MINIX 3

MINIX 3 is a free, open-source operating system designed to be highly reliable, flexible, and secure. Unlike traditional monolithic kernels (like Linux or Windows) where a single driver crash can bring down the entire system, MINIX 3 is built on a tiny microkernel architecture.

The project's primary goal is to create a "self-healing" system that can detect and repair its own faults on the fly without user intervention.

Note: This repository is a fork maintained by David Montero and is NOT maintained by the Stichting MINIX Research Foundation. See What's New for changes relative to upstream.

• Fault Tolerance — Most of the OS runs as isolated user-mode processes. If a driver crashes, it is automatically restarted by the Reincarnation Server without affecting the rest of the system.
• Microkernel Design — The kernel itself is only about 6,000 lines of executable code, making it easier to verify and secure.
• POSIX Compliant — Supports a wide range of standard UNIX software.
• NetBSD Compatibility — Uses the NetBSD pkgsrc package management system, giving access to thousands of prebuilt packages.
• Multi-Architecture — Runs on x86 (IA-32), x86-64 (amd64), and ARM.
• SMP Support — Symmetric multi-processing up to 32 CPUs.
• Educational Foundation — Originally created by Andrew S. Tanenbaum; a world-class resource for learning OS design and implementation.

MINIX 3 is structured in four layers:

The headline change is a working x86-64 (amd64) kernel port that boots to a login prompt on both legacy BIOS and UEFI firmware, with SMP, an IPC fastpath, modern CPU features, and most NetBSD userland tools intact. Other highlights since the upstream base:

• amd64 SMP — full AP bring-up, per-CPU GDT/IDT/TSS, BKL serialization, validated on -smp 2/4/8 up to 32 CPUs. (See the "amd64 subsystem state" table below.)
• IPC fastpath + colocation — SENDREC same-CPU fastpath plus a Tier 1 scheduler that migrates servers to their dominant client's CPU; 4.86× SMP IPC throughput improvement on -smp 4 (p50 78k → 16k cycles).
• Hybrid BIOS + UEFI boot — single CD image boots on either firmware via El Torito with a GRUB-built EFI System Partition. Multiboot 2.0 + ACPI RSDP handoff implemented; linear-framebuffer text console for headless UEFI environments.
• Modern CPU features — NX/XD enforcement, XSAVE/AVX FPU context, eager FPU dispatch on amd64, SSE4 / AVX2 / AES-NI / RDRAND / x2APIC / PCID detection.
• New drivers — Intel I225/I226 2.5 GbE (igc), EHCI USB host (Phase 1), OHCI scaffolding (Phase 3a), multi-controller usbd, AHCI / legacy IDE auto-detect at boot.
• Allocator — switched libc to jemalloc.
• Security hardening — tree-wide audit replacing unsafe strcpy / sprintf / system() patterns; buffer-overflow fixes in kgets, backup, fdisk, minix-service; ELF auxvec UID/GID populated correctly.
• Performance — 30+ O(N²) strlen-in-loop patterns eliminated across the tree.
• Build & toolchain — GCC 15 compatibility, LLVM/clang by default, NetBSD 10 host-tools sync, C++ ATF and kyua-cli tests re-enabled.
• Test coverage — new ATF tests for dup2, libc string functions, the ISC event timer library, hgfs, cd9660, and PM ptrace.

For the full change log, see RELEASE_NOTES.md.

A snapshot of where each piece of the amd64 port stands. ✓ = production-grade, ↻ = working with caveats, ⌛ = in progress, ✗ = not implemented.

For the best experience, run MINIX 3 inside a virtual machine.

• Hypervisor: VirtualBox, VMware, or QEMU
• Image: build from source (see below) or download from the upstream Official Downloads Page

# i386 (original upstream target)
sh build.sh -j4 -mi386 -O ../obj.i386 -U release
bash releasetools/x86_cdimage.sh

# amd64 (this fork) — replace 24 with your CPU core count
sh build.sh -m amd64 -U -j24 -O ../obj.amd64 release
OBJ=../obj.amd64 bash releasetools/amd64_cdimage.sh

The build produces minix_amd64.iso in the current directory.

Important — -cpu host is required for amd64. MINIX uses the WRFSBASE instruction for TLS setup; QEMU's default kvm64 CPU model does not expose that feature (CPUID leaf 7 EBX bit 0), so the kernel will panic at boot without it.

# amd64 — bootloader path (recommended)
qemu-system-x86_64 --enable-kvm -cpu host -smp 4 -m 256 \
    -cdrom minix_amd64.iso

# amd64 — direct kernel path (faster iteration)
qemu-system-x86_64 --enable-kvm -cpu host \
    -kernel ../obj.amd64/minix/kernel/kernel \
    -append "bootcd=1 cdproberoot=1" \
    -cdrom minix_amd64.iso

# i386
qemu-system-i386 --enable-kvm -m 256 -cdrom minix_i386.iso

# amd64 HDD image
qemu-system-x86_64 --enable-kvm -cpu host -m 256 -hda minix_amd64.img

1. Create a VM (256 MB RAM, 2 GB+ HDD).
2. Mount the ISO and boot (use -cpu host for amd64 in QEMU).
3. Log in as root (no password).
4. Run setup and follow the prompts.
5. Power off, remove the ISO, reboot.

For detailed instructions see the MINIX 3 Installation Guide.

• Official Wiki: wiki.minix3.org
• User Guide: Getting Started
• Release Notes: RELEASE_NOTES.md — detailed changelog since the fork
• Book: Operating Systems: Design and Implementation (3rd ed.) — Tanenbaum & Woodhull

Pull requests are welcome. Whether you are fixing bugs, porting drivers, or improving documentation:

• Source tree is at /usr/src on a running MINIX system.
• Please follow existing BSD code style.
• Prefer strlcpy/strlcat over strcpy/strcat; snprintf over sprintf.
• For security-sensitive changes, reference the relevant CWE in the commit message.

MINIX 3 is released under the BSD-3-Clause License. See the LICENSE file for details.