Linux without Linux: AI wrote a brand-new kernel in 11 days

Gregory Kurtzer, a co-founder of CentOS and the founder of Rocky Linux, has unveiled Ginux. It is a new operating system kernel written from scratch in Rust. It is not a Linux fork, but it speaks the Linux binary interface (the Linux ABI), so ordinary Linux programs run on it unmodified.

The interesting part is who wrote it. The prototype took 11 days, and almost all of the code came from an OpenAI Codex agent running GPT-5.6 Sol in one long, persistent task. The snapshot from October 23 has 138,790 lines of code and tests and 1,037 commits. Kurtzer puts the API bill at roughly $8,000, though he did not keep exact token counts.

Kurtzer barely touched the code himself. He says he even closed his editor so he would not be tempted to fix things by hand. He set the architecture, milestones and acceptance criteria, and the agent wrote the code, built the kernel, booted it in the QEMU emulator, read the logs and fixed its own bugs. It was not hands off: at one point the agent spun its wheels for two days on a task that was too broad until he narrowed it. He calls the approach Human-Directed Agentic Engineering.

Why Codex and not Claude? Kurtzer says that in earlier projects Claude models were more likely to wander into interesting side quests and burn tokens on them. He admits he ran no controlled comparison.

What it can do today: run selected Alpine Linux programs and boot a Rocky Linux 10 userspace with systemd all the way to multi-user.target. Of 375 Linux system calls, 82 are fully implemented and 245 partially. In early sysbench runs Ginux managed 48 MiB/s on the memory test against 679 for Linux; after fixes that Codex itself tracked down it reached 620. Those numbers come from emulation on a single virtual CPU, so they are not a real kernel versus kernel comparison.

The code is on GitHub under the Apache 2.0 license. Kurtzer is upfront that Ginux is a research prototype: few drivers, no security audit, nowhere near replacing Linux.

A kernel in 11 days sounds like marketing, but the real point is different. A seasoned engineer no longer writes the code; he sets the tasks for an agent and signs off on the work.