em lockups during heavy network I/O on RELENG_7

[Josh Carroll]

> There's another thread on this issue, although that thread seems to
> apply to a specific version (of em(4) code, or of NIC PROM revision -- I
> don't know, the dmesg output is somewhat ambiguous).

Ah sorry, I did see that thread, but did notice the em version was
different, and that it didn't appear to be causing a hard lock of the
machine. I suppose it could be related, though. Should I track/post to
that thread, instead? Sorry if this is a duplicate issue, but it
seemed the symptoms were different.

Thanks,
Josh