em0 hangs on 8-STABLE again

[Lev Serebryakov]

Hello, Freebsd-net.

  My home server lost connection on em0 this night again. It was
persistent problem some times ago, but with version 7.2.3 it is first
time, but with worse symptoms.

  It looks like undetected hardware hang-up: no packets could be sent
or received, and no any output in dmesg or log files. Interface
up/down with ifconfig and cable unplugging doesn't help: ifaces sees
all these changes, but no packets could be sent/received anyway. I
was forced to reboot server to make it work again.

  IT is rather old 8-STABLE (Oct 2011), but it sems, that last change
in e1000 for 8-STABLE was r223675, in Jun 2011, so it is "fresh"
sources (I don't believe, that r229147 is related).

 Output of `sysctl dev.em' when card is not working (but after some up/down
events) is attached.

 NIC is:

em0: <Intel(R) PRO/1000 Network Connection 7.2.3> port 0xd880-0xd89f mem 0xfea40000-0xfea5ffff,0xfea7a000-0xfea7afff irq 20 at device 25.0 on pci0
em0: Using an MSI interrupt
em0: [FILTER]
em0: Ethernet address: 00:1e:8c:75:03:0d

em0 at pci0:0:25:0:        class=0x020000 card=0x82681043 chip=0x10bd8086 rev=0x02 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = 'Intel 82566DM Gigabit Ethernet Adapter (82566DM)'
    class      = network
    subclass   = ethernet



-- 
// Black Lion AKA Lev Serebryakov <lev at FreeBSD.org>
-------------- next part --------------
dev.em.0.%desc: Intel(R) PRO/1000 Network Connection 7.2.3
dev.em.0.%driver: em
dev.em.0.%location: slot=25 function=0 handle=\_SB_.PCI0.GBEC
dev.em.0.%pnpinfo: vendor=0x8086 device=0x10bd subvendor=0x1043 subdevice=0x8268 class=0x020000
dev.em.0.%parent: pci0
dev.em.0.nvm: -1
dev.em.0.debug: -1
dev.em.0.rx_int_delay: 0
dev.em.0.tx_int_delay: 66
dev.em.0.rx_abs_int_delay: 66
dev.em.0.tx_abs_int_delay: 66
dev.em.0.rx_processing_limit: 100
dev.em.0.flow_control: 3
dev.em.0.eee_control: 0
dev.em.0.link_irq: 0
dev.em.0.mbuf_alloc_fail: 0
dev.em.0.cluster_alloc_fail: 0
dev.em.0.dropped: 0
dev.em.0.tx_dma_fail: 0
dev.em.0.rx_overruns: 7742
dev.em.0.watchdog_timeouts: 0
dev.em.0.device_control: 1477444160
dev.em.0.rx_control: 67141634
dev.em.0.fc_high_water: 8192
dev.em.0.fc_low_water: 6692
dev.em.0.queue0.txd_head: 158
dev.em.0.queue0.txd_tail: 125
dev.em.0.queue0.tx_irq: 0
dev.em.0.queue0.no_desc_avail: 0
dev.em.0.queue0.rxd_head: 3624
dev.em.0.queue0.rxd_tail: 3623
dev.em.0.queue0.rx_irq: 0
dev.em.0.mac_stats.excess_coll: 0
dev.em.0.mac_stats.single_coll: 0
dev.em.0.mac_stats.multiple_coll: 0
dev.em.0.mac_stats.late_coll: 0
dev.em.0.mac_stats.collision_count: 0
dev.em.0.mac_stats.symbol_errors: 0
dev.em.0.mac_stats.sequence_errors: 0
dev.em.0.mac_stats.defer_count: 3404271
dev.em.0.mac_stats.missed_packets: 143616
dev.em.0.mac_stats.recv_no_buff: 0
dev.em.0.mac_stats.recv_undersize: 0
dev.em.0.mac_stats.recv_fragmented: 73
dev.em.0.mac_stats.recv_oversize: 0
dev.em.0.mac_stats.recv_jabber: 0
dev.em.0.mac_stats.recv_errs: 1545
dev.em.0.mac_stats.crc_errs: 1610
dev.em.0.mac_stats.alignment_errs: 0
dev.em.0.mac_stats.coll_ext_errs: 6
dev.em.0.mac_stats.xon_recvd: 3560624
dev.em.0.mac_stats.xon_txd: 0
dev.em.0.mac_stats.xoff_recvd: 43541329
dev.em.0.mac_stats.xoff_txd: 0
dev.em.0.mac_stats.total_pkts_recvd: 1393645238
dev.em.0.mac_stats.good_pkts_recvd: 1346464499
dev.em.0.mac_stats.bcast_pkts_recvd: 30744
dev.em.0.mac_stats.mcast_pkts_recvd: 8763
dev.em.0.mac_stats.rx_frames_64: 0
dev.em.0.mac_stats.rx_frames_65_127: 0
dev.em.0.mac_stats.rx_frames_128_255: 0
dev.em.0.mac_stats.rx_frames_256_511: 0
dev.em.0.mac_stats.rx_frames_512_1023: 0
dev.em.0.mac_stats.rx_frames_1024_1522: 0
dev.em.0.mac_stats.good_octets_recvd: 157771296534
dev.em.0.mac_stats.good_octets_txd: 3105799379404
dev.em.0.mac_stats.total_pkts_txd: 2289914278
dev.em.0.mac_stats.good_pkts_txd: 2289914278
dev.em.0.mac_stats.bcast_pkts_txd: 4776
dev.em.0.mac_stats.mcast_pkts_txd: 101790
dev.em.0.mac_stats.tx_frames_64: 0
dev.em.0.mac_stats.tx_frames_65_127: 0
dev.em.0.mac_stats.tx_frames_128_255: 0
dev.em.0.mac_stats.tx_frames_256_511: 0
dev.em.0.mac_stats.tx_frames_512_1023: 0
dev.em.0.mac_stats.tx_frames_1024_1522: 0
dev.em.0.mac_stats.tso_txd: 652240789
dev.em.0.mac_stats.tso_ctx_fail: 0
dev.em.0.interrupts.asserts: 1375041031
dev.em.0.interrupts.rx_pkt_timer: 0
dev.em.0.interrupts.rx_abs_timer: 0
dev.em.0.interrupts.tx_pkt_timer: 0
dev.em.0.interrupts.tx_abs_timer: 0
dev.em.0.interrupts.tx_queue_empty: 0
dev.em.0.interrupts.tx_queue_min_thresh: 0
dev.em.0.interrupts.rx_desc_min_thresh: 0
dev.em.0.interrupts.rx_overrun: 0
dev.em.0.wake: 0