kern/52789: Network interfaces only work when carrier is active

[Pierre Pronchery <khorben%defora.org@localhost>]

>Number:         52789
>Category:       kern
>Synopsis:       Disconnecting the ethernet cable breaks local connectivity
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Dec 07 11:50:00 +0000 2017
>Originator:     Pierre Pronchery <khorben%defora.org@localhost>
>Release:        NetBSD 8.0_BETA
>Organization:
>Environment:
System: NetBSD hostname 8.0_BETA NetBSD 8.0_BETA (GENERIC) amd64
Architecture: x86_64
Machine: amd64
>Description:
Local connectivity to Ethernet interfaces is lost when the carrier is
not active. I believe this is not expected behaviour. I observe it on
8.0_BETA, as opposed to 7.1_STABLE for instance.
>How-To-Repeat:
# ifconfig wm0
wm0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        capabilities=7ff80<TSO4,IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx>
        capabilities=7ff80<TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx,TCP6CSUM_Rx>
        capabilities=7ff80<TCP6CSUM_Tx,UDP6CSUM_Rx,UDP6CSUM_Tx,TSO6>
        enabled=0
        ec_capabilities=7<VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU>
        ec_enabled=0
        address: 00:01:02:03:04:05
        media: Ethernet autoselect (none)
        status: no carrier
        inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
# ping -c 1 192.168.0.1
PING 192.168.0.1 (192.168.0.1): 56 data bytes

----192.168.0.1 PING Statistics----
1 packets transmitted, 0 packets received, 100.0% packet loss
[connect Ethernet cable with link]
# ifconfig wm0
wm0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        capabilities=7ff80<TSO4,IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx>
        capabilities=7ff80<TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx,TCP6CSUM_Rx>
        capabilities=7ff80<TCP6CSUM_Tx,UDP6CSUM_Rx,UDP6CSUM_Tx,TSO6>
        enabled=0
        ec_capabilities=7<VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU>
        ec_enabled=0
        address: 00:01:02:03:04:05
        media: Ethernet autoselect (100baseTX full-duplex)
        status: active
        inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255
# ping -c 1 192.168.0.1 
PING 192.168.0.1 (192.168.0.1): 56 data bytes
64 bytes from 192.168.0.1: icmp_seq=0 ttl=255 time=0.232216 ms

----192.168.0.1 PING Statistics----
1 packets transmitted, 1 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.232216/0.232216/0.232216/0.000000 ms
>Fix:
Unknown as of yet.