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

by noone_youknow on 4/4/2026, 6:58:03 AM

I pretty much always have a kernel project going on, and have been that way for decades. Over the past couple of years, that&#x27;s been Anos, which has gotten further along than any of my previous hobby kernels, supporting IPC, multitasking, SMP (x86-64 only right now) and running on real hardware.<p>LLMs (mostly Claude Code) have been used during development, but I learned early on that it&#x27;s not _great_ at code at this level, so I&#x27;ve restricted its use to mostly documentation and tests. There&#x27;s _a little_ AI code in the user space, but I have a strict &quot;no AI code&quot; rule in the kernel itself. I find this helps not only with the quality &#x2F; functionality of the code, but also with learning - for example, even though I&#x27;ve written multiple kernels in the past, it wasn&#x27;t until Anos that I _truly_ grokked pagetable management and what was possible with a good VMM interface, and if I&#x27;d outsourced that implementation to an LLM I probably wouldn&#x27;t have learned any of that.<p>In terms of approach, Anos avoids legacy platform features and outdated wiki &#x2F; tutorial resources, and instead tries to implement as much as possible from manuals and datasheets, and it&#x27;s definitely worked out well so far. There&#x27;s no support for legacy platform features or peripherals, with all IO being memory mapped and MSI&#x2F;MSI-X interrupts (no PIC), for example, which has helped keep the codebase focused and easy to work on. The kernel compiles to about 100KiB on x86-64, with enough features to be able to support multitasking and device drivers in user space.<p>As a hobby project, progress ebbs and flows with pressures of my day job etc, and the main branch has been quiet for the last few months. I have however been working on a USB stack as time allows, and hopefully will soon have at least basic HID support to allow me to take the next step and make Anos interactive.<p>I don&#x27;t know how useful projects like Anos are any more, given we now live in the age of AI coding, but it&#x27;s a fun learning experience and helps keep me technically grounded, and I&#x27;ll carry on with it for as long as those things remain true.

https://github.com/roscopeco/anos

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