- event that alters the normal flow of a program
- can be generated by hardware devices or by the CPU itself
- physically produced by electronic signals generated by hardware and directed to the input pins on an
interrupt controller.
- Based on the source of interrupt :
- Synchronous → Generated by executing an instruction (Eg : syscalls, Divide by Zero)
- Asynchronous → Based on external event (Eg : Key presses on keyboard)
- Based on ability to temporarily disable :
- Maskable → can be ignored; it is signaled via INT pin
- Non-Maskable → cannot be ignored ; it is signaled via NMI pin
An interrupt controller is a simple chip that multiplexes multiple interrupt lines into a single interrupt line on the processor.
- when an interrupt occurs, the current flow of execution is stopped and the interrupt handler runs (unless interrupts are disabled for critical sections)
- Each interrupt has a unique value assigned to it so that interrupts from 2 different devices can be differentiated. These values are called
Interrupt Request (IRQ) lines.
TODO: add flow excali svg here
TODO: add backlinks here
Their are 4 ways to defer work in Bottom Half
- softirq
- tasklet
- workqueue (replacement of task queues)
- kernel Timer