psm0: unable to allocation IRQ (solution, well workaround)

I recently stumbled across this bug, and I have a solution to my
specific case.

The problem is the following:
acpi_ibm0: <IBM ThinkPad ACPI Extras> irq 12 on acpi0


_IF_, I put "device acpi_ibm" into the kernel config, disaster, psm0 is
unable to attach.

If I "acpi_ibm_load="YES"" in /boot/loader.conf, I then get the
following:
acpi_ibm0: <IBM ThinkPad ACPI Extras> on acpi0

Note the lack of "irq12"

Which then frees up:

psm0: <PS/2 Mouse> irq 12 on atkbdc0


Now, psm0 maps its IRQ as RF_SHAREABLE, so it _should_ work regardless,
right?

I'd regard this as a fairly serious bug.

I'm really at a loss of where to track it down more, looking at the
acpi_ibm code, its pretty opaque as to how resource allocations are done
and why this would ever map irq 12 (well, at least to me).

-- 
David E. Cross