# Building MontaukOS

## Build Dependencies

### Toolchain

| Dependency | Purpose |
|---|---|
| `gcc` / `g++` | C/C++ compiler (C++20, GNU11) |
| `nasm` | x86_64 assembly |
| `make` | Build system |
| `git` | Fetching dependencies (Limine, freestanding headers, cc-runtime) |
| `curl` or `wget` | Downloading `limine.h` header |

### ISO/Disk Image Creation

| Dependency | Purpose |
|---|---|
| `xorriso` | Creating bootable ISO images |
| `mtools` | Creating FAT-formatted HDD images (`mformat`, `mcopy`, `mmd`) |
| `gdisk` | GPT partitioning for HDD images (`sgdisk`) |

### Running in QEMU

| Dependency | Purpose |
|---|---|
| `qemu-system-x86-64` | x86_64 emulation |
| `ovmf` | UEFI firmware for QEMU |

For other architectures, install the corresponding QEMU system emulator (`qemu-system-aarch64`, `qemu-system-riscv64`, etc.).

## Ubuntu / Debian

Install all build dependencies with:

```bash
sudo apt install build-essential nasm git curl xorriso mtools gdisk qemu-system-x86 ovmf
```

`build-essential` provides `gcc`, `g++`, and `make`.

## Building

1. Clone the repository:
   ```bash
   git clone https://github.com/danihamm/MontaukOS.git
   cd MontaukOS
   ```

2. Build the ISO:
   ```bash
   make
   ```
   This will automatically fetch dependencies (Limine bootloader, freestanding headers, cc-runtime) and produce an ISO image.

3. Run in QEMU:
   ```bash
   make run
   ```

### Other Targets

| Target | Description |
|---|---|
| `make all-hdd` | Build a raw HDD image instead of ISO |
| `make run-hdd` | Run the HDD image in QEMU |
| `make run-bios` | Run in QEMU with legacy BIOS (x86_64 only) |
| `make clean` | Remove build artifacts |
| `make distclean` | Remove everything including downloaded dependencies |

### Cross-Architecture Builds

The kernel is split into architecture-neutral code and per-architecture
ports under `kernel/src/Arch/` (see [porting.md](porting.md)). x86_64 is the
only complete port. `aarch64` is a skeleton: the whole kernel compiles and
links for it, but paging, exception vectors, the GIC and the timer are not
written yet, so it does not boot. Userspace is x86_64-only.

Non-x86 kernels are built with LLVM (`clang`, plus `ld.lld` for the link):

```bash
make kernel ARCH=aarch64                    # kernel/bin-aarch64/kernel
make kernel ARCH=aarch64 KERNEL_LD=/path/to/ld.lld
./scripts/check-arch-neutral.sh             # boundary check + aarch64 compile
```