HEAD can't bring up APs on Intel LC5528(Jasper Forest)

I'm trying to bring up a new board based on Intel's Jasper Forest x86
processor.  I can boot a kernel without SMP without any problems, but
FreeBSD is not able to start up the Application Processors if I enable
SMP.  The error message that I get is:

AP #2 (PHY# 2) failed!
panic y/n? [y]

This was a i386 kernel built from HEAD as May 2nd or so.  It's not
always PHY#2.  Some number of APs manage to start up correctly, but
one usually fails.  I have observed one instance where all of the APs
came up properly, so it seems as though there's some kind of race that
I stand a very good chance of losing at least one time in seven tries.
 If I disable all but one AP through device.hints I stand a pretty
good chance of successfully starting that AP and booting correctly.

I've been banging my head against the wall for a while now and all
indications are that the AP never starts at all.  I enabled the
CHECK_POINTS compile-time option and and nothing ever gets written to
the CMOS for the AP that fails to start.  Writing to the CMOS is the
second thing that the AP does after doing a cli so it's a good bet
that the AP never hits that code.

Linux (version 2.6.28-11) is able to boot and start the APs just fine.
 My suspicion is that Linux is explicitly configuring something that
FreeBSD is trusting the BIOS to do.

We do have the reference board around, but we're having trouble
getting the original Intel BIOS programmed into it.  If we can get
that working again I'll let you know whether FreeBSD can boot on it.

If anybody can offer any hints or ideas for debugging this it'd be
greatly appreciated, as right now I'm reduced to grasping at straws.