Products are needed to follow a protocol so which the interrupt-request (IRQ) lines is usually shared. The PCI bus features 4 interrupt lines, INTA# through INTD#, all of which are offered to every unit. As much as 8 PCI products share the identical IRQ line (INTINA# via INTINH#) in APIC-enabled https://nathanlabsadvisory.com/3rd-party-security-audit-assessment/