GNU Hurd
Developed by	Thomas Bushnell Roland McGrath Marcus Brinkmann Others
Latest release	K16 / December 30, 2007 (2007-12-30); 171 days ago
OS	GNU
Genre	Kernel
License	GNU General Public License
Website	http://www.gnu.org/software/hurd/

GNU Hurd (usually referred to as the Hurd) is a free software computer operating system kernel, released under the GNU General Public License. It consists of a set of servers (or daemons, in Unix terminology) that work on top of a microkernel; together they form the kernel of GNU. The Hurd aims to surpass Unix kernels in functionality, security, and stability, while remaining largely compatible with them. Hurd may refer to: GNU Hurd (a Unix-like kernel that sets the base for the GNU operating system. ... For other uses, see Software developer (disambiguation). ... Thomas Bushnell is a Gregorian friar, formerly living in Massachusetts and now in southern California. ... This page is a candidate for speedy deletion, because: Nonsense (test?) If you disagree with its speedy deletion, please explain why on its talk page or at Wikipedia:Speedy deletions. ... Marcus Brinkmann is one of the lead developers of Hurd/L4. ... Code complete redirects here. ... is the 364th day of the year (365th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... An operating system (OS) is a software that manages computer resources and provides programmers with an interface used to access those resources. ... GNU (pronounced ) is a computer operating system composed entirely of free software. ... 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 more web servers, usually accessible via the Internet. ... 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 minimal restrictions only to ensure that further recipients can also do these things. ... A kernel connects the application software to the hardware of a computer. ... GPL redirects here. ... In information technology, a server is an application or device that performs services for connected clients as part of a client-server architecture. ... In Unix and other computer multitasking operating systems, a daemon is a computer program that runs in the background, rather than under the direct control of a user; they are usually instantiated as processes. ... 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. ... 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. ... A kernel connects the application software to the hardware of a computer. ... GNU (pronounced ) is a computer operating system composed entirely of free software. ... 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. ...

HURD is a mutually recursive acronym, standing for HIRD of Unix-Replacing Daemons, where HIRD stands for HURD of Interfaces Representing Depth. It is also a play on the words herd of gnus, reflecting how it works.^[1] Mutual recursion is a form of recursion where two mathematical or computational functions are defined in terms of each other. ... A recursive acronym (or occasionally recursive initialism) is an abbreviation which refers to itself in the expression for which it stands. ... A herd of Wildebeest A gaggle of Canada geese For other uses, see Herd (disambiguation). ... Species Connochaetes gnou Connochaetes taurinus The wildebeest (plural, wildebeest or wildebeests), also called the gnu (pronounced or ), is an antelope of the genus Connochaetes. ...

Development history

Development on the GNU operating system began in 1984 and initially made good progress. Free GNU tools started to acquire a good reputation and were often adopted in preference to inferior proprietary tools provided by system vendors. By the early 1990s, the only major component missing was the kernel.^[2]

Development on the Hurd began in 1990 after an abandoned kernel attempt in 1986, based on the research TRIX operating system developed by Professor Steve Ward and his group at MIT's Laboratory for Computer Science (LCS).^[3] According to Thomas Bushnell, the initial Hurd architect, their early plan was to adapt the 4.4BSD-Lite kernel and, in hindsight, "It is now perfectly obvious to me that this would have succeeded splendidly and the world would be a very different place today".^[4] However, in 1987, due to a lack of cooperation from the Berkeley programmers, Richard Stallman proposed instead to use the Mach microkernel developed at Carnegie-Mellon University. Work on this was delayed for three years due to uncertainty over whether CMU would release the Mach code under a suitable license.^[3] This article is about the year. ... // TRIX is a research network-oriented operating system compatible with UNIX version 7. ... “MIT” redirects here. ... Project MAC, later the MIT Laboratory for Computer Science (LCS), was a research laboratory at MIT. Project MAC would become famous for groundbreaking research in operating systems, artificial intelligence, and the theory of computation. ... Thomas Bushnell is a Gregorian friar, formerly living in Massachusetts and now in southern California. ... BSD redirects here; for other uses see BSD (disambiguation). ... Sather Tower (the Campanile) looking out over the San Francisco Bay and Mount Tamalpais. ... Richard Matthew Stallman (born March 16, 1953), often abbreviated rms,[2] is an American software freedom activist, hacker,[3] and software developer. ... Mach is an operating system microkernel developed at Carnegie Mellon University to support operating system research, primarily distributed and parallel computation. ... Carnegie Mellon University is a private research university located in Pittsburgh, Pennsylvania. ...

With the release of the Linux kernel in 1991, the primary consumer of GNU's userland components soon became the Linux operating system, prompting the coining of the controversial term GNU/Linux. The Linux kernel is a Unix-like operating system kernel. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... This article is about operating systems that use the Linux kernel. ... The GNU/Linux naming controversy is a dispute among members of the free and open source software community about how to refer to the computer operating systems commonly called Linux. GNU/Linux is the term promoted by the Free Software Foundation (FSF), its founder Richard Stallman, and its supporters, for...

Development of the Hurd has proceeded slowly. Despite an optimistic announcement by Stallman in 2002^[5] predicting a release of GNU/Hurd later that year, the Hurd is still not considered suitable for production environments. Development in general has not met expectations, and there are still bugs and missing features.^[6] This has resulted in a poorer product than many (including Stallman) had expected.^[7] Also see: 2002 (number). ...

The Debian project, among others, have worked on the Hurd project to produce binary distributions of Hurd-based GNU operating systems for PC compatible systems.^[8] Debian is a free operating system. ... One of the first PCs from IBM - the IBM PC model 5150. ...

Architecture

Unlike the majority of Unix-like kernels, the Hurd builds on top of a microkernel which is responsible for providing the most basic kernel services — coordinating access to the hardware: the CPU (through process management and scheduling), RAM (via memory management), and other various input/output devices (via I/O scheduling) for sound, graphics, mass storage, etc. In theory the microkernel design would allow for all device drivers to be built as servers working in user space, but today most drivers of this kind are still contained inside GNU Mach, the currently used microkernel. That is because initially user-space drivers would have suffered from performance loss, due to the overhead of the Mach interprocess communication. With the performance of today's machines, it is possible that this overhead would no longer cause a significant performance problem.^[9] 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. ... 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. ... Computer hardware is the physical part of a computer, including its digital circuitry, as distinguished from the computer software that executes within the hardware. ... CPU redirects here. ... For disk scheduling, see I/O scheduling. ... RAM redirects here. ... Memory management is the act of managing computer memory. ... Energy Input: The energy placed into a reaction. ... I/O Scheduling which should not be confused with process scheduling. ... An operating system usually segregates the available system memory into kernel space and user space. ... GNU Mach, an implementation of the Mach microkernel, is the default microkernel in the GNU Hurd kernel of the GNU operating system. ...

Choice of microkernel

From early on, the Hurd was developed to use GNU Mach as the microkernel. This was a technical decision made by Richard Stallman, and one that he later saw as a mistake.^[10] GNU Mach, an implementation of the Mach microkernel, is the default microkernel in the GNU Hurd kernel of the GNU operating system. ...

From 2004 onward, various efforts were launched to port the Hurd to more modern microkernels. The L4 microkernel was the original choice in 2004, but progress slowed to a halt. In 2005, there was a discussion of whether to change to L4.sec (a different L4 microkernel) or to Coyotos (EROS successor).^[11] Although no formal decision was made, most of the Hurd developers' time has gone into thinking about Coyotos,^[12] especially since 2006. L4 is, collectively, a family of related computer programs. ... Coyotos is a secure operating system currently being developed by researchers[1] at the Johns Hopkins Universitys Systems Research Laboratory[2]. Objectives Though it has many objectives, one of the most interesting is to become the first formally verified operating system. ... EROS (The Extremely Reliable Operating System) is an operating system developed by the University of Pennsylvania and the Johns Hopkins University. ...

Other Unix-like systems working on top of the Mach microkernel include OSF/1, Lites, and MkLinux. These are implemented as a single Unix server which, together with the microkernel, replaces the monolithic kernel of a traditional Unix system. Mac OS X and NEXTSTEP use monolithic kernels based on Mach, often incorrectly believed to be microkernels. Mach is an operating system kernel developed at Carnegie Mellon University to support operating system research, primarily distributed and parallel computation. ... Lites is a Unix-like operating system built on the Mach microkernel. ... MkLinux is an Open Source Software project, initiated by OSF Research Institute and Apple Computer, in order to port Linux to the PowerPC platform. ... It has been suggested that Monolithic system be merged into this article or section. ... Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... NEXTSTEP is the original object-oriented, multitasking operating system that NeXT Computer, Inc. ...

In the Hurd, elements of a monolithic kernel are instead handled by separate server processes. Such a "set of servers" was one of the main design goals of Mach, but Hurd appears to be the first Mach-based system to be implemented in this way. (QNX and Minix-3 are similar but based on their own microkernels.) It is not entirely clear why this happened, but it might have something to do with the high performance hit of Mach IPC.^{[citation needed]} Hurd also aims to be microkernel-independent.^{[citation needed]} Mach is an operating system kernel developed at Carnegie Mellon University to support operating system research, primarily distributed and parallel computation. ... QNX (pronounced either Q-N-X or Q-nix) is a commercial POSIX-compliant Unix-like real-time operating system, aimed primarily at the embedded systems market. ... MINIX is a free/open source, Unix-like operating system (OS) based on a microkernel architecture. ...

OSKit-Mach began as a branch of the GNU Mach 1.2 kernel, but since the release of GNU Mach 1.3 was merged as the new GNU Mach 2.x mainline.

In 2005, Hurd developer Neal Walfield finished the initial memory management framework for the L4/Hurd port, and Marcus Brinkmann ported essential parts of glibc; namely, getting the process startup code working, allowing programs to run, thus allowing the first user programs (trivial ones such as the hello world program in C) to run. Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... Neal Walfield is one of the lead developers of Hurd/L4. ... Marcus Brinkmann is one of the lead developers of Hurd/L4. ... Glibc is the GNU projects C standard library, licensed under the LGPL. The lead contributor and maintainer is Ulrich Drepper. ... A hello world program is a computer program that prints out Hello, World! on a display device. ...

In 2006, Marcus Brinkmann and associates met with Jonathan Shapiro (a primary architect of the Coyotos Operating System) to aid in and discuss the use of the Coyotos kernel for GNU/Hurd. These discussions continued into 2007, but progress is slow.^{[citation needed]} Coyotos is a secure operating system currently being developed by researchers[1] at the Johns Hopkins Universitys Systems Research Laboratory[2]. Objectives Though it has many objectives, one of the most interesting is to become the first formally verified operating system. ...

Unix extensions

This section does not cite any references or sources. (March 2007) Please help improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed.

A number of traditional Unix concepts are replaced or extended in the Hurd.

Under Unix every program running has an associated user id, which normally corresponds to the user that started the process. This id largely dictates the actions permitted to the program. No outside process can change the user id of a running program. A Hurd process, on the other hand, runs under a set of user ids, which can contain multiple ids, one, or none. A sufficiently privileged process can add and remove ids to another process. For example there is a password server that will hand out ids in return for a correct login password. Note: to create a user account for Wikipedia, go to the login page. ... In computing, a process is an instance of a computer program that is being executed. ...

Regarding the file system, a suitable program can be designated as a translator for a single file or a whole directory hierarchy. Every access to the translated file, or files below a hierarchy in the second case, is in fact handled by the program. For example a file translator may simply redirect read and write operations to another file, not unlike a Unix symbolic link. The effect of Unix mounting is achieved by setting up a filesystem translator (using the "settrans" command). Translators can also be used to provide services to the user. For example, the ftpfs translator allows a user to encapsulate remote FTP sites within a directory. Then, standard tools such as ls, cp, and rm can be used to manipulate files on the remote system. Even more powerful translators are ones such as UnionFS, which allows a user to unify multiple directories into one; thus listing the unified directory reveals the contents of all the directories (a feature that is missing in many Unixes, although available in modern BSDs). For library and office filing systems, see Library classification. ... Not to be confused with SYmbolic LinK (SYLK), a Microsoft Office file format. ... Mounting, in computer science, is the process of making a file system ready for use by the operating system, typically by reading certain index data structures from storage into memory ahead of time. ... For other uses, see LS. ls is a command specified by POSIX and the Single UNIX Specification, and is thus implemented in Unix and Unix-like operating systems. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The title given to this article is incorrect due to technical limitations. ... UnionFS is a Linux filesystem service which implements a union mount for Linux file systems. ... BSD redirects here. ...

The Hurd requires a multiboot-compliant boot loader, such as GRUB. Multiboot Specification is standard developed by Free Software Foundation which describes method of loading various kernels. ... In computing, booting is a bootstrapping process that starts operating systems when the user turns on a computer system. ... Grub or GRUB can mean: a slang term for food a beetle larva that resembles a worm a distributed commercial search engine: see Grub (search engine) a number of places in Switzerland, Austria and Germany, such as: Grub, canton of Appenzell Outer Rhodes, Switzerland Grub, Germany for the GNU project...

Architecture of the servers

According to the Debian documentation there are 24 servers (18 core servers and 6 file system servers) named as follows:^[13]

Core servers

• auth (authentication server) : Receives requests and passwords from programs and gives them an ID, which changes the privileges of the program.
• crash (crash server):
• exec (execution server): Translates an executable image (currently ELF and a.out are supported) to a runnable image in memory.
• fifo (FIFO translator):
• new-fifo (new FIFO server)
• firmlink (the firmlink translator):
• fwd (forward server)
• hostmux (host multiplexer server);
• ifsock (server for sockets interface):
• init (init server)
• magic (magic server)
• null (null server): implements /dev/null and /dev/zero
• pfinet (pfinet server)
• pflocal (pflocal server)
• proc (process server)
• symlink (symbolic link translator)
• term (terminal server)
• usermux (user multiplexer server)

Please help improve this section by expanding it. Further information might be found on the talk page or at requests for expansion.

This article is about FIFOs in computing and electronic design. ... This article is about FIFOs in computing and electronic design. ... Image File history File links This is a lossless scalable vector image. ...

Filesystem servers

The ext2fs server "ext2fs"

The ext2 filesystem translator. It receives disk blocks from the microkernel and gives files and directories to the applications.

The iso filesystem server "isofs"

The translator for the ISO 9660 filesystem. Translates blocks of a CD or DVD to files and directories for the applications.

The nfs server "nfs"

See Network File System.

The ufs server "ufs"

Translator for the BSD filesystem of the same name, UFS.

The ftp filesystem translator "ftpfs"

See File transfer protocol

"storeio"

The storage translator

The servers collectively implement the POSIX API, with each server implementing a part of the interface. For instance, the various filesystem servers each implement the filesystem calls. The storage server will work as a wrapping layer, similar to the VFS of Linux. The ext2 or second extended file system is a file system for the Linux kernel. ... ISO 9660, a standard published by the International Organization for Standardization, defines a file system for CD-ROM media. ... For network file systems in general, see network file system. ... The UNIX file system (UFS) is a file system used by many Unix and Unix-like operating systems. ... This article is about the File Transfer Protocol standardised by the IETF. For other file transfer protocols, see File transfer protocol (disambiguation). ... POSIX or Portable Operating System Interface[1] is the collective name of a family of related standards specified by the IEEE to define the application programming interface (API) for software compatible with variants of the Unix operating system. ... An application programming interface (API) is a source code interface that a computer system or program library provides in order to support requests for services to be made of it by a computer program. ... A virtual file system (VFS) or virtual filesystem switch is an abstraction layer on top of a more concrete file system. ... This article is about operating systems that use the Linux kernel. ...

GNU/Hurd-based distributions

See also List of LiveDistros#GNU-based

• Bee GNU/Hurd
• Debian GNU/Hurd
• Superunprivileged.org GNU/Hurd Live CD

This is a large list of LiveDistros. ... Debian GNU/Hurd is the Debian Projects distribution of the GNU operating system (with GNU Hurd as its kernel). ...

Error messages

A "computer bought the farm" message is an error message displayed on GNU Hurd when one of the servers that provide kernel-like functions reaches a "hopeless" situation (after which it is usually terminated).^[14] This is a rough equivalent of a kernel panic in monolithic Unix-like kernels. A euphemism is the substitution of an agreeable or less offensive expression in place of one that may offend or suggest something unpleasant to the listener;[1] or in the case of doublespeak, to make it less troublesome for the speaker. ... This page is a candidate for speedy deletion. ... Linux kernel panic under QEMU. Mac OS X kernel panic alert. ... 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. ...

Its corresponding error code in the GNU C Library is EIEIO. In computer programming, error codes are enumerated messages that correspond to faults in a specific software application. ... Glibc is the GNU projects C standard library. ... This article contains a trivia section. ...

See also

• Free Software Foundation
• Hurd User Group
• GNU
• Debian GNU/Hurd - Debian's implementation of GNU Hurd
• Minix 3

Image File history File links Free_Software_Portal_Logo. ... 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. ... A Hurd User Group (HUG) is a group of people who use the GNU Hurd and support new Hurd users. ... GNU (pronounced ) is a computer operating system composed entirely of free software. ... Debian GNU/Hurd is the Debian Projects distribution of the GNU operating system (with GNU Hurd as its kernel). ... Debian is a free operating system. ... MINIX 3 is a project with the aim to create a small, highly reliable and functional Unix-like operating system. ...

References

Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 239th day of the year (240th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 220th day of the year (221st in leap years) in the Gregorian calendar. ... Also see: 2002 (number). ... is the 70th day of the year (71st in leap years) in the Gregorian calendar. ... PC World is a global computer magazine published monthly by IDG. It offers advice on various aspects of PCs and related items, the Internet, and other personal-technology products and services. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 220th day of the year (221st in leap years) in the Gregorian calendar. ... Location of Zagreb within Croatia Coordinates: , Country RC diocese 1094 Free royal city 1242 Unified 1850 Government  - Mayor Milan Bandić Area [1]  - Total 641. ...

External links

Wikinews has related news:

GNU Hurd operating system: first user program run using L4 microkernel

• The GNU Hurd
• The GNU Hurd - Lessons and Perspective at Google Video by Brinkmann Marcus
• The GNUFans Wiki - unofficial but current documentation of the Hurd
• Towards a New Strategy of OS Design
• Debian GNU/Hurd installation CDs
• Interview with Neal Walfield, Hurd and Hurd/L4 developer. (2001)
• Interview with Marcus Brinkmann, Hurd and Hurd/L4 developer. (2005)
• A GNU/Hurd on Mach LiveCD, based on Debian GNU/Hurd (mirror here)
• http://hurd.gnufans.org/bin/view/Hurd/NextHurd
• http://www.gnu.org/software/hurd/hurd-l4.html
• #hurd IRC channel
• Hurd contributor wiki

v • d • e GNU Project History GNU Manifesto · Free Software Foundation · History of free software Licences GNU General Public License · GNU Lesser General Public License · Affero General Public License · GNU Free Documentation License · GPL linking exception Software GNU (variants) · Hurd · GNOME · Gnuzilla · IceCat · Gnash · Bash · GCC · GNU Emacs · glibc · Coreutils · Build system · Other GNU packages and programs Public speakers Robert J. Chassell · Loïc Dachary · Ricardo Galli · Georg C. F. Greve · Federico Heinz · Benjamin Mako Hill · Bradley M. Kuhn · Eben Moglen · Richard Stallman · John Sullivan · Leonard H. Tower Jr. Other topics GNU/Linux naming controversy · Revolution OS