MakaOS

A 64-bit hobby operating system for x86-64, built from scratch — from the UEFI bootloader up through a 4-way SMP kernel, a custom libc, and a ported wlroots/Wayland desktop stack, all booted and tested in QEMU.

Features

Boot

• UEFI/OVMF boot (boot/uefi): a BOOTX64.EFI (clang COFF) collects the E820 memory map and GOP framebuffer, installs a higher-half mapping, and hands off to the kernel. A legacy second-stage C loader (kernelLoader/) with its own AHCI/PMM/VMM is kept in-tree as well.

Kernel (kernel/)

• 4-way SMP: per-CPU runqueues, an MLFQ scheduler over a Chase-Lev work-stealing deque, RCU, and lock-minimized hot paths.
• Memory: buddy-allocator PMM with per-CPU magazines, VMM with demand paging, copy-on-write fork, per-process VMAs, and a slab + kernel-heap allocator.
• Ring-3 userspace: ELF64 loader, syscall/sysret fast path, per-process kernel stacks via TSS, real TLS (%fs), futexes, and kernel-owned thread join — enough to run pthreads-heavy programs.
• ~118 syscalls with Linux-style -errno returns, including POSIX signals, pipe, dup/fcntl, epoll/eventfd/timerfd/signalfd, io_uring, and Unix-domain sockets with SCM_RIGHTS.
• Drivers: PCI, IRQ-driven AHCI, NVMe, virtio-gpu (DRM/KMS), virtio-net, virtio-input (absolute tablet), Intel HD Audio, and PS/2 keyboard + mouse.
• Networking: an ARP / IPv4 / UDP / TCP stack over virtio-net.
• Filesystems: ext2 (read and write) behind a small VFS, with pollable /dev character devices.

Userspace (userland/)

• A from-scratch libc (System V AMD64 ABI) with TLS, pthreads, and a __thread errno; bash 5.2 runs as /bin/sh.
• A POSIX conformance suite (test_posix1, 156 assertions) plus assorted apps, including a DOOM port.

Desktop (upstream ports, not custom code)

• A wlroots-0.18 stack cross-compiled and run on the kernel's virtio-gpu/DRM + libinput path: the sway compositor, foot terminal, swaybg wallpaper, tofi launcher, and wlr-randr, with an absolute virtio-tablet pointer. Actively being stabilized — see docs/.

Repository layout

boot/           UEFI bootloader (boot/uefi) + early boot assets
kernelLoader/   Legacy second-stage C loader (AHCI/ATA, early PMM/VMM)
kernel/         mm, proc/sched, syscalls, signals, VFS/ext2, net stack,
                drivers (AHCI / NVMe / virtio-gpu/-net/-input / HDA / PS-2)
userland/       libc, pthreads, and apps; bash as /bin/sh
scripts/        Cross-toolchain + upstream-port build scripts (port-*.sh)
docs/           Architecture, SMP design, lock inventory, session notes
build.sh        Build the sysroot and assemble the ext2 disk image
run.sh          Boot the image in QEMU (UEFI/OVMF, virtio-gpu + SDL display)

Engineering rules live in PRINCIPLES.md, CODE_STYLE.md, MAKAOS.md, DEBUGGING.md, and DO_NOT_TOUCH.md; CLAUDE.md indexes them.

Building and running

Prerequisites: the cross toolchain built by scripts/build-toolchain.sh, plus qemu-system-x86_64, e2fsprogs (mkfs.ext2, debugfs), OVMF, and nasm.

bash build.sh   # build + assemble build/disk.img
./run.sh        # boot it in QEMU (UEFI/OVMF, SDL window)

QEMU exposes a GDB stub on tcp::1234; the kernel ELF carries DWARF, so gdb build/kernel.elf then target remote :1234 attaches.

Status

In active development and unmistakably a learning project — but a substantial one. It boots under QEMU (TCG and KVM), runs bash and multithreaded userland, brings up a Wayland compositor, and drives real input/audio/network/storage devices. Rough edges remain: the desktop's client-presentation path and a few subsystems are still being hardened.