Keyboard shortcuts

Press ← or → to navigate between chapters

Press S or / to search in the book

Press ? to show this help

Press Esc to hide this help

Operating Systems Reference Library

This page is a verified index of primary sources for operating systems: official documentation, developer and API portals, source repositories, SDKs, downloadable or offline documentation, a two-track learning path, and free-access research literature.

It is a navigation layer, not a tutorial. Where the rest of this book explains a concept, this page tells you which document to open to get the authoritative answer, and in what order to read things. Every link was HTTP-verified on the date shown below; sources that block automated checkers but work in a browser are flagged rather than silently dropped.

Production kernels, teaching kernels, RTOSes, the POSIX and OCI interfaces, observability tooling, and a two-track path from OSTEP to reading production kernel source.

68 entries across 8 categories, plus 58 education & reference-implementation resources (24 basic / 34 advanced), plus 10 video resources and 7 conference sources.

Every link HTTP-verified on 2026-10-07.

The OSDev Wiki returns 403 to automated clients but loads normally in a browser.

Contents

1. Production kernels & their documentation

Linux

  • Docs: docs.kernel.org
  • Developer / API: kernel.org/doc/html/latest
  • Source: github.com/torvalds/linux
  • SDKs & repos: The entire kernel is the SDK. Subsystem docs under Documentation/; elixir.bootlin.com for fast cross-referenced browsing
  • Downloadable / offline: Kernel docs build to HTML/PDF from source (make htmldocs); full tree cloneable
  • Note: Read docs.kernel.org/process/howto.html before anything else if you intend to contribute.

FreeBSD

OpenBSD

  • Docs: man.openbsd.org
  • Source: github.com/openbsd/src
  • SDKs & repos: pledge/unveil, OpenSSH, LibreSSL, pf all originate here
  • Downloadable / offline: man pages are the documentation, and they are complete
  • Note: Famous for correctness-first culture. The man pages are normative, not supplementary.

NetBSD

illumos

Haiku

ReactOS

Redox

  • Docs: doc.redox-os.org/book
  • Source: github.com/redox-os/redox
  • SDKs & repos: Microkernel OS written in Rust, with its own userland
  • Downloadable / offline: The Redox Book
  • Note: Shows what a memory-safe systems language does to OS design.

Fuchsia (Zircon)

XNU (macOS/iOS)

Windows

2. Embedded & real-time operating systems

Zephyr

FreeRTOS

Apache NuttX

seL4

3. Teaching kernels — read and modify these

xv6-riscv

  • Docs: pdos.csail.mit.edu/6.1810
  • Source: github.com/mit-pdos/xv6-riscv
  • SDKs & repos: A complete Unix-like kernel in about 10,000 lines of C
  • Downloadable / offline: The xv6 book (free PDF) — the companion text that explains every subsystem
  • Note: The single best artefact in OS education. Read the book and the source side by side.

Pintos

  • Docs: web.stanford.edu/class/…
  • SDKs & repos: Skeleton kernel with four staged projects: threads, user programs, VM, filesystem
  • Downloadable / offline: Project documentation online
  • Note: Harder than xv6 because you implement the missing parts yourself.

OS/161

  • Docs: ops-class.org
  • Source: github.com/ops-class/os161
  • SDKs & repos: Teaching OS with a full graded assignment sequence and public autograder
  • Downloadable / offline: ops-class.org hosts everything
  • Note: The most complete free OS course-in-a-box.

MINIX 3

Writing an OS in Rust

  • Docs: os.phil-opp.com
  • Source: github.com/phil-opp/blog_os
  • SDKs & repos: Incremental blog-series kernel: bootloader, interrupts, paging, async
  • Downloadable / offline: Online, with full source per post
  • Note: The best modern from-scratch tutorial, in any language.

The Little OS Book

  • Docs: littleosbook.github.io
  • SDKs & repos: Short x86 kernel-from-scratch guide
  • Downloadable / offline: Online + PDF
  • Note: Minimal and honest about scope.

OSDev Wiki

  • Docs: wiki.osdev.org/Main_Page
  • SDKs & repos: The community reference for bare-metal development: boot, A20, GDT, paging, ACPI
  • Downloadable / offline: Wiki, exportable
  • Note: Uneven in quality but irreplaceable. 403s to bots; fine in a browser.

4. Interfaces, standards & ABIs

POSIX / Single UNIX Specification

  • Docs: pubs.opengroup.org/onlinepubs/9699919799
  • SDKs & repos: The normative definition of Unix system and shell interfaces
  • Downloadable / offline: Free to read online in full
  • Note: When documentation and implementation disagree, this is the arbiter.

Linux man-pages

  • Docs: man7.org/linux/man-pages
  • SDKs & repos: Section 2 (syscalls) and 7 (overviews) are the real Linux API documentation
  • Downloadable / offline: Installable via package manager; browsable online
  • Note: The section 7 overview pages (man 7 signal, man 7 capabilities) are underused and excellent.

OCI Runtime Specification

runc

containerd

5. Observability, debugging & tracing

eBPF / bpftrace

Brendan Gregg’s site

  • Docs: brendangregg.com
  • SDKs & repos: Flame graphs, USE method, systems performance methodology
  • Downloadable / offline: Articles + free tooling
  • Note: If you measure Linux performance, this is the reference body of work.

FlameGraph

perf

strace

  • Docs: strace.io
  • Source: github.com/strace/strace
  • SDKs & repos: Syscall tracer — still the fastest way to find out what a program actually does
  • Downloadable / offline: man page

Valgrind

  • Docs: valgrind.org/docs
  • SDKs & repos: Memory error detection, cachegrind, callgrind
  • Downloadable / offline: Manual online + PDF

GDB

6. Community & currency

LWN.net

  • Docs: lwn.net
  • SDKs & repos: Kernel development reporting of exceptional technical quality
  • Downloadable / offline: Subscriber articles become free after a week
  • Note: The best single source for what is actually changing in Linux and why.

Elixir cross-referencer

  • Docs: elixir.bootlin.com/linux/latest/source
  • SDKs & repos: Browse any kernel version with symbol cross-referencing
  • Downloadable / offline: Web
  • Note: Far faster than grepping a local tree when you’re orienting.

KernelNewbies

  • Docs: kernelnewbies.org
  • SDKs & repos: Per-release changelogs and first-patch guidance
  • Downloadable / offline: Wiki

Linux From Scratch

  • Docs: linuxfromscratch.org
  • SDKs & repos: Build a working distribution from source, step by step
  • Downloadable / offline: Books as HTML/PDF
  • Note: Teaches how a userland is assembled, which kernel study alone will not.

7. Kernel learning material, labs & testing

Linux Kernel Module Programming Guide

  • Docs: sysprog21.github.io/lkmpg
  • Source: github.com/sysprog21/lkmpg
  • SDKs & repos: Actively maintained modern rewrite of the classic LKMPG
  • Downloadable / offline: Online and as PDF from the repo
  • Note: The fastest path from C programmer to writing a loadable kernel module.

Linux Inside

Linux Kernel Labs

  • Docs: linux-kernel-labs.github.io
  • Source: github.com/linux-kernel-labs/linux
  • SDKs & repos: University lab series on device drivers, memory management and filesystems with QEMU setups
  • Downloadable / offline: Sphinx docs + prepared VM images
  • Note: Structured exercises with working skeletons — rare for kernel-level teaching material.

Bootlin training materials

  • Docs: bootlin.com/docs
  • SDKs & repos: Full slide decks and lab manuals for embedded Linux, kernel and driver development
  • Downloadable / offline: Hundreds of pages of PDF slides, Creative Commons licensed
  • Note: Commercial training material given away free. Among the best embedded Linux resources in existence.

syzkaller

Rust for Linux

  • Docs: rust-for-linux.com
  • Developer / API: docs.kernel.org/rust
  • Source: github.com/Rust-for-Linux/linux
  • SDKs & repos: Rust support merged into the mainline kernel; abstractions and example drivers
  • Downloadable / offline: Project site + in-tree docs
  • Note: The most consequential change to kernel development practice in decades. Still evolving quickly.

Tock OS

  • Docs: tockos.org
  • Developer / API: book.tockos.org
  • Source: github.com/tock/tock
  • SDKs & repos: Embedded OS in Rust with memory-isolated applications on microcontrollers
  • Downloadable / offline: The Tock Book
  • Note: Shows what type-safety buys you at the embedded level, where you have no MMU to fall back on.

Hubris

Asahi Linux

  • Docs: asahilinux.org
  • Developer / API: asahilinux.org/docs
  • Source: github.com/AsahiLinux
  • SDKs & repos: Apple Silicon reverse engineering and Linux port
  • Downloadable / offline: Documentation and extensive progress reports
  • Note: Currently better documentation of Apple Silicon internals than Apple provides.

8. Research papers & open-access literature

arXiv

  • Docs: arxiv.org
  • Developer / API: info.arxiv.org/help/api/index.html
  • SDKs & repos: Preprints across all of CS; most systems, ML and PL work appears here before publication
  • Downloadable / offline: Every paper is a free PDF. Bulk access documented at info.arxiv.org/help/bulk_data/index.html; a full-text API at export.arxiv.org
  • Note: Not peer-reviewed. Treat an arXiv-only paper as a claim, not a result — but it is where you will read almost everything first.

ar5iv

  • Docs: ar5iv.labs.arxiv.org
  • SDKs & repos: Renders any arXiv paper as responsive HTML instead of PDF
  • Downloadable / offline: Free; swap arxiv.org/abs/ID for ar5iv.labs.arxiv.org/html/ID
  • Note: Makes papers readable on a phone and searchable in-page. Underused.

alphaXiv

  • Docs: alphaxiv.org
  • SDKs & repos: arXiv papers with a public comment and discussion layer
  • Downloadable / offline: Free
  • Note: Useful when a paper is contested — the discussion often contains the critique you were looking for.

Semantic Scholar

  • Docs: semanticscholar.org
  • Developer / API: api.semanticscholar.org/graph/v1
  • SDKs & repos: 200M+ papers with citation graph, influential-citation scoring and TLDR summaries
  • Downloadable / offline: Free Graph API (semanticscholar.org/product/api), bulk datasets available on request
  • Note: The best free citation graph. ‘Highly influential citations’ is a genuinely useful filter for finding what actually mattered.

OpenAlex

  • Docs: openalex.org
  • Developer / API: api.openalex.org/works
  • SDKs & repos: Fully open catalogue of works, authors, venues and institutions; successor to Microsoft Academic Graph
  • Downloadable / offline: Entirely free API with no key required; complete database snapshots downloadable
  • Note: The only large-scale bibliographic database that is open all the way down, including bulk snapshots.

DBLP

  • Docs: dblp.org
  • Developer / API: dblp.org/faq/13501473.html
  • SDKs & repos: Authoritative CS bibliography — complete author and venue listings
  • Downloadable / offline: Free; full XML dump downloadable
  • Note: The fastest way to find everything a given researcher has published, and to see a conference’s full programme by year.

OpenReview

  • Docs: openreview.net
  • Developer / API: docs.openreview.net
  • Source: github.com/openreview
  • SDKs & repos: ICLR, NeurIPS, COLM and dozens of other venues — papers plus the full review threads
  • Downloadable / offline: Free; REST API
  • Note: Reading the reviews and author rebuttals teaches you how the field evaluates work. Nothing else exposes this.

CORE

  • Docs: core.ac.uk
  • Developer / API: core.ac.uk/services/api
  • SDKs & repos: Aggregates 300M+ open-access papers from repositories worldwide
  • Downloadable / offline: Free API and bulk datasets
  • Note: Good for finding the green open-access copy when a publisher’s version is paywalled.

Unpaywall

  • Docs: unpaywall.org
  • Developer / API: api.unpaywall.org
  • SDKs & repos: Finds legal free copies of paywalled papers via DOI
  • Downloadable / offline: Free API; browser extension
  • Note: Legal, author-deposited copies only. Install the extension and most paywalls simply stop appearing.

Papers We Love

  • Docs: paperswelove.org
  • Source: github.com/papers-we-love/papers-we-love
  • SDKs & repos: A curated, categorised repository of classic CS papers with local meetup talks
  • Downloadable / offline: Repo cloneable; many PDFs mirrored in-repo
  • Note: The best starting point if you do not yet know which papers matter in a subfield.

The Morning Paper (archive)

  • Docs: blog.acolyer.org
  • SDKs & repos: Adrian Colyer’s daily paper summaries, 2014-2021
  • Downloadable / offline: Free archive, still online
  • Note: No longer updated, but the back catalogue of ~1000 summarised papers is one of the great free CS resources.

USENIX Proceedings

  • Docs: usenix.org/publications/proceedings
  • SDKs & repos: OSDI, SOSP (co-published), NSDI, ATC, FAST, Security — the core systems venues
  • Downloadable / offline: Every paper free, immediately, with no membership. Often with recorded talks
  • Note: USENIX made everything open access years before the rest of the field. If a systems paper exists, check here first.

ACM Digital Library

  • Docs: dl.acm.org
  • SDKs & repos: SIGMOD, ASPLOS, PLDI, POPL, SoCC and the ACM journals
  • Downloadable / offline: Partly open: ACM Open and author-paid OA papers are free; others are paywalled
  • Note: 403s to automated clients; loads in a browser. For paywalled items, check arXiv, the author’s homepage or Unpaywall first — the free copy usually exists.

IEEE Xplore

  • Docs: ieeexplore.ieee.org
  • SDKs & repos: ISCA, MICRO, HPCA and the IEEE journals
  • Downloadable / offline: Mostly paywalled; abstracts free
  • Note: Almost always worth searching the author’s page or arXiv instead. Architecture authors in particular post preprints widely.

DROPS / LIPIcs (Dagstuhl)

  • Docs: drops.dagstuhl.de
  • SDKs & repos: ECOOP, ITP, CONCUR, SAT and many theory venues
  • Downloadable / offline: 100% open access, free PDFs, Creative Commons licensed
  • Note: A fully open publisher. Every paper, always free, no exceptions.

arXiv cs.OS (Operating Systems)

  • Docs: arxiv.org/list/cs.OS/recent
  • SDKs & repos: Preprints in OS research
  • Downloadable / offline: Free
  • Note: Low volume — OS work mostly goes straight to OSDI/SOSP rather than arXiv.

USENIX OSDI

  • Docs: usenix.org/conference/osdi26
  • SDKs & repos: The flagship OS and systems venue
  • Downloadable / offline: Every paper free, plus talk recordings
  • Note: Alternates with SOSP. Start with the best-paper awards from the last five years.

ACM SOSP

  • Docs: sosp.org
  • SDKs & repos: The other flagship OS venue, running since 1967
  • Downloadable / offline: Recent proceedings open via ACM OA
  • Note: Historically where most of the field’s landmark papers appeared.

ACM SIGOPS

  • Docs: sigops.org
  • SDKs & repos: The OS special interest group; hosts HotOS and Operating Systems Review
  • Downloadable / offline: Much of it free
  • Note: HotOS papers are short, speculative and unusually fun to read.

EuroSys

  • Docs: eurosys.org
  • SDKs & repos: The leading European systems conference
  • Downloadable / offline: Proceedings via ACM OA
  • Note: Often more practical and implementation-focused than OSDI.

USENIX ATC

  • Docs: usenix.org/conference/atc25
  • SDKs & repos: Annual Technical Conference — applied systems work
  • Downloadable / offline: All papers free
  • Note: Where a lot of real production-systems engineering gets published.

Education & reference implementations

Two tracks: Basic builds the foundations, Advanced is about reading and extending real implementations. Everything listed is free and publicly accessible.

Basic

24 resources across 6 topics.

The one book to start with

  • Operating Systems: Three Easy Pieces (OSTEP) — Free, complete, and better written than the paid alternatives. Virtualization, concurrency, persistence. Start here and finish it.
  • xv6 book (PDF) — Short companion text explaining a real kernel line by line. Read with the source open.
  • FreeBSD Handbook — Even if you use Linux. It is the clearest systems documentation anywhere.

Courses with full public materials

Read a real kernel

The interfaces you must know

Tools to learn alongside

  • strace — Find out what a program actually asks the kernel for.
  • GDB — Learn it properly, including with QEMU for kernel work.
  • QEMU — Your kernel development machine. Boot, break, repeat, with no hardware at risk.
  • Linux From Scratch — Assemble a userland by hand once; you will never be confused about a distribution again.

Finding and reading papers

  • Papers We Love — Start here when you do not yet know which papers matter. Curated by subfield, with recorded talks.
  • The Morning Paper archive — Around a thousand papers summarised in plain language. No longer updated; still one of the best free CS resources.
  • Semantic Scholar — Free citation graph. The ‘highly influential citations’ filter is the fastest way to find what a paper actually changed.
  • Unpaywall — Install the extension. Most paywalls stop appearing, legally, because the author deposited a copy.
  • ar5iv — Read any arXiv paper as HTML instead of a two-column PDF. Swap arxiv.org/abs for ar5iv.labs.arxiv.org/html.

Advanced

34 resources across 6 topics.

Production kernel source — where to start reading

  • Linux kernel tree — Do not start at the top. Pick one subsystem and follow a single syscall through it.
  • Elixir cross-referencer — Essential for navigating. Jump by symbol, not by grep.
  • Kernel documentation — Subsystem maintainers write these; they are far better than the reputation suggests.
  • FreeBSD source — One unified tree. Significantly easier to study end to end than Linux.
  • OpenBSD source — Smaller and more consistent. Read it when Linux feels impenetrable.
  • illumos — For DTrace and ZFS specifically.
  • Contribution howto — Read before your first patch, not after it bounces.

Microkernels, verification & alternative designs

  • seL4 — The formally verified microkernel. Read the manual first.
  • seL4 reference manual (PDF) — Capability-based design stated precisely.
  • Fuchsia / Zircon — A serious modern capability-based system with real documentation.
  • Redox — Microkernel in Rust, including the userland.
  • MINIX 3 — The historically important microkernel argument, in code.
  • Haiku — A complete non-Unix design. Useful for breaking Unix-shaped assumptions.

Containers, isolation & virtualization

  • OCI Runtime Spec — Short and demystifying. Read before any container tooling.
  • runc — Where namespaces and cgroups are actually configured.
  • containerd — The layer above runc.
  • QEMU — TCG translation and the KVM interface — read accel/.
  • gVisor — A userspace kernel intercepting syscalls. An unusual and instructive point in the design space.

Observability & performance at depth

  • eBPF.io — Programmable kernel instrumentation, now the centre of Linux observability.
  • Kernel BPF docs — The verifier’s rules, and how to live with them.
  • bpftrace — Ask the kernel arbitrary questions in one line.
  • BCC — Dozens of production tracing tools; read them as examples.
  • Brendan Gregg — Methodology, not just tools. The USE method is the useful part.
  • FlameGraph — Visualize where time actually goes.
  • perf — Hardware counters, correctly interpreted.

Embedded & real-time

  • Zephyr — Device-tree-driven RTOS with serious scale and governance.
  • FreeRTOS kernel — Small enough to read the scheduler in an afternoon.
  • NuttX — POSIX semantics on microcontrollers.
  • seL4 — Where real-time guarantees meet formal verification.

Staying current

  • LWN.net — The best technical reporting on kernel development. Weekly.
  • KernelNewbies — Per-release summaries of what changed.
  • USENIX OSDI — The main OS research venue; papers are free.
  • ACM SOSP — The other one. Alternates years with OSDI.
  • ASPLOS — Where OS research meets architecture and compilers.

Video courses, channels & talks

10 resources across 2 groups. Every channel and playlist below was fetched and title-verified on 2026-10-09. Handles drift and several plausible-looking handles resolve to the wrong channel, so a 200 response is not proof of identity — the links here were each checked against the channel title.

Channels & conference recordings

  • Kernel Recipes — Annual Paris kernel conference: maintainer-level talks on schedulers, filesystems and mm.
  • linux.conf.au — linux.conf.au talks: kernel, filesystems and low-level systems depth.
  • The Linux Foundation — The Linux Foundation channel: kernel and LF event recordings.
  • USENIX — Conference recordings for most USENIX papers — free video, the fastest route into a systems paper.
  • Computerphile — Short, well-made explainers; the right first stop before a spec.
  • Neso Academy — Unit-by-unit university course playlists (OS, compiler design); verify against OSTEP and the dragon book.
  • Tsoding Daily — Livestreamed low-level building: compilers, interpreters, OS-ish projects in C and Zig.
  • Linux Plumbers Conference — The kernel working conference: scheduler, filesystem and mm tracks, recordings published by the organisers.
  • IIT Bombay — NPTEL-style operating-systems and systems-programming lecture series.

Lectures & playlists

Note: Kernel conference footage is where the real design arguments happen; the course channels below are for structure, not for currency.

Conference videos, notes & archives

7 resources across 2 groups. Conference recordings are the primary-source tier of video: the speaker is usually an author of the paper, and where a talk exists the proceedings entry is often open at the same link. Every URL here returned 200 on 2026-10-09 unless the note says otherwise.

Kernel conferences publish everything, and most of it is free; this is the one topic where the conference footage is the primary literature.

Conference channels & video archives

  • Linux Plumbers Conference — The kernel working conference: slides and recordings for every microconference.
  • linux.conf.au — Site for the conference whose recordings sit on the channel above; kernel, filesystems and embedded tracks.
  • USENIX ATC ’26 — The larger, more applied sibling of OSDI; also open.
  • FOSDEM video archive — Kernel, microkernel and embedded devrooms.
  • media.ccc.de — Kernel and low-level tracks from the Chaos congresses.
  • DebConf Videos — Debian conference recordings: packaging, boot, init and distro-infrastructure talks.

Notes, proceedings & paper-adjacent archives

  • USENIX ;login: — Practitioner articles on the same material, easier to skim than a talk.

If you only do three things

  1. Read OSTEP cover to cover. It is free, complete, and better than the textbooks people pay for.
  2. Read all of xv6 with the xv6 book open beside it. Ten thousand lines, one complete Unix.
  3. Do MIT 6.1810’s labs. Public, autograded, and they force the knowledge in.

Honest notes

  • Do not start by reading Linux. It is 40 million lines. Read xv6 first; Linux becomes navigable afterwards.
  • The FreeBSD Handbook is the best OS documentation written, regardless of which OS you use.
  • man 7 pages are underrated. man 7 signal, man 7 capabilities, man 7 namespaces are concise and authoritative.
  • Containers are not a kernel feature. Read the OCI runtime spec and runc and the mystery evaporates in an hour.
  • XNU source is published but undocumented. Treat it as source, not as a reference.