Design and Implementation of Linux kernel (1)-kernel introduction,

Design and Implementation of Linux kernel (1)-kernel introduction,

This article briefly introduces the basic concepts related to the kernel.

Main content:

• Single Kernel and micro kernel
• Kernel version number

 

1. Single Kernel and micro kernel

	Principle	Advantages	Disadvantage
Single Kernel	The entire kernel runs in a large kernel address space.	1. Simple. 2. Efficiency: All kernels are in a large address space. Therefore, the calling of each function in the kernel is similar to calling a function, with almost no performance overhead.	A function crash will make the entire kernel unusable.
Microkernel	The kernel is divided into independent processes by function. Each process runs independently in its own address space.	1. Security: Various kernel services run independently. If a service fails, other services will not be affected.	Calls between services in the kernel involve inter-process communication, which is complex and inefficient.

 

Although the Linux kernel is based on a single kernel, after so many years of development, it also has some features of the micro kernel. (Embodies the principle of Linux practicality first)

It has the following features:

2. kernel version number

The kernel version number consists of four arrays. For example, version: 2.6.26.1 where,

2-major version number

6-slave version number or secondary version number

26-revision version number

1-stable version number

The minor version number indicates that this version is a stable version (Even) Or the development version (OddIn the preceding example, the version number is stable.

Stable versions can be used in enterprise-level environments.

Updates to revision versions include BUG fixes, new drivers, and new feature additions.

The stable version number is mainly used to modify some key bugs.