em promiscuous mode bug?

Hi

It seems that placing an em(4) interface into promiscuous mode the
card stops doing hardware offload of 802.1Q tagging, in fact, it
stops tagging entirely if vlanhwtag is enabled on the card.

With vlanhwtag:
15:40:48.050645 00:00:5e:00:01:02 > 01:00:5e:00:00:12, ethertype IPv4 (0x0800), length 70: (tos 0x10, ttl 255, id 44821, offset 0, flags [DF], proto: VRRP (112), length: 56) 196.30.82.61 > 224.0.0.18: VRRPv2, Advertisement, vrid 2, prio 10, authtype none, intvl 1s, length 36, addrs(7): 157.248.206.115,76.246.42.167,148.235.231.80,70.180.123.113,201.169.28.232,19.31.18.203,59.148.50.175

Without vlanhwtag:
15:40:57.419522 00:00:5e:00:01:02 > 01:00:5e:00:00:12, ethertype 802.1Q (0x8100), length 74: vlan 1001, p 0, ethertype IPv4, (tos 0x10, ttl 255, id 44867, offset 0, flags [DF], proto: VRRP (112), length: 56) 196.30.82.61 > 224.0.0.18: VRRPv2, Advertisement, vrid 2, prio 10, authtype none, intvl 1s, length 36, addrs(7): 157.248.206.115,76.246.42.176,8.148.142.115,171.178.137.11,211.216.40.239,67.124.122.122,253.155.32.152

The interface is placed in promiscuous mode by the carp driver.

em0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
        options=cb<RXCSUM,TXCSUM,VLAN_MTU,POLLING,VLAN_HWCSUM>
        ether 00:04:23:cf:50:00
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active

vlan1001: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
        inet 196.30.82.62 netmask 0xfffffff0 broadcast 196.30.82.63
        ether 00:04:23:cf:50:00
        media: Ethernet autoselect (1000baseTX <full-duplex>)
        status: active
        vlan: 1001 parent interface: em0

carp1001: flags=49<UP,LOOPBACK,RUNNING> mtu 1500
        inet 196.30.82.60 netmask 0xfffffff0 
        carp: BACKUP vhid 2 advbase 1 advskew 0

I've also noticed that the re(4) driver on the 8169 chip miss-tags
frames when vlanhwtag is enabled.

Ian

--
Ian Freislich