Linux Kernel introduction, version number, and release history

1. Linux kernel Introduction

Linux is the most popular operating system kernel for free computers. It is a UNIX-like operating system written in C language that complies with POSIX standards. Linux was first developed by Finnish hacker Linus Torvalds to try to provide a free UNIX-like operating system on intel X86 architecture. The plan started in 1991. Here is a post posted by Linus Torvalds in the USENET newsgroup comp. OS. minix, which marks the official start of the Linux program.

Some minix hackers helped in the early stages of the plan, and today countless programmers around the world are providing free help for the plan.

Technically speaking, Linux is a kernel. "Kernel" refers to a system software that provides hardware abstraction layer, disk and file system control, multi-task, and other functions. A kernel is not a complete operating system. A complete Linux kernel-based operating system is called Linux or GNU/Linux.

Linux is a monolithic kernel system. The device driver has full access to the hardware. The device drivers in Linux can be conveniently set in the form of modularize and can be directly loaded or uninstalled during system operation.

Linux Kernel Components:
Process Management, timer, interrupt management, memory management, and module Management), Virtual File System Interface (VFS layer), file system, device driver, and inter-process communication), network management, system init, and other operating system functions.

 

Ii. Linux kernel version

Method 1:

The kernel is a low-level supporting software used to deal with hardware and provide a limited service set for user programs. A computer system is a symbiosis between hardware and software. They are mutually dependent and inseparable.

The Linux version is divided into two parts: the kernel version and the release version. The kernel version number consists of three numbers: R. x. y.

R: The current main version of the kernel.
X: an even number indicates a stable version, and an odd number indicates a development version.
Y: The number of times the error is fixed.

In general, a version with an even number of digits is a stable version that can be used, such as 2.4.4; a version with an odd number of digits generally includes some new content, which may not be stable, is a test version, such as 2.1.111.

 

Method 2:

Major. Minor. patch-build.desc

2.26.35-RC5

1. Major:Indicates the main version number, which is changed only when there is a structural change.

2. Minor:Indicates the minor version number and changes only when new features are added. an odd number indicates the test version and an even number indicates the production version.

3. patch:Indicates the number of revisions or patch packages of the minor version.

4. Build:Indicates the number of times of compilation (or build). Each compilation may optimize or modify a small number of programs, but there is generally no major (controllable) Functional change.

5. Desc:It is used to describe the special information of the current version. Its information is specified during compilation, which is relatively random. However, some descriptive identifiers are commonly used, such:

<1> RC (sometimes with a letter R) represents the release candidate. The number after RC represents the candidate versions of the official version. In most cases, the larger the number of candidate versions is, the closer it is to the official version.

<2> SMP, indicating symmetric multi-processor ).

<3> PP is often used to represent the test version (pre-patch) in Red Hat Linux ).

<4> El, used in Red Hat Linux to represent Enterprise Linux ).

<5> MM indicates the version used to test new technologies or new functions.

<6> FC, which indicates Fedora Core in Red Hat Linux.

 

If you are on a production machine, it is best not to install a kernel with an odd version number. Similarly, the kernel version of pre-patch is not recommended to be installed on the production machine.

 

Iii. Release history of Linux kernel

The kernel is an important part of the Linux system. Every release of the new kernel version is concerned by Linux enthusiasts. The following table lists important development events of the Linux kernel.

Kernel version number	Time	Kernel Development History
0.00	1991.2-4	The two processes respectively display aaa bbb
0.01	1991.9	First officially released Linux kernel version
0.02	1991.10.5	Linus Torvalds released the first 0.02 kernel version to the minix newsgroup, and soon got a response. Linus Torvalds expands on this simple task switching mechanism and, with the help of many enthusiastic supporters, develops and releases the first stable working version of Linux.
0.03	1991.10.5
0.10	1991.10	The kernel version of linux0.10 was released, and version 0.11 was later released in December 1991, when it was released on the Internet for free.
0.11	1991.12.8	The kernel version that can run normally.
0.12	1992.1.15	It mainly includes software simulation programs for the mathematical coprocessor.
0.95 (0.13)	1992.3.8	Start to join the kernel version of the Virtual File System idea
0.96	1992.5.12	Start to join network support and Virtual File System
0.97	1992.8.1
0.98	1992.9.29
0.99	1992.12.13
1.0	1994.3.14	With the release of the Linux kernel, more and more users are using it, and the core development team of Linux has also been built.
1.2	1995.3.7
2.0	1996.2.9
2.2	2.16.1.26
2.4	2001.1.4	The kernel of linux2.4.0 is released.
2.6	2003.12.17	The Linux 2.4 kernel is released. Compared with the kernel version, it has been improved in many aspects, such as supporting multi-processor configuration and 64-bit computing, it also supports nptl for efficient thread and processing ). In fact, performance, security, and driver improvements are the key to the entire 2.6.x kernel.
2.6.15	2006	Linux Kernel 2.6.15 is released. Its IPv6 support has been greatly improved in this kernel. PowerPC users now have a generic tree for 64-bit and 32-bit PowerPC, which makes kernel editing on both architectures possible.
2.6.30	2009.6	Improved the file system, added the integrity check patch, tomoyo Linux security module, and reliable data PACKET socket) protocol Support, OSS support, FS-cache file system cache layer, nilfs file system, thread interrupt processing support, and so on.
2.6.32	2009.12	Added virtual memory de-duplicacion, rewritten writeback code, improved btrfs file system, added ATI r600/r700 3D and kms support, CFQ low transmission delay time mode, perf timechart Tool the Memory Controller supports Soft Limits, S + core architecture, Intel moorestown and its new firmware interfaces, runtime power management, and new drivers.
2.6.34	2010.5	Two new file systems, CEpH and logfs, are added. The former is a distributed file system, and the latter is a file system suitable for flash devices. Other features of Linux kernel 2.6.34 include the new vhost net, improved btrfs file system, optimized kprobes jump, new perf functions, RCU lockdep, and generalized TTL security mechanisms (RFC 5082) and Private VLAN proxy ARP (RFC 3069) support, asynchronous Resume.
2.6.36	2010.10	Supported by the tilera processor architecture, new file notification interfaces fanow.intel graphics card, integration of kms and KDB, parallel management of work queues, and smart power of built-in graphics card and CPU on Intel I3/5 Platform management, CIFS File System local cache, improve the hierarchical structure of virtual memory, improve the desktop operation response speed, improve the virtual memory overflow Terminator algorithm, and integrate the apparmor Security Model (Note: Unlike SELinux file-based tagging, apparmor is path-based ).