"Linux kernel design and implementation" reading notes (i)-Introduction to the kernel

This article provides a brief introduction to kernel-related basic concepts.

Main content:

• Single Core and micro core
• Kernel version number

1. Single Core and micro-core

	principle	Advantage	disadvantage
single core		1. Simple. 2. Efficient: All cores are in a large address space, so calls and call functions are similar between functions of the kernel, with little performance overhead.
micro-kernel	The kernel is divided into individual processes by function. Each process runs independently on its own address space.	1. Security: The various services of the kernel run independently and a service hangs without affecting other services.

Linux kernel is based on a single kernel, but after so many years of development, but also has some characteristics of micro-kernel. (It embodies the principle of practical supremacy of Linux)

The main features are:

1. Supports dynamic loading of kernel modules
2. Supports symmetric multi-processing (SMP)
3. The kernel can preempt (preemptive), allowing the kernel to run tasks with the ability to prioritize execution
4. Do not differentiate between threads and processes

2. Kernel version number

The kernel has a version number consisting of four main arrays. such as version number: 2.6.26.1 which,

2-Major Version number

6-from the version number or the secondary version number

26-Revision Number

1-Stable version number

The secondary version number indicates whether this version is stable ( even ) or development ( odd ), and the version number in the example above is stable.

A stable version is available for enterprise-class environments.

upgrades to revision numbers include bug fixes, new drivers, and additions to new features.

The stable version number is primarily a modification of some critical bugs.

"Linux kernel design and implementation" reading notes (i)-Introduction to the kernel