WOL question

I am hoping someone here who has more familiarity with the ACPI
code can enlighten me....

I have an internal bug filed complaining that FreeBSD disables
wake-on-lan on the hardware. This means that if you boot, say,
Linux, even Knoppix as a quickie, and then shutdown, if the
hardware supports it, it will be left in a state where a magic-packet
wakeup will work. However, even if I boot up a FreeBSD kernel
with NO em driver, and then shutdown, it undoes the WOL setup.

Now, I would like to have explicit WOL support added into the
em driver, but before I even worry about that I need to understand
where the kernel turns this off without the driver even needed.

I've looked around at the dev/acpi and arch/acpi code and at
least so far I'm having a hard time getting an adequate picture
to know how it happens.

Jack