Gadgets Are needed to stick to a protocol so the interrupt-ask for (IRQ) traces can be shared. The PCI bus includes four interrupt traces, INTA# via INTD#, all of which can be obtained to every gadget. Approximately 8 PCI gadgets share a similar IRQ line (INTINA# by way of INTINH#) https://nathanlabsadvisory.com/security-program-advisory/