em broken on current amd64

[Warren Block]

On Sat, 12 Sep 2015, Mark R V Murray wrote:

> I just caught this, on today’s build:
>
> em0: Watchdog timeout Queue[0]-- resetting
> Interface is RUNNING and ACTIVE
> em0: TX Queue 0 ------
> em0: hw tdh = 127, hw tdt = 139
> em0: Tx Queue Status = -2147483648
> em0: TX descriptors avail = 1012
> em0: Tx Descriptors avail failure = 0
> em0: RX Queue 0 ------
> em0: hw rdh = 0, hw rdt = 1023
> em0: RX discarded packets = 0
> em0: RX Next to Check = 0
> em0: RX Next to Refresh = 1023
>
> [graveyard] /usr/ports 09:42 pm # uname -a
> FreeBSD graveyard.grondar.org 11.0-CURRENT FreeBSD 11.0-CURRENT #0 r287705: Sat Sep 12 15:07:54 BST 2015     root at graveyard.grondar.org:/b/obj/usr/src/sys/G_AMD64_GATE  amd64

That happened on an amd64 10-STABLE (r287148) system here a couple of 
days ago.  Both I217-V and 82574L cards in that system, but I did not 
save the message and can't say which had the error.  Never seen before, 
has not happened again.