At system startup, PCI device is detected and the correct interrupt is allocated (units of measurements, it equals 9).
But the PCI device does not work correctly and sign the required interrupt fails - exhibited 0.

We can then programmatically change this interrupt Interrupt_Line features PCI BIOS (_CA_PCI_Write_).

But we would like to know what interrupt is like when you start to allocate that device POST.

If we look at "show_pci-vvvvv" then map irq routing table already featured 0.

How to understand (to catch, request), and how to assign an interrupt PLAN?