Linux kernel version

Under Linux there is a directory, the/usr/src/kernels/directory, the following is a Linux system kernel file,

For example: 2.6.18-164.el5-x86_64, 2.6.18-8.el5-x86_64, and 2.6.18-194.el5-x86_64, what do these file numbers mean? For example, what does 2.6.18 mean? What does the El5 represent? What does the x86_64 represent?

Classification of Linux kernel versions
There are two versions of the Linux kernel: stable and development, and the Linux kernel version number consists of 3 sets of numbers: the first group number. The second set of numbers. Number three

First group number: The major version of the kernel that is currently released.

Second group number: even for stable version, odd for developing version.

Third group number: number of error fixes.

Example 1:2.6.18-128.ELSMP,

Number of first group: 2, Major version number

Second group number: 6, minor version number, indicating stable version (because there are even)

The third group number 18, revision number, indicating the number of changes, the first two numbers together can describe the kernel family. Like the stable version of 2.6.0, it is the 2.6 version of the kernel family. 128: This is the current version of the 5th fine-tuning patch, and elsmp points out that the current kernel is specially tuned for elsmp el:enterprise Linux; SMP: Indicates support for multiple processors, indicating that the kernel version supports multiprocessor

ELSMP and El and SMP in the Linux kernel
Under Linux ELSMP points out that the current kernel is a specially tuned el:enterprise Linux for ELSMP; SMP: Indicates support for multiple processors, which means that the kernel version supports multiprocessor

Example 2:red Hat Linux when booting up, the Grub boot menu will have two options, namely Red Hat Enterprise Linux ES (version number). ELSMP) Red Hat Enterprise Linux es-up (version number. EL) In fact, this is the system boot from grub booting-the difference between a single processor and a symmetric multiprocessor boot core file. Red Hat Enterprise Linux ES (version number. ELSMP) Multiple processor (symmetric multiprocessing) Red Hat Enterprise Linux es-up (version number. EL) uniprocessor

Number of Linux bits
We know that the current CPU is mainly divided into 32-bit and 64-bit, of which 32 bits can be divided into: i386, i586, i686, and 64 of the CPU is called x86_64, this is because different levels of CPU command set is not the same, so some of your software may be some of your CPU optimization, So the software has i386, i586, i686 and x86_64 of the points, in the current CPU market, most are sticking to the 64-bit software.

Linux kernel version