Fatal trap 12 during bootup on Dell Cpt with acpi enabled

[LordYoukai]

I was experimenting with the latest Dragonfly build on a spare Dell Cpt 
laptop. If you boot with acpi enabled, you get a kernel fault right 
after it outputs "ata0: <ATA channel 0> on atapci0"

The full text is as follows:

Fatal trap 12: page fault while in kernel mode
fault virtual address = 0
fault code = supervisor write, page not present
instruction pointer = 0x8:0xc082d871
stack pointer = 0x10: 0xc6f31d2c
frame pointer = 0x10:0xc6f31d38
code segment = base 0x0, limit 0xfffff, type 0x1b
             = DPL 0, pres 1, def32 1, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process = Idle
current thread = pri 12
kernel: type 12 trap, code = 2
Stopped at AcpiReadBitRegister+0x46:   movl %eax,0(%edx)
db>
---

I am uncertain what else to do - I have left the laptop as is, so if you 
have any commands for me to input, it is a definite.

Ben