em driver, 82574L chip, and possibly ASPM

[Ivan Voras]

It looks like I'm unfortunate enough to have to deploy on a machine 
which has the 82574L Intel NIC chip on a Supermicro X8SIE-F board, which 
apparently has hardware issues, according to this thread:

http://sourceforge.net/tracker/index.php?func=detail&aid=2908463&group_id=42302&atid=447449

One of the proposed workarounds is disabling "Active State Power 
Management" in the BIOS and in the OS.

I have disabled it in BIOS but I don't know how to disable it in FreeBSD 
(apparently only disabling it in BIOS isn't enough).

Any ideas on how to achieve the effect in FreeBSD?