8.1-RELEASE em watchdog timeout broken?

[Scott Johnson]

Under 8.0-RELEASE I would get warnings from em(4) in /var/log/messages about 

"watchdog timeouts" on em0 whenever my desktop PC connected to em0 was powered 
off. This was fine, except for the annoying warnings.

Under 8.1-RELEASE I no longer get the warnings, and any time my desktop is 
powered off, when I turn it back on, it has no connectivity. The interface is 
dead until I log into the console and run:
# ifconfig em0 down up

The em(4) driver has changed a lot since 8.0-RELEASE. It seems this watchdog 
timeout is no longer working.

The board is a Supermicro X7SPA-H with Intel 82574L GbE.

Any ideas for debugging?