Equipment are necessary to follow a protocol so the interrupt-ask for (IRQ) lines is usually shared. The PCI bus incorporates four interrupt traces, INTA# through INTD#, all of which can be obtained to every product. Around 8 PCI devices share a similar IRQ line (INTINA# via INTINH#) in APIC-enabled x86 https://nathanlabsadvisory.com/fedramp/