ohci bricks a amd64 system

I updated my FreeBSD-current system from an
April 9th kernel/world (r264280M, which was
running fine) to today sources (r267284), and
have successfully turned the system into a brick
if I include the USB ohci device in my kernel.
During the verbose boot process, the brick stops
with the message

ohci early: SMM active, request owner change

At this point, one must hit the reset button
as there is no keyboard, yet.  If I remove the
ohci device from the kernel config file, the
resulting kernel boots but the usb mouse is
no longer available.

Any pointers on how to debug/fix the ohci device
is appreciated.

-- 
Steve