Products are required to follow a protocol so the interrupt-request (IRQ) strains is often shared. The PCI bus involves 4 interrupt traces, INTA# through INTD#, all of which are available to each system. Approximately eight PCI gadgets share precisely the same IRQ line (INTINA# by INTINH#) in APIC-enabled x86 devices. https://nathanlabsadvisory.com/copyright-certified-information-system-security-professional/