Brief presentation of interrupts
On many platforms, a special device is responsible for managing IRQ lines. That device is the interrupt controller and it stands between the CPU and the interrupt lines it manages. The following is a diagram that shows the interactions that take place:
Figure 13.1 – Interrupt controller and IRQ lines
Not only can devices raise interrupts, but some processor operations can do that too. There are then two different kinds of interrupts:
- Synchronous interrupts, called exceptions, are produced by the CPU while processing instructions. These are non-maskable interrupts (NMIs) and result from a critical malfunction such as hardware failure. They are always processed by the CPU.
- Asynchronous interrupts, called interrupts, are issued by other hardware devices. These are normal and maskable interrupts. These are what we will discuss in the next sections of this chapter.
Before getting deeper into interrupt management...