Devices are necessary to comply with a protocol so that the interrupt-request (IRQ) lines is often shared. The PCI bus includes 4 interrupt traces, INTA# by way of INTD#, all of which are available to every unit. Around 8 PCI units share exactly the same IRQ line (INTINA# through INTINH#) https://nathanlabsadvisory.com/eu-us-privacy-shield-gdpr/