Kernel in Operating System – Types, Objectives, and More

An operating system’s kernel is a key component that controls how hardware and computers function. In essence, it controls memory usage and CPU time. It forms the basis of an operating system. The kernel serves as a conduit for data processing at the hardware level through system calls and inter-process communication.

Kernel Overview

The most crucial component of the operating system is the kernel. It serves as the main conduit between a computer’s operations and hardware. The kernel’s connection between these two is to optimize resource allocation.

Because it functions inside the OS, akin to a seed inside a hard shell, it is referred to as a kernel. The kernel is one of the first programs to load into memory before the bootloader. Translating instructions for the central processing unit falls to the bootloader. It controls peripherals like keyboards and monitors in addition to memory.

The kernel in an operating system is located in a computer’s main memory (RAM) once the system is running. Initially, it is stored on the storage device(such as a hard drive or SSD) as part of the operating system files. During the boot process, a bootloader for the system’s operations.

In RAM, the kernel operates in a reserved and protected area called kernel space, separate from the user space where the application runs. This separation ensures stability and security, allowing the kernel to efficiently manage hardware resources, handle system calls, and perform essential tasks. The kernel remains in RAM throughout the system’s operations to provide the necessary speed and availability for managing the system.

Also read: Operating System Structure in OS: Exploring the Different Types

Objectives of Kernel

• Process Scheduling: Every process has a time allotment from the kernel. The kernel launches the subsequent process and determines its state (running, waiting, or ending) after the previous one has finished executing.
• Resource Allocation: The kernel controls memory, USB devices, and CPU processes. It distributes access to hardware components and memory and acts as a link between processes and resources.
• Device Management: The kernel is in charge of I/O and storage devices. It handles information flow by facilitating data exchange between these devices and applications.
• Handling Interrupts and System Calls: The kernel prioritizes and controls high-priority tasks and handles system calls and software interrupts.
• Memory Management: The kernel allocates and releases process memory. Memory holds running processes and releases them when they are finished.
• Process Management: The kernel is responsible for starting, stopping, and restarting the system’s processes and overseeing their management while a task is being completed.

Types of Kernel in Operating System

Kernels are categorized into five types. Let’s go through them one by one

Monolithic Kernels

In a monolithic kernel, the kernel and userspace share memory. This indicates that user services and kernel services share the same memory space. Since the OS uses the same amount of memory, its overall size increases. Since kernel and user services occupy the same memory space, processes run faster in this kernel type.

Examples: Unix, Linux, XTS-400, etc.

Microkernel

This kind of kernel implements user and kernel services in two distinct address spaces: kernel and user spaces. It may operate more slowly if numerous system calls and context switches are made, but it is simpler to administer and maintain than a monolithic kernel.

Microkernels offer only a few basic functions, such as memory address space definition, inter-process management, and process management. Other services, such as networking, are not provided by the Kernel. Rather, they are managed by a userspace application called Server.

When a process crashes in a microkernel, the error-causing services can be restarted to fix the problem without causing a system crash.

Examples: Amigos, Minix, L4, etc.

Hybrid Kernel

Microkernels and monolithic kernels are combined to create hybrid kernels. It combines the modularity of microkernels with the speed of a monolithic kernel. It is comparable to a microkernel but has some extra code in kernel space to improve system performance. While some services, such as network stacks, can be executed in kernel space, hybrid kernels still permit kernel code, such as device drivers, to operate as servers in user space.

Examples: Windows NT, BeOS, Netware, etc.

Nanokernel

The entire kernel code in Nanokernel is incredibly compact, indicating that very little code runs in the hardware’s privileged mode. Nanokernel’s word “nano” refers to its support for a nanosecond clock resolution.

Examples: EROS, etc.

Exokernel

Because resource protection and management are separate in Exokernel, we can customize it for individual applications. Exokernel adheres to the end-to-end idea, distributes physical resources among applications, and has as few hardware abstractions as possible.

Also Read: Multiprogramming Operating System – A Comprehensive Guide

What is the Function of a Kernel?

The kernel performs the following key functions.

• Hardware Abstraction provides a layer of abstraction over hardware devices, making it easier for applications to interact with them without knowing their specifications.

• System Calls Handling: This acts as an interface between user application and system hardware.

• Resource Allocation: This allocates CPU time, memory, and other resources to processes.

• Interrupt Handling: This responds to hardware interrupts to ensure smooth operations.

Role of Kernel in Operating System

The kernel plays a central role in an operating system’s functioning by managing system resources and bridging hardware and software. This ensures that multiple programs and processes can operate smoothly without referring to one another. The kernel handles process management by scheduling tasks and allocating CPU time. This also manages memory allocation, ensuring each process gets the necessary memory while preventing conflicts.

Additionally, the kernel controls device management, facilitating communication between hardware devices and software through device drivers. It manages file systems, enabling efficient data storage and retrieval. The kernel ensures system security by isolating processes and preventing unauthorized resource access. This also supports inter-process communication, allowing processes to share information and coordinate activities. Overall, the kernel’s role is critical in ensuring the efficient and secure operation of the operating system.

Also Read: The Most Commonly Asked OS Interview Questions

What is Kernel Panic?

As we have already discussed, the kernel controls the entire computer system; hence, it can shut down the system if it crashes. In MacOS and Linux, this undesirable event is known as Kernel Panic. To recover from a Kernel Panic, we need to restart the system.

Hardware communication issues usually cause these kernel panics. If they occur repeatedly, try unplugging unnecessary or less-required devices and check if the problem is resolved.

Also Read: Classification of Operating System

Conclusion

A Kernel is one of the core parts of an operating system and is the first thing that loads when a system is booted. It stays in the memory while the system is running. Kernels are divided into five parts based on their function: monolithic, microkernel, nanokernel, hybrid, and exokernel. The kernel is assigned many important things like scheduling tasks, managing resources, handling devices, and dealing with memory. Some common examples of kernels are Zircon, Linux, and Windows NT.

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