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May 23, 2022 |50.3K Views
Kernel in Operating System
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The kernel is the main component of an operating system. It is the first program that is loaded by the bootloader when the system is switched on. It remains in the memory till the system is shut down. The kernel is an interface between the user application programs and the hardware. An operating system can never function without a kernel.

The main functions of the kernel are:

1) Resource management: Kernel ensures that the resources are correctly shared among different processes.
2) Memory management: Allocation and Deallocation of memory among various processes.
3) Disk Management: It manages the secondary storage devices.

The kernel manages the interaction between user application programs and system hardware.

There are main five types of the kernel in the operating system, which are as follows:
1) Monolithic kernel
2) Micro Kernel
3) Hybrid Kernel
4) Exo Kernel
5) Nano Kernel

1) Monolithic Kernel: Mono means single, in monolithic kernel, both user and kernel space occupy the same memory area. Response time of a monolithic kernel is very low which leads to fast performance of the system. In monolithic kernel, kernel size is large because of the large size of the code. The most common example of monolithic kernel is unix, linux.

2) Micro Kernel: In Micro Kernel, user services and kernel services are implemented in separate memory areas. Microkernels are smaller in size as compared to monolithic kernel and very highly stable because of less services in the kernel space. It requires a large number of system calls and context switches.  The most common example of microkernel are AmigaOS, and Minix.

3) Hybrid Kernel: Hybrid kernel is the mixture or combination of monolithic and micro kernel. In hybrid kernel some non-essential code is kept in the kernel space to speed up the execution process. As it is the combination of Monolithic and microkernel so it is as fast as monolithic kernel and as stable as microkernel. The common example of hybrid kernel are: windows NT, Netware.

4) Exo Kernel: Exo kernel was developed by MIT, it focuses on application-level management of resources. It provides a low-level interface. Exo kernel separates security and management of resources. It increases work for the application developers. Te common example of Exo Kernel  are Nemesis, ExOs.

5) Nano Kernel: Nano stands for small, so here nano refers to the size of the kernel. The size of nano kernel is very small as compared to other kernels. It’s design closely resembles to Micro kernel, as it has hardware abstraction and do not provide system services. In nano kernel most of the code is present in the kernel space. The common example of Nano kernel is EROS.

Kernel is OS: https://www.geeksforgeeks.org/kernel-in-operating-system/

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