Show HN: Anos — a hand-written ~100KiB microkernel for x86-64 and RISC-V

What is Anos?

Anos bills itself as "An Operating System" but the repo is candid: this is more toy kernel than polished distro. It has been reported that the project is a hand‑written microkernel (roughly 100 KiB) supporting x86_64 and RISC‑V, and that it now reaches “toy kernel” status with user‑mode preemptive multitasking and multi‑CPU support. Why start from scratch? Because sometimes you want control, experiments, and clean ideas — not another layer of legacy baggage.

Key features and design

At its heart is STAGE3, a deliberately small microkernel providing scheduling, memory management and synchronous, zero‑copy IPC; user‑mode SYSTEM acts as a supervisor and supplies higher‑level services. The repo emphasizes a capability‑based security model, user‑space drivers and discovery (ACPI/Devicetree work in progress), a tiny syscall surface with fast and slow channels, and a custom toolchain based on binutils, GCC 16 (experimental) and Newlib. The author even quips "just a hobby, won't be big and professional like GNU‑Linux®" — a wink to the long lineage of hobby OS projects.

Current state and how to look

Development is active but unfinished: many features are implemented for some value of "implemented," and others remain WIP — USB xHCI, broader driver coverage and legacy support among them. It has been reported that Anos can run on real hardware and allegedly supports up to 16 CPUs; minimum supported x86_64 target is Haswell and the project is GPLv2‑licensed. Curious? Source, docs and screenshots are on the project page — feel free to poke, read the design notes, or send a patch. Not ready to dethrone your distro, but definitely worth a look if you like tiny kernels and bold experiments.

Sources: github.com/roscopeco, Hacker News