
          knlist_remove(&si->si.si_note, kn, /*islocked=*/0);
          NMG_LOCK();
          KASSERT(si->kqueue_users > 0, ("kqueue_user underflow on %s",
              si->mtxname));
          si->kqueue_users--;
          nm_prinf("kqueue users for %s: %d", si->mtxname, si->kqueue_users);
          NMG_UNLOCK();
  }
  
  static void
  netmap_knwdetach(struct knote *kn)
  {
          struct netmap_priv_d *priv = (struct netmap_priv_d *)kn->kn_hook;
          struct nm_selinfo *si = priv->np_si[NR_TX];
  
          knlist_remove(&si->si.si_note, kn, /*islocked=*/0);
          NMG_LOCK();
          si->kqueue_users--;
          nm_prinf("kqueue users for %s: %d", si->mtxname, si->kqueue_users);
          NMG_UNLOCK();
  }
  
  /*
   * Callback triggered by netmap notifications (see netmap_notify()),
   * and by the application calling kevent(). In the former case we
   * just return 1 (events ready), since we are not able to do better.
   * In the latter case we use netmap_poll() to see which events are
   * ready.
   */
  static int
  netmap_knrw(struct knote *kn, long hint, int events)
  {
          struct netmap_priv_d *priv;
          int revents;
  
          if (hint != 0) {
                  /* Called from netmap_notify(), typically from a
                   * thread different from the one issuing kevent().
                   * Assume we are ready. */
                  return 1;
          }
  
          /* Called from kevent(). */
          priv = kn->kn_hook;
          revents = netmap_poll(priv, events, /*thread=*/NULL);
  
          return (events & revents) ? 1 : 0;
  }
  
  static int
  netmap_knread(struct knote *kn, long hint)
  {
          return netmap_knrw(kn, hint, POLLIN);
  }
  
  static int
  netmap_knwrite(struct knote *kn, long hint)
  {
          return netmap_knrw(kn, hint, POLLOUT);
  }
  
  static struct filterops netmap_rfiltops = {
          .f_isfd = 1,
          .f_detach = netmap_knrdetach,
          .f_event = netmap_knread,
  };
  
  static struct filterops netmap_wfiltops = {
          .f_isfd = 1,
          .f_detach = netmap_knwdetach,
          .f_event = netmap_knwrite,
  };
  
  
  /*
   * This is called when a thread invokes kevent() to record
   * a change in the configuration of the kqueue().
   * The 'priv' is the one associated to the open netmap device.
   */
  static int
  netmap_kqfilter(struct cdev *dev, struct knote *kn)
  {
          struct netmap_priv_d *priv;
          int error;
          struct netmap_adapter *na;
          struct nm_selinfo *si;
          int ev = kn->kn_filter;
  
          if (ev != EVFILT_READ && ev != EVFILT_WRITE) {
                  nm_prerr("bad filter request %d", ev);
                  return 1;
          }
          error = devfs_get_cdevpriv((void**)&priv);
          if (error) {
                  nm_prerr("device not yet setup");
                  return 1;
          }
          na = priv->np_na;
          if (na == NULL) {
                  nm_prerr("no netmap adapter for this file descriptor");
                  return 1;
          }
          /* the si is indicated in the priv */
          si = priv->np_si[(ev == EVFILT_WRITE) ? NR_TX : NR_RX];
          kn->kn_fop = (ev == EVFILT_WRITE) ?
                  &netmap_wfiltops : &netmap_rfiltops;
          kn->kn_hook = priv;
          NMG_LOCK();
          si->kqueue_users++;
          nm_prinf("kqueue users for %s: %d", si->mtxname, si->kqueue_users);
          NMG_UNLOCK();
          knlist_add(&si->si.si_note, kn, /*islocked=*/0);
  
          return 0;
  }
  
  static int
  freebsd_netmap_poll(struct cdev *cdevi __unused, int events, struct thread *td)
  {
          struct netmap_priv_d *priv;
          if (devfs_get_cdevpriv((void **)&priv)) {
                  return POLLERR;
          }
          return netmap_poll(priv, events, td);
  }
  
  static int
  freebsd_netmap_ioctl(struct cdev *dev __unused, u_long cmd, caddr_t data,
                  int ffla __unused, struct thread *td)
  {
          int error;
          struct netmap_priv_d *priv;
  
          CURVNET_SET(TD_TO_VNET(td));
          error = devfs_get_cdevpriv((void **)&priv);
          if (error) {
                  /* XXX ENOENT should be impossible, since the priv
                   * is now created in the open */
                  if (error == ENOENT)
                          error = ENXIO;
                  goto out;
          }
          error = netmap_ioctl(priv, cmd, data, td, /*nr_body_is_user=*/1);
  out:
          CURVNET_RESTORE();
  
          return error;
  }
  
  void
  nm_os_onattach(struct ifnet *ifp)
  {
          ifp->if_capabilities |= IFCAP_NETMAP;
  }
  
  void
  nm_os_onenter(struct ifnet *ifp)
  {
          struct netmap_adapter *na = NA(ifp);
  
          na->if_transmit = ifp->if_transmit;
          ifp->if_transmit = netmap_transmit;
          ifp->if_capenable |= IFCAP_NETMAP;
  }
  
  void
  nm_os_onexit(struct ifnet *ifp)
  {
          struct netmap_adapter *na = NA(ifp);
  
          ifp->if_transmit = na->if_transmit;
          ifp->if_capenable &= ~IFCAP_NETMAP;
  }
  
  extern struct cdevsw netmap_cdevsw; /* XXX used in netmap.c, should go elsewhere */
  struct cdevsw netmap_cdevsw = {
          .d_version = D_VERSION,
          .d_name = "netmap",
          .d_open = netmap_open,
          .d_mmap_single = netmap_mmap_single,
          .d_ioctl = freebsd_netmap_ioctl,
          .d_poll = freebsd_netmap_poll,
          .d_kqfilter = netmap_kqfilter,
          .d_close = netmap_close,
  };
  /*--- end of kqueue support ----*/
  
  /*
   * Kernel entry point.
   *
   * Initialize/finalize the module and return.
   *
   * Return 0 on success, errno on failure.
   */
  static int
  netmap_loader(__unused struct module *module, int event, __unused void *arg)
  {
          int error = 0;
  
          switch (event) {
          case MOD_LOAD:
                  error = netmap_init();
                  break;
  
          case MOD_UNLOAD:
                  /*
                   * if some one is still using netmap,
                   * then the module can not be unloaded.
                   */
                  if (netmap_use_count) {
                          nm_prerr("netmap module can not be unloaded - netmap_use_count: %d",
                                          netmap_use_count);
                          error = EBUSY;
                          break;
                  }
                  netmap_fini();
                  break;
  
          default:
                  error = EOPNOTSUPP;
                  break;
          }
  
          return (error);
  }
  
  #ifdef DEV_MODULE_ORDERED
  /*
   * The netmap module contains three drivers: (i) the netmap character device
   * driver; (ii) the ptnetmap memdev PCI device driver, (iii) the ptnet PCI
   * device driver. The attach() routines of both (ii) and (iii) need the
   * lock of the global allocator, and such lock is initialized in netmap_init(),
   * which is part of (i).
   * Therefore, we make sure that (i) is loaded before (ii) and (iii), using
   * the 'order' parameter of driver declaration macros. For (i), we specify
   * SI_ORDER_MIDDLE, while higher orders are used with the DRIVER_MODULE_ORDERED
   * macros for (ii) and (iii).
   */
  DEV_MODULE_ORDERED(netmap, netmap_loader, NULL, SI_ORDER_MIDDLE);
  #else /* !DEV_MODULE_ORDERED */
  DEV_MODULE(netmap, netmap_loader, NULL);
  #endif /* DEV_MODULE_ORDERED  */
  MODULE_DEPEND(netmap, pci, 1, 1, 1);
  MODULE_VERSION(netmap, 1);
  /* reduce conditional code */
  // linux API, use for the knlist in FreeBSD
  /* use a private mutex for the knlist */

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