System hangs at boot in xhci0

[Steve Kargl]

I updated my system to 

% svn info /usr/src
Path: /usr/src
Working Copy Root Path: /usr/src
URL: svn://svn.freebsd.org/base/head
Relative URL: ^/head
Repository Root: svn://svn.freebsd.org/base
Repository UUID: ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Revision: 309748

Built a shiny new kernel, which hangs during boot.
There is no panic.  Using the dmesg from kernel.old/kernel,
the last few reported are 


pci2: <ACPI PCI bus> on pcib2
xhci0: <XHCI (generic) USB 3.0 controller> mem 0xfe900000-0xfe900fff irq 48 at device 0.0 on pci2
xhci0: 32 bytes context size, 64-bit DMA

At this point, the system is completely unresponse and
needs to be power cycled.

-- 
steve