Devices are required to comply with a protocol so the interrupt-request (IRQ) strains might be shared. The PCI bus involves four interrupt strains, INTA# by INTD#, all of which can be found to each unit. Up to eight PCI devices share the same IRQ line (INTINA# through INTINH#) in APIC-enabled https://nathanlabsadvisory.com/ciso-service/