4RING_OS is an experimental x86 kernel project that began in 2021 and continued development for some time. It explores hardware-supported privilege separation across all four x86 rings (Ring 0–3) using real GDT segmentation and basic paging.
This code represents a research-oriented attempt to rethink kernel architecture through strict physical and logical separation — not meant for production or modern platforms.
- Original codebase from 2021 (see commit history for timeline)
- Written entirely in C and assembly
- GRUB1 + Multiboot1 compliant
- Bootable from floppy; tested on real x86 hardware
- ❗ Inactive: This project is no longer maintained and does not compile with recent versions of Clang due to deprecated syntax and incompatibility with certain inline constructs
A fork of this repository exists at github.com/mazino3/4RING_OS, made while the original was temporarily unpublished. This repository contains the original source and development history.
(C) 2021 Isa (isa@isoux.org)