Xv6

xv6
xv6 startup, and using the " ls " command
Developer	MIT
Written in	C and assembly
OS family	Unix-like
Source model	Open source
Latest release	RISC-V: rev5 / September 2, 2025;55 days ago (2025-09-02) x86-32 (EOL): rev11 / September 2, 2018;7 years ago (2018-09-02) x86-64: rev1 / September 1, 2025;56 days ago (2025-09-01)
Available in	English
Supported platforms	multiprocessor Intel x86 and RISC-V
Kernel type	Monolithic
Default user interface	Command-line interface
License	MIT license
Official website	pdos.csail.mit.edu/6.1810/xv6

xv6 is a modern reimplementation of Sixth Edition Unix in ANSI C for multiprocessor x86 and RISC-V systems. It was created for educational purposes in MIT's Operating System Engineering course in 2006. ^[1]

Purpose

MIT's Operating System Engineering course formerly used the original V6 source code. xv6 was created as a modern replacement, because PDP-11 machines are not widely available and the original operating system was written in archaic pre-ANSI C. Unlike Linux or BSD, xv6 is simple enough to cover in a semester, yet still contains the important concepts and organization of Unix. ^[1]

Self-documentation

One feature of the Makefile for xv6 is the option to produce a PDF of the entire source code listing in a readable format. The entire printout is only 99 pages, including cross references. ^[2] This is reminiscent of the original V6 source code, which was published in a similar form in Lions' Commentary on UNIX 6th Edition, with Source Code.

xv6 book

xv6 source code is paired by a commentary book that explains key concepts of operating systems using xv6 as an example. It also mentions which parts of the OS can be improved further, and how. For example, Version 5 of RISC-V xv6 ^[3] book, among others, introduces following topics:

• OS Interfaces
• OS organization
• Page tables
• Traps and system calls
• Page faults
• Interrupts and device drivers
• Locking
• Scheduling
• Sleep and Wakeup
• File system

Educational use

xv6 has been used in operating systems courses at many universities, including:

• Adolfo Ibanez University
• University of the Andes (Colombia)
• Ben-Gurion University ^[4]
• Binghamton University
• Boston College
• CentraleSupélec
• Columbia University ^[5]
• Ghulam Ishaq Khan Institute ^[6]
• Federico Santa María Technical University
• George Washington University ^[7]
• Nile University ^[8]
• Georgia Tech ^[9]
• IIIT Allahabad
• IIT Bhubaneswar and PEC Chandigarh
• IIT Bombay ^[10]
• IIT Delhi
• IIT Madras
• IIT Gandhinagar
• IIIT Delhi
• IIIT Bangalore
• IIIT Hyderabad
• Iran University of Science and Technology ^[11]
• Johns Hopkins University ^[12]
• Karlsruhe Institute of Technology ^[13]
• Linnaeus University ^[14]
• Milwaukee School of Engineering
• Motilal Nehru National Institute of Technology Allahabad
• National Taiwan University ^[15]
• National University of Córdoba ^[16]
• National University of Río Cuarto ^[17]
• New York University
• Northeastern University ^[18]
• Northwestern University ^[19]
• Portland State University ^[20]
• Rutgers University ^[21]
• RWTH Aachen University ^[22]
• Slovak University of Technology in Bratislava ^[23]
• Southern Adventist University ^[24]
• Stony Brook University ^[25]
• Technion – Israel Institute of Technology ^[26]
• Télécom SudParis ^[27]
• Tsinghua University ^[28]
• Federal University of Minas Gerais ^[29]
• University College Dublin ^[30]
• University of Belgrade School of Electrical Engineering ^[31]
• University of California, Irvine
• University of California, Riverside ^[32]
• University of Delaware ^[33]
• University of Hyderabad
• University of Illinois at Chicago ^[34]
• University of Leeds ^[35]
• University of Modena and Reggio Emilia ^[36]
• University of Otago ^[37]
• University of Palermo ^[38]
• University of Pittsburgh ^[39]
• University of Strasbourg ^[40]
• University of South Florida ^[41]
• University of Tehran ^[42]
• University of Texas at Austin ^[43]
• University of Utah ^{[44] [45]}
• University of Virginia ^[46]
• University of Wisconsin–Madison ^[47]
• University of Kassel
• Yale University ^[48]

See also

• Free and open-source software portal

• Pintos
• Not Another Completely Heuristic Operating System (Nachos)
• Minix
• Xinu

References

1. "Xv6, a simple Unix-like teaching operating system" . Retrieved 2025-05-06. Xv6 is a teaching operating system developed in the summer of 2006
2. "xv6 source listing (x86 only, not available for RISC-V)" (pdf). Retrieved 2018-01-10.
3. Cox, Russ; Kaashoek, Frans; Morris, Robert. xv6: A Simple, Unix-like Teaching Operating System. MIT Department of Electrical Engineering and Computer Science.
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9. "General Information — CS-3210, Fall 2017 1 documentation". cs3210.cc.gatech.edu. Retrieved 2019-06-21.
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19. "EECS 343: Operating System, Fall 2016–17". Archived from the original on 2018-10-24. Retrieved 2018-11-11.
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21. "01:198:416: Operating Systems Design". Archived from the original on 2012-09-11. Retrieved 2010-02-05.
22. "Advanced Operating Systems – Operating Systems Teaching and Research Unit". www.os.rwth-aachen.de. Retrieved 2025-10-13.
23. "Operačné systémy". UIM (in Slovak). Retrieved 2019-10-28.
24. "School of Computing at Southern Adventist University". Archived from the original on 2018-10-20. Retrieved 2017-12-10.
25. "CSE 306 -- Course Information" . Retrieved 2021-04-14.
26. "094210 Computer Organization and Operating System, Spring 2020" . Retrieved 2020-05-14.
27. "CSC 4508 - Operating Systems" . Retrieved 2024-06-26.
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29. "DCC605: Sistemas Operacionais" . Retrieved 2015-11-16.
30. "COMP20180 Intro to Operating Systems" . Retrieved 2023-04-04.
31. "Operativni sistemi 2 - Projektni zadatak" (in Serbian). Archived from the original on September 22, 2020. Retrieved 2021-11-20. Zadatak studenta je da izmeni deo operativnog sistem xv6 tako da podrži raspoređivače čije je opis dat u ovom projektu.
32. "CS 202: Advanced Operating System" . Retrieved 2017-12-02.
33. "CISC361: Operating Systems" . Retrieved 2025-03-31.
34. "CS385 – Operating Systems Concepts and Design". Archived from the original on 2021-09-21. Retrieved 2015-03-18.
35. "Module and Programme Catalogue". webprod3.leeds.ac.uk. Retrieved 2020-10-14.
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39. "CS 1550 Introduction to Operating Systems (COE 1550) -Fall 2020". people.cs.pitt.edu. Retrieved 2020-09-28.
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43. "Master's in Computer Science | Computer & Data Science Online". cdso.utexas.edu. Retrieved 2025-05-10.
44. "CS 6460: Operating Systems" . Retrieved 2014-01-20.
45. "Embedded in Academia : Xv6" . Retrieved 2014-04-08.
46. "CS4414: XV6 introduction" . Retrieved 2022-02-27.
47. "CS-537: Introduction to Operating Systems" . Retrieved 2011-11-04.
48. "CS422/522: Operating Systems, Spring 2010 — Overview". Archived from the original on 2012-07-23. Retrieved 2010-02-05.

External links

• 6.1810: Operating Systems Engineering

RISC-V:

• xv6 source code
• xv6 book source code
• xv6: a simple, Unix-like teaching operating system, xv6 book rev5.
• Printable version of the xv6 source code, rev5.

x86-32 (unmaintained):

• xv6 source code
• xv6 book source code
• xv6: a simple, Unix-like teaching operating system, xv6 book rev11.
• Printable version of the xv6 source code, rev11.

x86-64 (maintained by University of Strasbourg):

• xv6-64 source code
• xv6-64 book source code (EN)
• xv6-64 book source code (FR)
• xv6-64: a simple, Unix-like teaching operating system, xv6-64 EN book
• xv6-64: un système d’exploitation simple, proche d’Unix, pour l’enseignement, xv6-64 FR book