LevitateOS Kernel

The AI-Written Kernel — Part of the LevitateOS experiment.

This kernel is written entirely by AI agents. It implements the Linux syscall ABI to run unmodified musl-linked binaries. The goal is capability, not code beauty.

Quick Facts

Language	Rust (no_std)
Architectures	x86_64, AArch64
Platforms	QEMU only (real hardware aspirational)
Syscalls	70+ implemented
libc	musl (static)
Shell	BusyBox ash

Getting Started

This repository is a git submodule of the main LevitateOS project:

# Clone the full project
git clone --recursive https://github.com/LevitateOS/LevitateOS.git
cd LevitateOS

# Build and run
./run.sh              # GUI mode
./run-term.sh         # Terminal mode (Ctrl+A X to exit)
./run-vnc.sh          # Browser at localhost:6080

# Or use xtask directly
cargo xtask build kernel --arch x86_64
cargo xtask run

What Works

• BusyBox ash shell — interactive prompt, pipes, command substitution
• 80+ coreutils — ls, cat, grep, sed, sort, etc.
• fork/exec/wait — full process lifecycle
• VFS — tmpfs, devtmpfs, initramfs, FAT32, ext4 (read-only)
• Signals — basic sigaction/sigprocmask

Directory Structure

arch/               # Architecture-specific crates
├── aarch64/        # ARM64 boot, exceptions, MMU
└── x86_64/         # x86_64 boot, exceptions, MMU

levitate/           # Main kernel binary
syscall/            # Linux syscall implementations (70+)
sched/              # Scheduler and task management  
mm/                 # Memory management (buddy, VMA)
vfs/                # Virtual filesystem layer
fs/                 # Filesystem implementations
├── tmpfs/
├── devtmpfs/
├── initramfs/
├── ext4/
└── fat/
drivers/            # Device drivers
├── virtio-blk/
├── virtio-gpu/
├── virtio-input/
└── virtio-net/

Key Subsystems

Subsystem	Status	Notes
Memory	✅ Working	Buddy allocator, VMA tracking, mmap/brk
Syscalls	✅ Working	70+ Linux-compatible syscalls
VFS	✅ Working	Linux-style superblock/inode/dentry
Scheduler	✅ Working	Preemptive round-robin
Signals	🟡 Partial	sigaction works, delivery is basic
Networking	❌ Not yet	Driver exists, no TCP/IP stack

Feature Flags

Flag	Purpose
verbose	Boot logging for debugging
verbose-syscalls	Log every syscall invocation
diskless	Skip initrd requirement

Boot Sequence

1. Assembly Entry — MMU setup, stack init
2. Rust Entry (kernel_main) —
   • Exception handlers, heap, console
   • Interrupt controller (GIC/APIC)
   • Physical memory from DTB/ACPI
   • VirtIO device scan
   • Mount filesystems, parse initramfs
3. PID 1 — Spawn BusyBox init

Related

• Main Project: github.com/LevitateOS/LevitateOS
• AI Team Logs: See .teams/ in main repo (469+ sessions)
• Known Issues: See docs/GOTCHAS.md in main repo

License

MIT — See main repository.