How does the hardware support interrupt handling in the processor?

Operating SystemHardwareSoftware & Coding

Interrupts are generally called signals which are generated by the software or hardware when a particular event or process requires immediate attention. So, the signal informs the processor about a high priority and urgent information demand causing interruption in the current working process.

Thus, whenever an interruption occurs the processor finishes the current instruction execution and starts the execution of the interrupt known as interrupt handling. Moreover, for every interrupt handling to occur there is an Interrupt service routine (ISR) or interrupt handler.

Interrupt handling in modern operating systems −

In several operating systems such as Linux.mac or windows Interrupt handling is divided into two parts −

First-level interrupt handlers (FLIH), also known as hard interrupt handlers or fast interrupt handlers

Second-level interrupt handlers(SLIH), also known as slow interrupt handlers or soft interrupt handlers

The uses and properties of FLIH and SLIH are −


  • are platform-specific interrupt handling

  • It causes jitter in the execution of the process.

  • It also masks interrupts

  • FLIH is known as the upper half in Linux


  • it completes long interrupt processing tasks similar to the process or event.

  • have dedicated thread for each single handler.

  • it has a long-lived execution time

  • SLIH is known as the Lower half or bottom half in Linux.

The interrupt handling mechanism of an operating system accepts a number which is an address and then selects what specific action to be taken which is already mentioned in the interrupt service routine. In most architecture the address in stored in a table known as a vector table.

Hardware support for interrupt handling in the processors

With all the recent processors and technical advancements, interrupt handling is added to the hardware.

The below paragraph explains about interrupt handling using hardware −

  • All the available processors have a mechanism which translates the interrupt or exception into an interrupt handling.

  • Different processors provide different ways for handling the interrupts. The most important one is storing the interrupt in hardware interrupt is using vector tables.

Uses of the interrupt handling of a network card

The step by step process of the network card and its interrupt handling is as follows −

  • The network device stores the packet in the device memory in a buffer.

  • An interrupt is raised on the network.

  • The interrupt acknowledges and initializes a new socket buffer.

  • The handler copies the packet from the device memory.

  • The handler invokes a function to find the protocol through which the packet is encapsulated.

  • The interrupt handler notifies the networking code with information of new arrival of data.

Published on 01-Dec-2021 13:08:02