APIC trigger mode

Hi there,

I have a question regarding the APIC-interrupt mode settings on x86. I
see that one has to set the mode externally in Fiasco.OC using the
'l4_icu_set_mode' call. Also I had a look at Nova which seems to program
these modes from within the kernel, using edge/high for IRQ 0-15 and
level-low for IRQ 16-23. Would that be a valid assumption to program the
modes for Fiasco.OC x86 also, or is there an other way to find out the
interrupt-trigger modes of IRQs (other than the ones found in
ACPI-MADT)? Why is it necessary to set these modes outside the kernel?

Thanks a lot,

Sebastian