Meaning – The term interrupt number, refers to the identification that is used to send a signal from an installed hardware feature to the CPU requesting attention. Different hardware features use different interrupt numbers.
When registering interrupts the driver must provide the system with an interrupt number. This interrupt number identifies the interrupt specification for which the driver is registering a handler. Most devices have one interrupt: interrupt number 0. However, there are devices that have different interrupts for different events. A communications controller may have one interrupt for receive ready and one for transmitting readily. The device driver normally knows how many interrupts the device has, but if the driver has to support several variations of a controller, it can call ddi_dev_nintrs to find out the number of devices interrupts.
Example of usage – “An Interrupt Request is a signal from a hardware device on your computer to your CPU. When a hardware device needs the CPU to do something (such as move the cursor as you move the mouse), the device sends an Interrupt Request to the CPU.”