Devices are necessary to comply with a protocol so the interrupt-ask for (IRQ) traces is usually shared. The PCI bus involves four interrupt traces, INTA# by means of INTD#, all of which can be obtained to each device. Approximately 8 PCI gadgets share a similar IRQ line (INTINA# via INTINH#) https://nathanlabsadvisory.com/cloud-computing-security/