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name: os-source-search description: Search reference OS source code online (Linux, xv6, seL4, MINIX3, Fuchsia/Zircon, FreeBSD). Use when looking up implementation patterns, understanding how production or teaching OSes handle specific features, or finding reference code for scheduler, memory management, IPC, drivers, syscalls. allowed-tools: WebFetch, WebSearch

OS Source Search Skill

Search reference operating system source code using online code browsers and repositories. Covers both monolithic kernels and microkernels (including userspace servers).

When to Use

• Implementation reference: See how production kernels implement features
• Learning: Understand OS concepts through real code examples
• API patterns: Find syscall implementations, driver interfaces
• Algorithm details: Scheduler policies, memory allocators, lock implementations
• Code structure: How kernels organize subsystems, headers, Makefiles

Online Resources

Linux Kernel:

• Bootlin Elixir: https://elixir.bootlin.com/linux/latest/source — Best for browsing and cross-references
• GitHub mirror: https://github.com/torvalds/linux

xv6 (MIT teaching OS):

• xv6-riscv: https://github.com/mit-pdos/xv6-riscv — RISC-V version

seL4 (verified microkernel):

• GitHub: https://github.com/seL4/seL4

MINIX3:

• GitHub: https://github.com/Stichting-MINIX-Research-Foundation/minix

Fuchsia/Zircon (Google microkernel):

• Fuchsia source: https://fuchsia.googlesource.com/fuchsia
• Zircon kernel: https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/zircon/kernel/
• Docs: https://fuchsia.dev/fuchsia-src/concepts/kernel

FreeBSD:

• CGit: https://cgit.freebsd.org/src/tree/sys — Official source browser
• GitHub mirror: https://github.com/freebsd/freebsd-src

Search Patterns

Using WebFetch for specific files

Copy# Linux
WebFetch: https://raw.githubusercontent.com/torvalds/linux/master/kernel/sched/core.c

# xv6
WebFetch: https://raw.githubusercontent.com/mit-pdos/xv6-riscv/riscv/kernel/proc.c

# seL4
WebFetch: https://raw.githubusercontent.com/seL4/seL4/master/src/syscall.c

# MINIX3
WebFetch: https://raw.githubusercontent.com/Stichting-MINIX-Research-Foundation/minix/master/minix/kernel/proc.c

# Fuchsia/Zircon (googlesource needs ?format=TEXT)
WebFetch: https://fuchsia.googlesource.com/fuchsia/+/refs/heads/main/zircon/kernel/kernel/scheduler.cc?format=TEXT

# FreeBSD
WebFetch: https://raw.githubusercontent.com/freebsd/freebsd-src/main/sys/kern/sched_ule.c

Using WebSearch for discovery

Copy# Linux
WebSearch: "linux kernel site:elixir.bootlin.com <feature>"

# xv6
WebSearch: "xv6 site:github.com <feature>"

# seL4
WebSearch: "seL4 site:github.com <feature>"

# MINIX3
WebSearch: "minix site:github.com <feature>"

# Fuchsia/Zircon
WebSearch: "zircon site:fuchsia.googlesource.com <feature>"

# FreeBSD
WebSearch: "freebsd site:cgit.freebsd.org <feature>"