Overview

uniOS Wiki

uniOS is a freestanding x86-64 operating system written in C++20. It boots through the in-tree Meridian UEFI bootloader, starts a preemptive multi-core kernel, and launches a native desktop userspace session with a window manager, dock, menubar, and applications.

No libc in the kernel, no exceptions, no RTTI. Memory management, PCI, ACPI, USB, networking, audio, and display code are all written from scratch.

System at a Glance

Area	Summary
Boot	Meridian UEFI loader, repo-owned `BootInfo` ABI, GOP framebuffer with EDID-driven mode selection
Kernel	Higher-half C++20 kernel, preemptive O(1)-style scheduler, SMP up to 8 cores, syscalls via `syscall` instruction
Memory	Bitmap PMM with frame refcounts, 4-level paging, HHDM direct map, bucketed kernel heap
Filesystems	VFS with page cache, read-only uniFS root with volatile RAM overlay, FAT32 for persistent `/data`
Drivers	PCI (ECAM + legacy), ACPI/APIC, ATA, AHCI, USB xHCI/HID/MSC, PS/2, e1000, RTL8139, AC97, HDA
Networking	Polling IPv4 stack: ARP, ICMP, UDP, TCP (RFC 5681-style congestion control), DHCP, DNS
Userspace	Native ELF programs, libc subset, immediate-mode GUI library, shell with scripting, desktop apps
Display	Firmware framebuffer backend, double buffering, dirty regions, KMS-style present/compose syscalls

Reading Guide

Getting started

Building and running — toolchain requirements, build targets, QEMU run targets, test suites.
Boot images — what efi.img, boot.img, and uniOS.iso contain, and how they are assembled.

Kernel

Boot path — Meridian, the BootInfo ABI, and kernel startup order.
Memory management — PMM, VMM, kernel heap, TLB shootdowns.
Scheduling — runqueues, priorities, sleep/wakeup, timers.
SMP — AP bring-up, per-core state, shutdown protocol.
Processes — fork/exec/exit lifecycle and signals.
System calls — the syscall ABI and the complete call table.
VFS — vnodes, mounts, page cache, pipes, memfd.
Filesystems — uniFS, FAT32, and the /data volume.
Drivers — PCI, ACPI, APIC, and the driver binding model.
Storage drivers — ATA, AHCI, USB mass storage, partitions.
USB — xHCI host controller, enumeration, HID.
Input — PS/2 and USB input, event delivery.
Display — framebuffer, present/compose API.
Audio — AC97 and HDA playback.
Networking — stack layout, DHCP, DNS, socket API.
TCP — connection state machine, congestion control, limits.

Userspace

Userspace runtime — crt0, libc, libgui, how apps are built.
Window manager — the shared-memory registry and window protocol.
Shell — builtins, pipelines, line editing.
Shell scripting — variables, conditionals, loops, limits.
Desktop services and apps — init, menubar, dock, bundled apps.

Reference

Runtime configuration — settings files and keys.
Asset formats — .uoic, .uocu, .uof, .uowp.
Testing — ktest, smoke suites, SMP validation.

Repository Layout

Path	Contents
`src/bootloader/`	Meridian UEFI bootloader
`src/kernel/`, `src/mm/`, `src/fs/`, `src/net/`, `src/drivers/`	Kernel and subsystem code
`src/usr/`	Userspace runtime, libc subset, GUI library, shell, window manager, desktop services, apps
`include/`	Kernel, driver, boot, and UAPI headers
`rootfs/`	Authored runtime files staged into `unifs.img`
`appicons/`, `assets/`, `cursors/`	Sources for generated runtime assets
`tools/`	Image, filesystem, rootfs staging, asset conversion, and QEMU helper scripts
`toolchains/`	Meson cross-file configuration
`docs/`	Project site and this reference documentation

Quick Start

meson setup build/debug --cross-file toolchains/llvm.ini --buildtype debug
meson compile -C build/debug boot-disk iso
meson test -C build/debug --suite smoke --print-errorlogs