The “/proc” file-system provides details of the interrupts generated in the system. The output of “/proc/interrupts” is provided below. 

The output of “/proc/interrupts” shows all the different interrupts that have handlers (Interrupt Service Routines – ISRs) registered for them. The first column indicates the IRQ number. Subsequent columns indicate how many interrupts have been generated for the IRQ number on different CPU cores. The last column provides information on the programmable interrupt controller that handles the interrupt. 

We will attempt to understand an ISR and write an ISR that handles the keyboard interrupt. This is handled by IRQ1 in the table above and i8042 controller which handles keyboard and mouse inputs

Interrupt Service Routine (ISR)