A Modern 64-Bit Operating System Built from Scratch
Welcome to the LikeOS home page. LikeOS is a modern 64-bit operating system built entirely from scratch, demonstrating contemporary OS development with a complete Unix-like userland.
LikeOS was written by Nikolaos Rangos.
LikeOS 0.2.5-HEAD
Version 0.2.5 has these key features:
- 64-bit long mode kernel with higher-half mapping.
- UEFI boot path with framebuffer and memory map handoff.
- Interrupt and exception handling with IDT and PIC/APIC integration.
- SMP support for up to 64 CPUs with AP startup using INIT-SIPI-SIPI.
- Per-CPU data structures, run queues, and scheduler accounting.
- LAPIC timer setup, IOAPIC routing, TLB shootdown, and SMP-aware locking.
- Preemptive multitasking scheduler with fork, execve, exit, wait4, signals, and pipes.
- User mode execution in ring 3 with ELF64 binary loading and #! scripts.
- ext4 as the root filesystem — read and write, with extents, hash-indexed directories, extended attributes and a journal — plus FAT32, VFS and devfs layers.
- Demand paging: anonymous memory, brk, BSS and private file mappings are populated on first touch rather than at exec, alongside copy-on-write fork.
- Dentry cache, inode cache, and page cache with read-ahead and CLOCK-style eviction.
- Multi-user login: init, getty and login with PAM and yescrypt, users and groups, and file permissions enforced in the VFS.
- POSIX threads, System V and POSIX shared memory, poll/select/epoll, and PTYs, with per-task x87/SSE state carried across context switches.
- UTF-8 throughout: the console decodes it and addresses glyphs by code point, and the C library implements the full multibyte and wide-character interface.
- xHCI USB 3.0 stack and USB mass storage driver.
- PS/2, I2C-HID, PCI, APIC, and ACPI hardware support; VMware SVGA II graphics with a hardware cursor.
- TCP/IP networking stack with BSD-style sockets and multiple NIC drivers.
- Physical and virtual memory management with SLAB allocator, stack canaries, and security protections.
- Virtual terminals (VTs) with POSIX-like TTY, xterm-compatible escape handling, and signal handling.
- Userland libc with dynamic runtime linker, dlopen, POSIX regular expressions and iconv.
- Framebuffer console with scrollback, a scrollbar and a mouse pointer.
- Core utilities: ls, cat, cp, mv, rm, grep, sed, find, top, ps, and many more.
- Ported applications: bash 5.2 as the system shell, OpenSSH 10.4 (client and server), OpenSSL, curl, tmux, nano, and netcat.
- An X.Org desktop: the X server on the framebuffer with the ctwm window manager, xterm, the NetSurf web browser, the XNEdit editor, xcalc, xclock and xload.
- GTK3: GTK 3.24 and the stack under it — GLib, Cairo, Pango, HarfBuzz, gdk-pixbuf and libepoxy — with the Adwaita icon theme, the DejaVu fonts and the shared MIME database.
- GTK3 applications: PCManFM, which draws the desktop and manages files, the Claws Mail client speaking IMAP, POP3 and SMTP over TLS, and the Mousepad text editor.
- Runs on VMware, VirtualBox and QEMU, and on real hardware — though the only machines it has been tested successfully on so far are the Lenovo ThinkPad P50 and Dell Pro 16 Plus notebooks.
LikeOS 0.2.4-HEAD running X.Org, ctwm, xterm, XNEdit, bash and nano
— click for full size
LikeOS 0.2.4-HEAD running the NetSurf browser and logged in to a
remote Ubuntu system over SSH — click for full size
LikeOS 0.2.5-HEAD has GTK3 ported — here the PCManFM desktop
and file manager, and the Mousepad editor — click for full size
LikeOS 0.2.5-HEAD running Claws Mail as an ordinary user, sending
mail and connected to the author's IMAP inbox — click for full size
LikeOS 0.2.5-HEAD running the HexChat IRC client joined into a channel,
xfce4-terminal and galculator, with the new taskbar at the bottom — click for full size
Shown at 1920×1200, which is what a default build asks the firmware for.
Trying it. At the login prompt, log in as root with the password toor, create an ordinary account with adduser, and type startx to bring up the desktop. PCManFM draws the wallpaper, the icons and the launchers in ~/Desktop, so all three mouse buttons over the background belong to it; the window manager's menus are on Alt+F1 (Xterm, Explorer, Editor, Xnedit, Mail, Browser, Calculator, and “Exit session” to return to the console) and Alt+F2. Any user can run startx: the X server is installed setuid root and gives root up as soon as it has opened the framebuffer and the input devices, so no group membership is needed.
Building. Ubuntu is currently required as the build host — building has been tested with Ubuntu 24.04.3 LTS (Noble Numbat). Install the dependencies with sudo apt-get update and sudo make deps, then write a USB stick with make usb-write USB_DEVICE=/dev/sdb and boot it, on real hardware or by pointing VMware or VirtualBox at the USB device. The QEMU targets, make qemu and make qemu-usb, are legacy.
A default build asks for a 1920×1200 screen and falls back through the usual modes if the display cannot do it. make SCREEN_SIZE=medium prefers 1280×800 instead, and make MAX_SCREEN_SIZE=1920x1080 puts a ceiling on the list. The ceiling is what a virtual machine on a 1920×1080 notebook needs: it advertises 1920×1200 whatever the host's panel can actually show, and a build with no ceiling takes it.
Canonical URL: https://likeos.systemtrap.com
LikeOS is a Unix-like operating system designed to demonstrate modern OS development from the ground up. It features a complete userland with process management, syscalls, preemptive multitasking, symmetric multi-processing (SMP), a multi-user login, and bash as the interactive shell. The system boots via UEFI from an ext4 root filesystem, runs on (some) real hardware as well as virtual machines (QEMU, VMware, VirtualBox), and includes a rich set of core utilities, a C library with dynamic linking support, TCP/IP networking with OpenSSH, and an X.Org desktop running GTK3 applications.
The author, Nikolaos Rangos, can be reached at niko@systemtrap.com.
The git repository is available at: https://github.com/kctherootkey/LikeOS-64
LikeOS is released under the GNU General Public License version 2. See the COPYING file in the repository for the full license text.
The current development version is available on GitHub:
https://github.com/kctherootkey/LikeOS-64