panic during kernel build

[John]

Trying to build a kernel:

db> t
Debugger() at Debugger+0x4b
panic() at panic+0x167
ohci_add_done() at ohci_add_done+0x66
ohci_intr1() at ohci_intr1+0x185
ohci_intr() at ohci_intr+0x29
ithread_loop() at ithread_loop+0x17d
fork_exit() at fork_exit+0xd9
fork_trampoline() at fork_trampoline+0xe
--- trap 0, rip = 0, rsp = 0xffffffffb1e6cd30, rbp = 0 ---


I don't have any usb (ohci?) hardware. However, I do not have
usb disabled in the bios.

thoughts?

-John