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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 carried out 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 purpose of 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. One of the first programs to load into memory before the boot loader is the kernel. The task of translating instructions for the central processing unit falls to the boot loader. It controls peripherals like keyboards and monitors in addition to memory.

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 end) after the previous one has finished executing.
• Resource Allocation: Memory, USB devices, and CPU processes are all controlled by the kernel. Access to hardware components and memory is distributed by it, acting as a link between processes and resources.
• Device Management: I/O and storage devices are among the system devices that the kernel is in charge of. It handles information flow by facilitating data exchange between these devices and applications.
• Handling Interrupts and System Calls: High-priority tasks are given priority by the kernel, which also controls task priorities. System calls, which are essentially software interrupts, are also handled by it.
• Memory Management: Process memory is allocated and released by the kernel. Memory is used to hold running processes and released when they are finished.
• Process Management: The kernel is in charge of starting, stopping, and restarting the system’s processes. It oversees the management of the process while a task is being completed.

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

Monolithic Kernels

In a monolithic kernel, the memory space is shared by the kernel and userspace. 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 both kernel and user services occupy the same memory space, processes run more quickly in this type of kernel.

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

Microkernel

The user and kernel services in this kind of kernel are implemented into two distinct address spaces, or 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.

Only a few basic functions, such as memory address space definition, inter-process management, and process management, are offered by microkernels. 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 in order to improve system performance, it also has some extra code in kernel space. 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 userspace.

Examples: Windows NT, BeOS, Netware, etc.

Nanokernel

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

Examples: EROS, etc.

Exokernel

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

What is Kernel Panic?

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

Usually, these kernel panics are caused by hardware communication issues. Hence, if repeated kernel panics are occurring, then try to unplug the less required or unnecessary devices and check if the problem is resolved or not.

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 throughout the system is in running state. Kernels are divided into five parts on the basis of their function which are: monolithic, microkernel, nanokernel, hybrid, and exokernel. The kernel is assigned with a lot of important things like scheduling tasks, managing resources, handling devices, and dealing with memory. Some of the common examples of kernels are Zircon, Linux, and Windows NT.