February 19, 2019

The Linux 2.6 Kernel: Cracking the Code

What is the Linux Kernel?

  • June 23, 2006
  • By Sean Michael Kerner

You could say the Linux kernel is on the cusp of adulthood--like a teenager about to reach voting age.

But in actuality, the kernel, now at version 2.6.17, has been at the heart of a rapid growth for the Linux open source operating system, from its early days helping to run less-important edge servers to now supporting mission-critical applications.

In this special report on the Linux kernel, LinuxPlanet summarizes the activity, its origins and where its going, in order to help readers gain a deeper understanding of the kernel, as well as Linux.

The kernel is perhaps the key defining aspect of the technological phenomenon we commonly refer to as "Linux."

In IT terms, a kernel is both the heart and brains of an operating system as it controls the underlying hardware.

A kernel is the core of an operating system and contains much of the root functions, such as virtual memory, multitasking, shared libraries, demand loading, shared copy-on-write executables and TCP/IP networking.

The Linux kernel dates back to 1991 when Finnish student Linus Torvalds wrote and first published.

Though the Linux ecosystem has grown far beyond Mr.Torvalds himself, to this day, Torvalds retains stewardship over the Linux kernel and is the sole copyright holder to the Linux name itself. Since the 0.12 release of the Linux kernel it has been licensed under the GPL Free Software license.

The Linux kernel is not an operating system itself. It is, however, a component (albeit a critical one) of a complete operating system.

Linux distributors, such as Red Hat, Novell, Debian, and Gentoo, all use a Linux kernel and then package in more tools, libraries and applications to create a complete operating system.

But the plain vanilla kernel.org Linus Torvalds co-developed is not necessarily the same kernel that the Linux distributions themselves will use.

Typically, a distribution company will customize the base kernel somewhat to its own needs and in some cases, distributions will include features or support in its own customized Linux kernel if they're not in the mainline kernel.

Such a case happened with Red Hat when it backported features�from the 2.6 kernel into its own 2.4.x kernel.

(The Ubuntu Linux distributions has just recently added support for Sun's 'Niagara' chips in the Ubuntu flavor of the 2.6.15 Linux kernel even though that support is not yet in the mainline kernel.)

Although backporting sprouted legs as an issue in the open source world, Torvalds keeps an open mind about it.

In 2004, he told JupiterWeb site internetnews.com in an e-mail interview that he supported the process of backporting.

"I think it makes sense from a company standpoint to basically 'cherry-pick' stuff from the development version that they feel is important to their customers," Torvalds wrote.

"And in that sense I think the back-porting is actually a very good thing."

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