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Encyclopedia > Linux kernel
Linux
Tux

Running Linux Kernel 2.6.11, Knoppix 3.8 booting
Author: Linus Torvalds
Developer: Linus Torvalds (author) and many others
Initial release: 1991
Latest release: 2.6.23.8 / 16 November 2007[1]
Preview release: 2.6.24-rc3 / 17 November 2007[2]
Programming language(s): C
OS: Linux
Genre: Kernel
License: GNU General Public License
Website: http://kernel.org/

The Linux kernel is a Unix-like operating system kernel. It is the namesake of the Linux family of operating systems. Released under the GNU General Public License (GPL) and developed by contributors worldwide, Linux is one of the most prominent examples of free software / open source.[3] Image File history File links NewTux. ... Image File history File links Knoppix-3. ... Knoppix, or KNOPPIX, is a complete Linux distribution on a CD. This includes a working computer operating system and a powerful suite of graphical user software which can be used as a live CD. It is a Debian-based Linux distribution, developed by Linux consultant Klaus Knopper. ... Software design is the process that starts from a problem for which there is currently no acceptable (software) solution, and ends when such a solution has been created. ... Linus Benedict Torvalds  ; born December 28, 1969 in Helsinki, Finland, is a Finnish software engineer best known for initiating the development of the Linux kernel. ... “Software development” redirects here. ... Linus Benedict Torvalds  ; born December 28, 1969 in Helsinki, Finland, is a Finnish software engineer best known for initiating the development of the Linux kernel. ... Year 1991 (MCMXCI) was a common year starting on Tuesday (link will display the 1991 Gregorian calendar). ... Code complete redirects here. ... is the 320th day of the year (321st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... Code complete redirects here. ... 17 November is also the name of a Marxist group in Greece, coinciding with the anniversary of the Athens Polytechnic uprising. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... A programming language is an artificial language that can be used to control the behavior of a machine, particularly a computer. ... C is a general-purpose, block structured, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ... An operating system (OS) is the software that manages the sharing of the resources of a computer and provides programmers with an interface used to access those resources. ... This article is about operating systems that use the Linux kernel. ... Computer software can be organized into categories based on common function, type, or field of use. ... A kernel connects the application software to the hardware of a computer. ... A software license is a legal agreement which may take the form of a proprietary or gratuitous license as well as a memorandum of contract between a producer and a user of computer software. ... GPL redirects here. ... A website (alternatively, Web site or web site) is a collection of Web pages, images, videos or other digital assets that is hosted on one or several Web server(s), usually accessible via the Internet, cell phone or a LAN. A Web page is a document, typically written in HTML... Diagram of the relationships between several Unix-like systems A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ... A kernel connects the application software to the hardware of a computer. ... This article is about operating systems that use the Linux kernel. ... GPL redirects here. ... Free software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions only to ensure that further recipients can also do these things. ... Open source software is computer software which source code is available under a license (or arrangement such as the public domain) that meets the Open_source_definition. ...


Linux was written by Linus Torvalds in 1991. Early on, the Minix community contributed code and ideas to the Linux kernel. At the time, the GNU Project had created many of the components required for a free software operating system, but its own kernel, GNU Hurd, was incomplete and unavailable. The BSD operating system had not yet freed itself from legal encumbrances. This meant that despite the limited functionality of the early versions, Linux rapidly accumulated developers and users who adopted code from those projects for use with the new operating system.[4] Today the Linux kernel has received contributions from thousands of programmers. Linus Benedict Torvalds  ; born December 28, 1969 in Helsinki, Finland, is a Finnish software engineer best known for initiating the development of the Linux kernel. ... MINIX is a free/open source, Unix-like operating system (OS) based on a microkernel architecture. ... The GNU logo, drawn by Etienne Suvasa The GNU Project was announced in 1983 by Richard Stallman. ... Free software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions only to ensure that further recipients can also do these things. ... “hurd” redirects here. ... BSD redirects here. ...

Part of a series on
Tux the Penguin
Linux
History
GNU ProjectLinux kernel (historyportability)Naming controversyWindows and LinuxAdoptionLinus's LawTux • SCO and Linux
Distribution
Linux distribution (listcomparison)Linux package formatsLiveDistro (listcomparison)Live USBMini Linux
Applications
LAMPDesktopEmbeddedGamingThin client
Legal bodies
Linux FoundationLinux Users' Group (LUG)
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Contents

Image File history File links Tux. ... This article is about operating systems that use the Linux kernel. ... The GNU logo, drawn by Etienne Suvasa The GNU Project was announced in 1983 by Richard Stallman. ... The Linux kernel has been marked by constant growth throughout its history. ... Originally written for Intels i386 processor, very early in its history, the Linux Kernel was re-coded for easy portability. ... The GNU/Linux naming controversy is a dispute between members of the free and open source software community relating to the normative branding of the computer operating systems commonly referred to as Linux. ... For a broader comparison of closed source and Open Source software, see Comparison of open source and closed source. ... This article does not cite any references or sources. ... Linus Law can refer to two notions, both named after Linus Torvalds. ... Tux, as originally drawn by Larry Ewing Tux (also known as Tux the Penguin) is the official mascot of the Linux kernel. ... The SCO-Linux controversies are a series of legal and public disputes between the software company SCO Group (SCO) and various Linux vendors and users. ... A Linux distribution, often simply distribution or distro, is a member of the Linux family of Unix-like operating systems comprising the Linux kernel, the non-kernel parts of the GNU operating system, and assorted other software. ... This page provides general information about notable Linux distributions in the form of a categorized list. ... Technical variations include support for different hardware devices and systems or software package configurations. ... Linux package formats are the different file formats used to package software for various GNU/Linux distributions. ... Gnoppix 0. ... This is a large list of LiveDistros. ... LiveDistro is a generic term for an operating system distribution that is executed upon boot, without installation on a hard drive. ... A live USB is a USB flash drive containing a full operating system which can be booted from. ... The standard MiniLinux logo The term Mini Linux (or Mini Linux Distribution) refers to any Linux distribution that fits on memory card or a small number of floppies, usually one or two. ... The acronym LAMP refers to a solution stack of software, usually free software / open-source software, used to run dynamic Web sites or servers. ... Desktop Linux, also Linux on the desktop (LOTD) is the application of the GNU/Linux operating system on a desktop computer. ... Embedded Linux is a Linux based embedded operating system used in cell phones, personal digital assistants, media player handsets and other consumer electronics devices. ... Linux gaming refers to playing and developing games for Linux operating systems. ... Linux Terminal Server Project (LTSP) is an add-on package for Linux that allows many people to simultaneously use the same computer. ... The Linux Foundation (LF) is a nonprofit consortium dedicated to fostering the growth of Linux. ... A Linux User Group or Linux Users Group (LUG) is a private, generally non-profit or not-for-profit organization that provides support and/or education for Linux users, particularly for inexperienced users. ...

History

In April 1991, Linus Torvalds, then 21 years old, started working on some simple ideas for an operating system. He started with a task switcher in Intel 80386 assembly and a terminal driver. Then, on 25 August 1991, Torvalds posted to comp.os.minix: The Linux kernel has been marked by constant growth throughout its history. ... A context switch is the computing process of storing and restoring the state (context) of a CPU such that multiple processes can share a single CPU resource. ... The Intel386[1] is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 2007. ... Overview In Unix, a pseudo terminal is a kernel device pair that simulates an ordinary terminal but without the associated terminal hardware. ...

I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. This has been brewing since April, and is starting to get ready. I'd like any feedback on things people like/dislike in minix, as my OS resembles it somewhat (same physical layout of the file-system (due to practical reasons) among other things).


I've currently ported bash(1.08) and gcc(1.40), and things seem to work. This implies that I'll get something practical within a few months [...] Yes - it's free of any minix code, and it has a multi-threaded fs. It is NOT portable (uses 386 task switching etc), and it probably never will support anything other than AT-harddisks, as that's all I have :-(.


[...] It's mostly in C, but most people wouldn't call what I write C. It uses every conceivable feature of the 386 I could find, as it was also a project to teach me about the 386. As already mentioned, it uses a MMU, for both paging (not to disk yet) and segmentation. It's the segmentation that makes it REALLY 386 dependent (every task has a 64Mb segment for code & data - max 64 tasks in 4Gb. Anybody who needs more than 64Mb/task - tough cookies). [...] Some of my "C"-files (specifically mm.c) are almost as much assembler as C. [...] Unlike minix, I also happen to LIKE interrupts, so interrupts are handled without trying to hide the reason behind them.[5]

After that, many people contributed code to the project. By September 1991, Linux version 0.01 was released. It had 10,239 lines of code. In October 1991, Linux version 0.02 was released.[6]


In December 1991, Linux 0.11 was released. This version was the first to be self-hosted - Linux 0.11 could be compiled by a computer running Linux 0.11. When he released the next version, Torvalds adopted the GNU General Public License (GPL) over his previous self-drafted license, which did not permit commercial redistribution.[7] Self-hosting refers to the use of a computer program as part of the toolchain or operating system that produces new versions of that same program—for example, a compiler that can compile its own source code. ... GPL redirects here. ...


A newsgroup alt.os.linux was started, and on January 19, 1992, the first post to alt.os.linux was made.[8] On March 31, 1992, alt.os.linux became comp.os.linux.[9] is the 19th day of the year in the Gregorian calendar. ... Year 1992 (MCMXCII) was a leap year starting on Wednesday (link will display full 1992 Gregorian calendar). ... is the 90th day of the year (91st in leap years) in the Gregorian calendar. ... Year 1992 (MCMXCII) was a leap year starting on Wednesday (link will display full 1992 Gregorian calendar). ...


The X Window System was soon ported to Linux. In March 1992, Linux version 0.95 was the first to be capable of running X. This large version number jump (from 0.1x to 0.9x) was due to a feeling that a version 1.0 with no major missing pieces was imminent. However, this proved to be somewhat overoptimistic, and from 1993 to early 1994, 15 development versions of version 0.99 appeared. “X11” redirects here. ...


On March 14, 1994, Linux 1.0.0 was released, with 176,250 lines of code. In March 1995, Linux 1.2.0 was released (310,950 lines of code). is the 73rd day of the year (74th in leap years) in the Gregorian calendar. ... Year 1994 (MCMXCIV) The year 1994 was designated as the International Year of the Family and the International Year of the Sport and the Olympic Ideal by the United Nations. ...


Linus decided, on May 9, 1996, to adopt Tux the penguin as mascot for Linux. is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 1996 (MCMXCVI) was a leap year starting on Monday (link will display full 1996 Gregorian calendar). ... Tux, as originally drawn by Larry Ewing Tux (also known as Tux the Penguin) is the official mascot of the Linux kernel. ...


Version 2 of Linux, released on June 9, 1996, was a landmark. Strong development continued: June 9 is the 160th day of the year in the Gregorian calendar (161st in leap years), with 205 days remaining. ... Year 1996 (MCMXCVI) was a leap year starting on Monday (link will display full 1996 Gregorian calendar). ...

is the 25th day of the year in the Gregorian calendar. ... This article is about the year. ... is the 352nd day of the year (353rd in leap years) in the Gregorian calendar. ... This article is about the year. ... SAS 8 on an IBM mainframe, seen here via one of its user interfaces, classic 3270 emulation. ... is the 4th day of the year in the Gregorian calendar. ... Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... December 17 is the 351st day of the year (352nd in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ...

Pronunciation

In 1992, Torvalds explained how he pronounces the word Linux:

'li' is pronounced with a short [ee] sound: compare prInt, mInImal etc. 'nux' is also short, non-diphthong, like in pUt. It's partly due to minix: linux was just my working name for the thing, and as I wrote it to replace minix on my system, the result is what it is... linus' minix became linux.

Linus Torvalds, comp.os.linux newsgroup[10]

Torvalds has made available an audio sample which indicates his own pronunciation, in English and Swedish.[11][12] However, an interview from the 2001 documentary Revolution OS indicates that his preferred pronunciation has slightly changed.[13] Year 2001 (MMI) was a common year starting on Monday (link displays the 2001 Gregorian calendar). ... Promotional poster for two disc edition of Revolution OS Revolution OS is a documentary which traces the history of GNU, Linux, Free Software and the Open Source movement. ...


Many English speakers tend to pronounce the name as [ˈlɪnʊks] or [ˈlɪnəks].


Legal aspects

Licensing terms

Initially, Torvalds released Linux under a license which forbade any commercial exploitation. This was soon changed to the GNU General Public License (GPL). This license allows distribution and sale of possibly modified and unmodified versions of Linux but requires that all those copies be released under the same license and be accompanied by the complete corresponding source code. GPL redirects here. ...


Torvalds has described licensing Linux under the GPL as the "best thing I ever did."[14]


GPL version 3

Currently, Linux is licensed under version 2 of the GPL, and there is some controversy over how easily it could be changed to use later GPL versions such as the new version 3 (and whether this is desirable).[15] Torvalds himself specifically indicated upon the release of version 2.4.0 that his own code is only under version 2.[16] However, the terms of the GPL state that if no version is specified, then any version may be used, and Alan Cox pointed out that very few other Linux contributors have specified a particular version of the GPL.[17] One blogger concluded that around 40% of Linux code is specifically "GPL 2 or above", and another approximately 10% is "GPL" (with no version specified), making for about half of the kernel, put together.[18] In September of 2006, a survey of 29 key kernel programmers indicated 28 preferred GPLv2 to the then-current GPLv3 draft. Torvalds commented, "I think a number of outsiders...believed that I personally was just the odd man out, because I've been so publicly not a huge fan of the GPLv3."[19] Alan Cox at FOSS.IN/2005 Alan Cox (born 1968) is a computer programmer heavily involved in the development of the Linux kernel since its early days (1991). ...


Loadable Kernel Modules and firmware

It is debated whether Loadable Kernel Modules (LKMs) should be considered derivative works under copyright law, and thereby fall under the terms of the GPL. Torvalds has stated his belief that LKMs using only a limited, "public" subset of the kernel interfaces can sometimes be non-derived works, thus allowing some binary-only drivers and other LKMs that are not licensed under the GPL. Not all Linux contributors agree with this interpretation, however, and even Torvalds agrees that many LKMs are clearly derived works, and indeed he writes that "kernel modules ARE derivative 'by default'". On the other hand Torvalds has also said that "one gray area in particular is something like a driver that was originally written for another operating system (ie. clearly not a derived work of Linux in origin). [...] THAT is a gray area, and _that_ is the area where I personally believe that some modules may be considered to not be derived works simply because they weren't designed for Linux and don't depend on any special Linux behaviour."[20] Especially proprietary graphics drivers are heavily discussed. Ultimately, such questions can only be resolved by a court[dubious ]. In computing, loadable kernel modules, or LKM, are object files that contain code to extend the running kernel, or so-called base kernel, of an operating system. ... This montage of different images is an example of a derivative work In copyright law, a derivative work is an artistic creation that includes major, basic copyrighted aspects of an original, previously created first work. ... Proprietary software is software with restrictions on copying and modifying as enforced by the proprietor. ...


One point of licensing controversy is Linux's use of firmware "binary blobs" to support some hardware devices. Richard Stallman claims that these blobs make Linux partially non-free software, and that distributing Linux may even be violating the GPL (which requires "complete corresponding source code" to be available).[21] A microcontroller, like this PIC18F8720 is controlled by firmware stored inside on FLASH memory In computing, firmware is a computer program that is embedded in a hardware device, for example a microcontroller. ... In computing, a binary blob is an object file loaded into the kernel of a free or open source operating system without publicly available source code. ... Richard Matthew Stallman (born March 16, 1953), often abbreviated rms,[1] is an American software freedom activist, hacker,[2] and software developer. ... Proprietary software is a pejorative term used by the Free Software Foundation to describe software in which the user does not control what it does or cannot study or edit the code, in contrast to free software. ...


Trademark

Linux is a registered trademark of Linus Torvalds in the United States and some other countries. This is the result of an incident in which William Della Croce, Jr., who was not involved in the Linux project, trademarked the name and subsequently demanded royalties for its use. Several Linux backers retained legal counsel and filed suit against Della Croce, who agreed in 1998 to assign the trademark to Torvalds. “(TM)” redirects here. ... This article or section does not adequately cite its references or sources. ...


SCO litigation

For more details on this topic, see SCO-Linux controversies.

In March 2003, the SCO Group (SCO) filed a lawsuit against IBM claiming that IBM had violated copyrights that SCO claimed to hold over the Unix source code, by contributing portions of that code to Linux. Additionally, SCO sent letters to a number of companies warning that their use of Linux without a license from SCO may be a violation of copyright law, and claimed in the press that they would be suing individual Linux users. This controversy has generated lawsuits by SCO against Novell, DaimlerChrysler (partially dismissed in July, 2004), and AutoZone, and retaliatory lawsuits by Red Hat and others against SCO. The SCO-Linux controversies are a series of legal and public disputes between the software company SCO Group (SCO) and various Linux vendors and users. ... The SCO Group, Inc. ... SCO v. ... For other uses, see IBM (disambiguation) and Big Blue. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... Novell Inc. ... DaimlerChrysler AG (ISIN: DE0007100000) is a German car corporation and the worlds eighth largest car manufacturer. ... AutoZone NYSE: AZO is a Fortune 500 corporation based in Memphis, Tennessee which is engaged primarily in the business of the retail sale of automotive parts and accessories. ... For other uses, see Red Hat (disambiguation). ...


In early 2007 SCO filed the specific details of the purported copyright infringement. Despite previous claims that SCO was the rightful owner of 1 million lines of code, they specified only 326 lines of code, most of which were uncopyrightable [1]. In August 2007, the court in the Novell case ruled that SCO did not actually own the Unix copyrights to begin with. [2] SCO v. ...


Technical features

Linux supports true preemptive multitasking (both in user mode and kernel mode), virtual memory, shared libraries, demand loading, shared copy-on-write executables, memory management, the Internet protocol suite, and threading. In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is... User mode refers to two similar concepts in computer architecture. ... In processors with memory protection, kernel mode (as opposed to user mode) is the mode in which the operating system kernel runs. ... The program thinks it has a large range of contiguous addresses; but in reality the parts it is currently using are scattered around RAM, and the inactive parts are saved in a disk file. ... Illustration of an application which may use libvorbisfile. ... In computer operating systems, demand paging is an application of virtual memory. ... Copy-on-write (sometimes referred to as COW) is an optimization strategy used in computer programming. ... Memory management is the act of managing computer memory. ... The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. ... For the form of code consisting entirely of subroutine calls, see Threaded code. ...


Architecture

Simplified Linux kernel diagram in the form of a matrix map
Simplified Linux kernel diagram in the form of a matrix map

Linux is a monolithic kernel. Device drivers and kernel extensions run in kernel space (ring 0), with full access to the hardware, although some exceptions run in user space. Unlike Microsoft Windows, the graphics system most people use with Linux doesn't run in the kernel. Image File history File links Size of this preview: 800 × 598 pixelsFull resolution (1024 × 766 pixel, file size: 42 KB, MIME type: image/png) (All user names refer to en. ... Image File history File links Size of this preview: 800 × 598 pixelsFull resolution (1024 × 766 pixel, file size: 42 KB, MIME type: image/png) (All user names refer to en. ... It has been suggested that Monolithic system be merged into this article or section. ... A device driver, or software driver is a computer program allowing higher-level computer programs to interact with a computer hardware device. ... In computer engineering the kernel is the core of an operating system. ... In computer science, hierarchical protection domains, often called protection rings, are a mechanism to protect data and functionality from faults (fault tolerance) and malicious behaviour (computer security). ... An operating system usually segregates the available system memory into kernel space and user space. ... Windows redirects here. ... “X11” redirects here. ...


Kernel mode preemption allows device drivers to be preempted under certain conditions. This feature was added to handle hardware interrupts correctly and improve support for symmetric multiprocessing (SMP). Preemption also improves latency, increasing responsiveness and making Linux more suitable for real-time applications. In processors with memory protection, kernel mode (as opposed to user mode) is the mode in which the operating system kernel runs. ... Pre-emption as used with respect to operating systems means the ability of the operating system to preempt or stop a currently scheduled task in favour of a higher priority task. ... In computing, an interrupt is an asynchronous signal from hardware or software indicating the need for attention. ... Symmetric multiprocessing, or SMP, is a multiprocessor computer architecture where two or more identical processors are connected to a single shared main memory. ... Latency is a time delay between the moment something is initiated, and the moment one of its effects begins. ...


The fact that Linux is a monolithic kernel rather than a microkernel was the topic of the Tanenbaum-Torvalds debate[22] between Andrew S. Tanenbaum and Linus Torvalds. The debate started in 1992 about Linux and kernel architecture in general on the Usenet discussion group comp.os.minix.[23] Tanenbaum argued that microkernels are superior to monolithic kernels and that therefore Linux is obsolete. Unlike traditional monolithic kernels, device drivers are easily configured as Loadable Kernel Modules, and loaded or unloaded while running the system. This subject was revisited on 9 May 2006,[24] and on 12 May 2006 Tanenbaum authored a position statement.[25] Graphical overview of a microkernel A microkernel is a minimal computer operating system kernel providing only basic operating system services (system calls), while other services (commonly provided by kernels) are provided by user-space programs called servers. ... The Tanenbaum-Torvalds debate is a famous debate started in 1992 by Andrew S. Tanenbaum with Linus Torvalds regarding Linux and kernel architecture in general on Usenet discussion group comp. ... Andrew S. Tanenbaum Dr. Andrew Stuart Andy Tanenbaum (sometimes called ast)[1] (born 1944) is a professor of computer science at the Vrije Universiteit, Amsterdam in the Netherlands. ... Linus Benedict Torvalds  ; born December 28, 1969 in Helsinki, Finland, is a Finnish software engineer best known for initiating the development of the Linux kernel. ... Usenet (USEr NETwork) is a global, decentralized, distributed Internet discussion system that evolved from a general purpose UUCP architecture of the same name. ... This article is about operating systems that use the Linux kernel. ... Obsolescence is when a person or object is no longer wanted even though it is still in good working order. ... In computing, loadable kernel modules, or LKM, are object files that contain code to extend the running kernel, or so-called base kernel, of an operating system. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 132nd day of the year (133rd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...


Build Options

The Linux kernel has configurable Linux build options that enable specific features to be added or removed from the kernel during initial compilation. Customized default parameters may also be configured during the intial compilation. The Linux kernel has configurable build options that enable specific features to be added or removed from the kernel during initial compilation. ...


Kernel panic

Kernel Panic
Kernel Panic
Main article: Kernel panic

In Linux, a "panic" is an unrecoverable system error detected by the kernel as opposed to similar errors detected by user space code. It is possible for kernel code to indicate such a condition by calling the panic function located in the header file sys/system.h. However, most panics are the result of unhandled processor exceptions in kernel code, such as references to invalid memory addresses. These are typically indicative of a bug somewhere in the call chain leading to the panic. They can also indicate a failure of hardware, such as a failed RAM cell or errors in arithmetic functions in the processor caused by a processor bug, overheating/damaged processor, or a soft error. Image File history File links Metadata Size of this preview: 800 × 533 pixelsFull resolution‎ (2,560 × 1,706 pixels, file size: 999 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Metadata Size of this preview: 800 × 533 pixelsFull resolution‎ (2,560 × 1,706 pixels, file size: 999 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Linux kernel panic under QEMU. Mac OS X kernel panic alert. ... An operating system usually segregates the available system memory into kernel space and user space. ... Exception handling is a programming language construct or computer hardware mechanism designed to handle the occurrence of some condition that changes the normal flow of execution. ... A computer bug is an error, flaw, mistake, failure, or fault in a computer program that prevents it from working as intended, or produces an incorrect result. ... On October 30, 1994, Professor Thomas Nicely who was then at Lynchburg College reported a bug in the Pentium floating point unit. ... In electronics and computing, an error is a signal or datum which is wrong. ...


Programming languages

Linux is written in the version of the C programming language supported by GCC (which has introduced a number of extensions and changes to standard C), together with a number of short sections of code written in the assembly language (in GCC's "AT&T-style" syntax) of the target architecture. Because of the extensions to C it supports, GCC was for a long time the only compiler capable of correctly building Linux. Recently, Intel claims to have modified its C compiler so that it is also capable of correctly compiling it.[26] C is a general-purpose, block structured, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ... The GNU Compiler Collection (usually shortened to GCC) is a set of programming language compilers produced by the GNU Project. ... See the terminology section, below, regarding inconsistent use of the terms assembly and assembler. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ...


Many other languages are used in some way, primarily in connection with the kernel build process (the methods whereby the bootable image is created from the sources). These include Perl, Python, and various shell scripting languages. Some drivers may also be written in C++, Fortran, or other languages, but this is strongly discouraged. Linux's build system only officially supports GCC as a kernel and driver compiler. In the field of computer software, the term software build refers either to the process of converting source code files into executable code or the result of doing so. ... Wikibooks has a book on the topic of Perl Programming Perl is a dynamic programming language created by Larry Wall and first released in 1987. ... Python is a high-level programming language first released by Guido van Rossum in 1991. ... A shell script is a script written for the shell, or command line interpreter, of an operating system. ... C++ (pronounced see plus plus, IPA: ) is a general-purpose programming language with high-level and low-level capabilities. ... Fortran (previously FORTRAN[1]) is a general-purpose[2], procedural,[3] imperative programming language that is especially suited to numeric computation and scientific computing. ...


Portability

Ipod linux booting kernel
Ipod linux booting kernel

While not originally designed to be portable, Linux is now one of the most widely ported operating system kernels, running on a diverse range of systems from the iPAQ (a handheld computer) to the IBM System z9 (a massive mainframe server that can run hundreds or even thousands of concurrent Linux instances). Linux runs as the main operating system on IBM's Blue Gene supercomputers. As of June 2007, Linux is the OS on more than 75% of systems on the Top 500 supercomputers list.[27] Image File history File links Size of this preview: 526 × 600 pixelsFull resolution‎ (700 × 798 pixels, file size: 286 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image File history File links Size of this preview: 526 × 600 pixelsFull resolution‎ (700 × 798 pixels, file size: 286 KB, MIME type: image/jpeg) File historyClick on a date/time to view the file as it appeared at that time. ... Image:IPodLinux. ... Originally written for Intels i386 processor, very early in its history, the Linux Kernel was re-coded for easy portability. ... In computer science, porting is the process of adapting software so that an executable program can be created for a computing environment that is different from the one for which it was originally designed (e. ... iPAQ presently refers to a Pocket PC and personal digital assistant first unveiled by Compaq in April 2000; the name was borrowed from Compaqs earlier iPAQ Desktop Personal Computers. ... IBM System z9 System z9 is the newest and most powerful line of IBM mainframes. ... For other uses, see Mainframe. ... This article is about the supercomputer. ... For other uses, see Supercomputer (disambiguation). ... 2007 is a common year starting on Monday of the Gregorian calendar. ...


Virtual machine architectures

See Comparison of virtual machines for more details on product support for Linux.
See Hypervisor for more details on terminology used with virtual machines.

The Linux kernel has extensive support for and runs on many virtual machine architectures both as the host operating system and as a client operating system. The virtual machines usually emulate Intel x86 family of processors, though in a few cases PowerPC or AMD processors are also emulated. The table below compares basic information about virtual machine packages. ... In computing, a hypervisor (also: virtual machine monitor) is a virtualization platform that allows multiple operating systems to run on a host computer at the same time. ... In general terms, a virtual machine in computer science is software that creates an environment between the computer platform and the end user in which the end user can operate software. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... PowerPC is a RISC microprocessor architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM. Originally intended for personal computers, PowerPC CPUs have since become popular embedded and high-performance processors as well. ... Advanced Micro Devices, Inc. ...


Supported binary formats

Linux 1.0 supported only the a.out binary format. The next stable series (Linux 1.2) added support for Executable and Linkable Format (ELF), which simplifies the creation of shared libraries (used extensively by modern desktop environments like KDE and GNOME[28]). ELF is the default format used by gcc since around gcc 2.7.0[29], so a.out is now rarely if ever used, and ELF is now the primary binary format. a. ... In computing, the Executable and Linking Format (ELF, formerly called Extensible Linking Format) is a common standard file format for executables, object code, shared libraries, and core dumps. ... In computer science, a library is a collection of subprograms used to develop software. ... Information in this article or section has not been verified against sources and may not be reliable. ... For the NYSE stock ticker symbol KDE, see 4Kids Entertainment. ... This article is about the mythical creature. ... The GNU Compiler Collection (usually shortened to GCC) is a set of programming language compilers produced by the GNU Project. ...


Linux supports many other binary formats, including binfmt misc for associating files to a program (such as an interpreter) to run or display that file. binfmt_misc is a Linux kernel capability which allows arbitrary executable file formats to be recognized and passed to certain user space applications, such as emulators and virtual machines. ... In computer science, an interpreter is a computer program that executes, or performs, instructions written in a computer programming language. ...


Estimated cost to redevelop

The cost to redevelop the Linux kernel version 2.6.0 in a traditional proprietary development setting has been estimated to be US$612M (467M €) in 2004 prices using the COCOMO man-month estimation model.[30] In 2006, a study funded by the European Union put the redevelopment cost of kernel version 2.6.8 significantly higher, to 882M € (US$1.14B).[31] This article or section is in need of attention from an expert on the subject. ...


Versions

Further developing his own code and integrating changes made by other programmers, Linus Torvalds keeps releasing new versions of the Linux kernel. These are called "vanilla" kernels, meaning they have not been further modified by anyone. Many Linux operating system vendors modify the kernels of their product, mainly in order to add support for drivers or features which have not officially been released as stable, while some distributions rely on vanilla kernels.


Version numbering

The version number of the Linux kernel currently consists of four numbers, following a recent change in the long-standing policy of a three-number versioning scheme. For illustration, let it be assumed that the version number is composed thus: A.B.C[.D] (e.g. 2.2.1, 2.4.13 or 2.6.12.3).

  • The A number denotes the kernel version. It is changed least frequently, and only when major changes in the code and the concept of the kernel occur. It has been changed twice in the history of the kernel: In 1994 (version 1.0) and in 1996 (version 2.0).
  • The B number denotes the major revision of the kernel.
    • Prior to the Linux 2.6.x series, even numbers indicate a stable release, i.e. one that is deemed fit for production use, such as 1.2, 2.4 or 2.6. Odd numbers have historically been development releases, such as 1.1 or 2.5. They were for testing new features and drivers until they became sufficiently stable to be included in a stable release.
    • Starting with the Linux 2.6.x series, there is no significance to even or odd numbers, with new feature development going on in the same kernel series. Linus Torvalds has stated that this will be the model for the foreseeable future.
  • The C number indicates the minor revision of the kernel. In the old three-number versioning scheme, this was changed when security patches, bugfixes, new features or drivers were implemented in the kernel. With the new policy, however, it is only changed when new drivers or features are introduced; minor fixes are handled by the D number.
  • A D number first occurred when a grave error, which required immediate fixing, was encountered in 2.6.8's NFS code. However, there were not enough other changes to legitimize the release of a new minor revision (which would have been 2.6.9). So, 2.6.8.1 was released, with the only change being the fix of that error. With 2.6.11, this was adopted as the new official versioning policy. Bug-fixes and security patches are now managed by the fourth number, whereas bigger changes are only implemented in minor revision changes (the C number).

Also, sometimes after the version there will be some more letters such as 'rc1' or 'mm2'. The 'rc' refers to release candidate and indicates a non-official release. Other letters are usually (but not always) the initials of a person. This indicates a development branch of the kernel by that person. e.g. ck stands for Con Kolivas, ac stands for Alan Cox, whereas mm stood for Andrew Morton. In mathematics, the parity of an object refers to whether it is even or odd. ... In mathematics, the parity of an object refers to whether it is even or odd. ... Network File System (NFS) is a network file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network as easily as if the network devices were attached to its local disks. ... It has been suggested that this article or section be merged with Development stage#Release candidate. ... In software engineering, a project fork or branch happens when a developer (or a group of them) takes a copy of source code from one software package and starts to independently develop a new package. ... Con Kolivas is practicing doctor in Australia but he is known for the work done on the Linux kernel in his spare time. ... Alan Cox at FOSS.IN/2005 Alan Cox (born 1968) is a computer programmer heavily involved in the development of the Linux kernel since its early days (1991). ... Andrew Morton is a Linux kernel developer. ...


The development model for Linux 2.6 was a significant change from the development model for Linux 2.5. Previously there was a stable branch (2.4) where only relatively minor and safe changes were merged, and an unstable branch (2.5), where bigger changes and cleanups were allowed. This meant that users would always have a well-tested 2.4 version with the latest security and bug fixes to use, though they would have to wait for the features which went into the 2.5 branch. The downside of this was that the "stable" kernel ended up so far behind that it no longer supported recent hardware and lacked needed features. In the late 2.5.x series kernel some maintainers elected to try and backport their changes to the stable series kernel which resulted in bugs being introduced into the 2.4.x series kernel. The 2.5 branch was then eventually declared stable and renamed to 2.6. But instead of opening an unstable 2.7 branch, the kernel developers elected to continue putting major changes into the 2.6 "stable" branch. This had the desirable effect of breaking changes into smaller and easier to test batches, making new features quickly available, and getting more testing of the latest code.


However, the new 2.6 development model also meant that there was no stable branch for people just wanting security and bug fixes, and not needing the latest features. Fixes were only put into the latest version, so if a user wanted a version with all known bugs fixed they would also get all the latest features, which had not been well tested, and risked breaking things which had previously worked. A partial fix for this was the previously mentioned fourth version number digit (y in 2.6.x.y), which are series of point releases created by the stable team (Greg Kroah-Hartman, Chris Wright, maybe others). The stable team only released updates for the most recent kernel however, so this did not solve the problem of the missing stable kernel series. Linux distribution vendors, such as Red Hat and Debian, maintain the kernels which ship with their releases, so a solution for some people is to just follow a vendor kernel. Greg Kroah-Hartman is a Linux kernel hacker. ... Chris Wright may refer to: Chris Wright (cricketer), of Middlesex County Cricket Club Chris Wright (footballer), of Boston United F.C. C.W. Anderson, wrestler Category: ... A Linux distribution, often simply distribution or distro, is a member of the Linux family of Unix-like operating systems comprising the Linux kernel, the non-kernel parts of the GNU operating system, and assorted other software. ... For other uses, see Red Hat (disambiguation). ... Debian is a free operating system. ...


As a response to the lack of a stable kernel tree where people could coordinate the collection of bugfixes, in December of 2005 Adrian Bunk announced that he would keep releasing 2.6.16.y kernels when the stable team moved on to 2.6.17 [3]. He also plans to include driver updates, making the maintenance of the 2.6.16 series very similar to the old rules for maintenance of a stable series such as 2.4 [4].


As of November 18, 2007, the latest stable kernel version is 2.6.23.8.


Maintenance

While Linus Torvalds supervises code changes and releases to the latest kernel versions, he has delegated the maintenance of older versions to other programmers:

Kernel series Maintainer
2.0 David Weinehall[32]
2.2 Marc-Christian Petersen[33] (former maintainer Alan Cox)
2.4 Willy Tarreau[34] (former maintainer Marcelo Tosatti)
2.6.16 Adrian Bunk[35]
2.6 Andrew Morton / Linus Torvalds

Other Linux kernel programmers include Robert Love and Ingo Molnar.[36] Alan Cox at FOSS.IN/2005 Alan Cox (born 1968) is a computer programmer heavily involved in the development of the Linux kernel since its early days (1991). ... Marcelo Tosatti in Porto Alegre, April 2006. ... Andrew Morton is a Linux kernel developer. ... Linus Benedict Torvalds  ; born December 28, 1969 in Helsinki, Finland, is a Finnish software engineer best known for initiating the development of the Linux kernel. ... Robert Love with a piñata Robert Matthew Love (born September 25, 1981) is an author, speaker, and open source hacker. ... Ingo Molnár, currently employed by Red Hat, is a Hungarian Linux kernel hacker. ...


As of 2007, the kernel source code is maintained by Git, a source code control system created by Linus Torvalds. Git is a distributed revision control / software configuration management project created by Linus Torvalds to manage software development of the Linux kernel. ...


Stable version history

  • Version 1.0 of March 1994 supported only single-processor i386 machines.
  • Version 1.2 of March 1995 added support for Alpha, Sparc and MIPS.
  • Version 2.0 of June 1996 included SMP support and added support for more types of processors.
  • Version 2.2 of January 1999 (The Wonderful World of Linux 2.2).
  • Version 2.6 - current (December 17, 2003 to the present)[38]
    • integrated µClinux (for microcontrollers) [citation needed]
    • CPU support: with support for Hitachi's H8/300 series, the NEC v850, and Motorola's embedded m68k processors, NUMA support, support for NCR's Voyager architecture, support for Intel's hyperthreading and Physical Address Extension (PAE)
    • integrated the ALSA sound driver
    • OS support:
      • Improved APIC support.
      • Increased the maximum number of users and groups each from 65,536 (= 216) to 4,294,967,296 (232).
      • Increased the maximum number of process ids from 32,768 (= 215) to 1,073,741,824 (230).
      • Increased the maximum number of device types (major device) from 255 to 4095 and the maximum number of devices of each type (minor device) from 255 to more than a million.
      • Improved 64-bit support and filesystems of up to 16 terabytes on common hardware.
      • Improvements to the "overall responsiveness" for interactive processes (the kernel became fully pre-emptible and the I/O scheduler was rewritten).
      • Support for futexes, a rewrite of threading infrastructure to allow the Native POSIX Thread Library (NPTL) to be used.
      • An improved module loader.
      • User-mode Linux integration.
      • 2.6.11 Infiniband support
    • Storage Support:
      • LVM version 2
      • support for SGI's XFS filesystem.
      • A new "system filesystem" called sysfs, destined to relieve procfs of its system related information.
      • 2.6.2 ATA over Ethernet support
      • 2.6.12 (17 June 2005) iSCSI support
      • 2.6.13 inotify support
      • 2.6.14 9P support
      • 2.6.14 FUSE support
      • 2.6.17 Online reshaping of software raid5/6

Symmetric multiprocessing, or SMP, is a multiprocessor computer architecture where two or more identical processors are connected to a single shared main memory. ... The Hewlett-Packard Company (NYSE: HPQ), commonly known as HP, is a very large, global company headquartered in Palo Alto, California, United States. ... PA-RISC is a microprocessor architecture developed by Hewlett-Packards Systems & VLSI Technology Operation. ... Axiss products include this webcam, which can be connected directly to a network or the internet, via an RJ45 connector on its rear. ... An ETRAX FS chip The ETRAX CRIS is a series of CPUs designed and manufactured by Axis Communications for use in embedded systems since 1993[1]. The name is an acronim of the chips features: Ethernet, Token Ring, AXis - Code Reduced Instruction Set. ... This article does not cite any references or sources. ... Plug and Play is a term used in the computer field to describe a computers ability to have new devices, normally peripherals, added to it without having to restart the computer. ... USB redirects here. ... The PCMCIA is the Personal Computer Memory Card International Association, an industry trade association that creates standards for notebook computer peripheral devices. ... Bluetooth logo This article is about the electronic protocol named after Harald Bluetooth Gormson. ... LVM is an implementation of a logical volume manager for the Linux kernel. ... In computing, a redundant array of inexpensive disks, also later known as redundant array of independent disks (commonly abbreviated RAID) is a system which uses multiple hard drives to share or replicate data among the drives. ... InterMezzo is a distributed file system written for Linux, distributed with a GPL licence. ... December 17 is the 351st day of the year (352nd in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... µClinux (which stands for MicroControllerLinux and is pronounced as you-see-Linux) is a Linux distro operating system for microcontrollers (µCs, embedded systems) without a memory management unit (MMU). ... It has been suggested that this article or section be merged with embedded microprocessor. ... It has been suggested that Hitachi Works be merged into this article or section. ... H8 is the name of a large family of 8-bit and 16-bit microcontrollers made by Renesas Technology Corp. ... NEC Corporation (Jp. ... The NEC Electronics Corporation V850 is a 32-bit embedded RISC microcontroller originally developed and manufactured by NEC, succeeded by V850 variants named V850E, and V850E2 which run uClinux, and is supported by GNU_Compiler_Collection. ... Motorola Inc. ... The Motorola 680x0, 0x0, m68k, or 68k family of CISC microprocessor CPU chips were 32-bit from the start, and were the primary competition for the Intel x86 family of chips. ... Non-Uniform Memory Access or Non-Uniform Memory Architecture (NUMA) is a computer memory design used in multiprocessors, where the memory access time depends on the memory location relative to a processor. ... NCR Corporation (NYSE: NCR) is a technology company specializing in solutions for the retail and financial industries. ... The NCR Voyager was an SMP computer platform produced by the NCR Corporation. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... Hyper-Threading (HTT = Hyper Threading Technology) is Intels trademark for their implementation of the simultaneous multithreading technology on the Pentium 4 microarchitecture. ... In computing, Physical Address Extension (PAE) refers to a feature of x86 processors that allows for up to 64 gigabytes of physical memory to be used in 32-bit systems, given appropriate operating system support. ... A screenshot of alsamixer ALSA (an acronym for Advanced Linux Sound Architecture) is a Linux kernel component intended to replace the original Open Sound System (OSS) for providing drivers for sound cards. ... The Intel APIC Architecture is a system of Advanced Programmable Interrupt Controllers (APICs) designed by Intel for use in Symmetric Multi-Processor (SMP) computer systems. ... See Filing system for this term as it is used in libraries and offices In computing, a file system is a method for storing and organizing computer files and the data they contain to make it easy to find and access them. ... This article is about a measurement term for data storage capacity. ... Pre-emption as used with respect to operating systems means the ability of the operating system to preempt or stop a currently scheduled task in favour of a higher priority task. ... I/O Scheduling which should not be confused with process scheduling. ... A futex (short for fast userspace mutex) is a basic tool to realize locking and building higher-level locking abstractions such as semaphores and POSIX mutexes on Linux. ... In the GNU/Linux operating system, the Native POSIX Thread Library (NPTL) is a software feature that enables the Linux kernel to run programs written to use POSIX Threads fairly efficiently. ... User-mode Linux (UML) allows multiple virtual Linux systems (known as guests) to run as an application within a normal Linux system (known as the host). ... The panel of an InfiniBand switch InfiniBand is a switched fabric communications link primarily used in high-performance computing. ... Silicon Graphics, Inc. ... XFS is a high-performance journaling file system created by Silicon Graphics for their IRIX operating system. ... Sysfs is a virtual file system provided by the 2. ... On Unix-like computer systems, procfs is short for process filesystem: a pseudo-filesystem which is used to access kernel information about processes. ... ATA over Ethernet (AoE) is a network protocol developed by Coraid, Inc. ... is the 168th day of the year (169th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... iSCSI is a protocol that allows clients (called initiators) to send SCSI commands (CDBs) to SCSI storage devices (targets) on remote servers. ... inotify is a Linux kernel subsystem that provides file system event notification. ... Client and server implementations of the 9P distributed file system protocol for Unix-based operating systems. ... Filesystem in Userspace (FUSE) is a Free (GPL and LGPLed) Unix kernel module that allows non-privileged users to create their own file systems without the need to write any kernel code. ...

See also

Free software Portal

Image File history File links Free_Software_Portal_Logo. ... menuconfig for a 2. ...

References

  1. ^ Greg Kroah-Hartman (16 November 2007). Linux 2.6.23.8.
  2. ^ Linus Torvalds (17 November 2007). Linux 2.6.24-rc3.
  3. ^ Linus Torvalds (2006-09-25). Re: GPLv3 Position Statement.
  4. ^ Free as in Freedom by Sam Williams. O'Reilly books, 2002
  5. ^ "What would you like to see most in minix?". comp.os.minix. (Web link).
  6. ^ "Free minix-like kernel sources for 386-AT". comp.os.minix. (Web link).
  7. ^ Torvalds, Linus. Release Notes for Linux v0.12. The Linux Kernel Archives. Retrieved on 2007-02-21.
  8. ^ (19 January 1992). "Troubles with Partitions". comp.os.minix. (Web link). Retrieved on 2007-01-07.
  9. ^ (31 March 1992). "It's here!". comp.os.linux. (Web link). Retrieved on 2007-01-07.
  10. ^ (23 April 1992). "Re: How to pronounce "Linux"?". (Google Groups). Retrieved on 2007-01-09.
  11. ^ Howto pronouce Linux?. Retrieved on 2006-12-17.
  12. ^ Linus pronouncing Linux in English and Swedish. Retrieved on 2007-01-20.
  13. ^ Linux Pronunciation (Youtube). Retrieved on 2007-01-20.
  14. ^ Yamagata, Hiroo (1997). The Pragmatist of Free Software. HotWired. Retrieved on 2007-02-21.
  15. ^ Corbet, Jonathan (2006-01-31). GPLv3 and the kernel. LWN.net. Retrieved on 2007-02-21.
  16. ^ Torvalds, Linus (2000-09-08). Linux-2.4.0-test8. Linux-kernel mailing list archive. Unix Systems Support Group of Indiana University. Retrieved on 2007-02-21.
  17. ^ Cox, Alan (2006-01-20). Re: GPL V3 and Linux. Linux-kernel mailing list archive. LWN.net. Retrieved on 2007-02-21.
  18. ^ How much Linux Kernel code is GPL 2 only?. Software Geopolitics. Blogspot. Retrieved on 2007-02-21.
  19. ^ Shankland, Stephen (September 25, 2006). Top Linux programmers pan GPL 3. News.com. Retrieved on 2007-02-21.
  20. ^ Re: Linux GPL and binary module exception clause?
  21. ^ Stallman, Richard (2006-10-11). Linux, GNU, and freedom. Free Software Foundation. Retrieved on 2007-02-21.
  22. ^ O'Reilly (1999). The Tanenbaum-Torvalds Debate. O'Reilly. Retrieved on 2006-11-22.
  23. ^ (29 January 1992). "LINUX is obsolete". comp.os.minix. (Web link). Retrieved on 2006-05-10.
  24. ^ Torvalds, Linus (9 May 2006). Hybrid kernel, not NT. Retrieved on 2007-01-06.
  25. ^ Tanenbaum, Andy (12 May 2006). Tanenbaum-Torvalds Debate: Part II. Retrieved on 2007-01-06.
  26. ^ Linux kernel patch for Intel® Compiler
  27. ^ Operating system Family. Top 500 Supercomputer Sites (June 2007).
  28. ^ ldd /usr/bin/kwin lists 40 shared libraries (kwin 3.5.5a); ldd /usr/bin/gnome-panel lists 68 (gnome-panel 2.14.3).
  29. ^ Barlow, Daniel (1995-09-13). The Linux ELF HOWTO. Retrieved on 2007-07-19.
  30. ^ David A. Wheeler. Linux Kernel 2.6: It's Worth More!.
  31. ^ Economic impact of FLOSS on innovation and competitiveness of the EU ICT sector, Table 3 on page 50.
  32. ^ David Weinehall (2004-02-08). [ANNOUNCE] Linux-kernel 2.0.40 aka ``The Moss-covered Tortoise''.
  33. ^ Marc-Christian Petersen (2005-01-13). Linux 2.2.27-rc2.
  34. ^ Willy Tarreau (2007-07-26). Linux 2.4.35 released. linux-kernel mailing list.
  35. ^ Adrian Bunk (2007-03-36). Linux 2.6.16.45. linux-kernel mailing list.
  36. ^ See the Linux MAINTAINERS file.
  37. ^ Wonderful World of Linux 2.4
  38. ^ The Wonderful World of Linux 2.6

Just for Fun: The Story of an Accidental Revolutionary is a humorous biography of Linus Torvalds, the creator of Linux, co-written with David Diamond. ... is the 289th day of the year (290th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... In computing, diff is a file comparison utility that outputs the differences between two files. ... is the 320th day of the year (321st in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... 17 November is also the name of a Marxist group in Greece, coinciding with the anniversary of the Athens Polytechnic uprising. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 268th day of the year (269th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 52nd day of the year in the Gregorian calendar. ... is the 19th day of the year in the Gregorian calendar. ... Year 1992 (MCMXCII) was a leap year starting on Wednesday (link will display full 1992 Gregorian calendar). ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 7th day of the year in the Gregorian calendar. ... is the 90th day of the year (91st in leap years) in the Gregorian calendar. ... Year 1992 (MCMXCII) was a leap year starting on Wednesday (link will display full 1992 Gregorian calendar). ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 7th day of the year in the Gregorian calendar. ... is the 113th day of the year (114th in leap years) in the Gregorian calendar. ... Year 1992 (MCMXCII) was a leap year starting on Wednesday (link will display full 1992 Gregorian calendar). ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 9th day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... December 17 is the 351st day of the year (352nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 20th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 20th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 52nd day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 31st day of the year in the Gregorian calendar. ... LWN.net is a computing news site with an emphasis on Free/Libre/Open-Source Software and software for Unix-like operating systems. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 52nd day of the year in the Gregorian calendar. ... Year 2000 (MM) was a leap year starting on Saturday (link will display full 2000 Gregorian calendar). ... is the 251st day of the year (252nd in leap years) in the Gregorian calendar. ... Indiana University, founded in 1820, is a nine-campus university system in the state of Indiana. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 52nd day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 20th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 52nd day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 52nd day of the year in the Gregorian calendar. ... is the 268th day of the year (269th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... CNET Networks Inc. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 52nd day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 284th day of the year (285th in leap years) in the Gregorian calendar. ... The Free Software Foundation (FSF) is a non-profit corporation founded in October 1985 by Richard Stallman to support the free software movement (free as in freedom), and in particular the GNU project. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 52nd day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 326th day of the year (327th in leap years) in the Gregorian calendar. ... is the 29th day of the year in the Gregorian calendar. ... Year 1992 (MCMXCII) was a leap year starting on Wednesday (link will display full 1992 Gregorian calendar). ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 130th day of the year (131st in leap years) in the Gregorian calendar. ... is the 129th day of the year (130th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 6th day of the year in the Gregorian calendar. ... is the 132nd day of the year (133rd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 6th day of the year in the Gregorian calendar. ... Year 1995 (MCMXCV) was a common year starting on Sunday (link will display full 1995 Gregorian calendar). ... is the 256th day of the year (257th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 200th day of the year (201st in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... is the 39th day of the year in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... is the 13th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 207th day of the year (208th in leap years) in the Gregorian calendar. ...

External links

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Linux Kernel 2.6: It's Worth More! (3704 words)
Many Linux kernel developers expect improved versions of their code to be continuously available to them, and a release using a BSD-style license would violate those developers' expectations.
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It could be argued that the Linux kernel is embedded, since it often operates in tight constraints; but in practice these constraints aren't very tight, and the kernel project can often negotiate requirements to a limited extent (e.g., providing only partial support for a particular peripheral or motherboard if key documentation is lacking).
Linux kernel - Wikipedia, the free encyclopedia (2749 words)
The Linux kernel is a Unix-like operating system kernel that was begun by Linus Torvalds in 1991 and subsequently developed with the assistance of developers worldwide.
Currently, the Linux kernel is licensed under version 2 of the GPL, and there is some controversy over how easily it could be changed to use later GPL versions such as the upcoming version 3 (and whether this is desirable) [13].
The fact that Linux is not a microkernel was the topic of a famous flame war between Linus Torvalds and Andy Tanenbaum on comp.os.minix in 1992.
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