leviso

ISO builder for LevitateOS. Downloads Rocky Linux 10, extracts packages, builds EROFS rootfs, outputs bootable ISO.

Status

Alpha. Boots in QEMU. Limited bare metal testing.

Works	Doesn't work / Not tested
QEMU boot (UEFI + BIOS)	Most bare metal hardware
EROFS live root	Custom kernel (uses Rocky's)
busybox initramfs	Secure boot
Rocky package extraction	Non-x86_64 architectures

What It Does

Rocky Linux 10 ISO → extract packages → EROFS rootfs → initramfs → bootable ISO

1. Downloads Rocky Linux 10 ISO (9.3GB)
2. Extracts rootfs via unsquashfs
3. Copies binaries + library dependencies
4. Builds EROFS live filesystem
5. Creates busybox initramfs (~1MB)
6. Packages ISO with xorriso

What It Produces

File	Size	Description
output/levitateos-x86_64.iso	~800MB	Bootable ISO (UEFI + BIOS)
output/filesystem.erofs	~700MB	EROFS compressed root filesystem
output/initramfs-tiny.cpio.gz	~1MB	Busybox init + kernel modules

Sizes are approximate. Actual sizes depend on package selection.

Usage

cargo run -- build       # Full build (downloads 9.3GB Rocky ISO on first run)
cargo run -- run         # Boot in QEMU (GUI, UEFI)
cargo run -- preflight   # Check dependencies before building

Build Subcommands

cargo run -- build rootfs      # Build EROFS rootfs only
cargo run -- build initramfs   # Build initramfs only
cargo run -- build iso         # Build ISO only
cargo run -- build kernel      # Build kernel only

Download/Extract

cargo run -- download rocky    # Fetch Rocky ISO
cargo run -- download linux    # Fetch Linux kernel source
cargo run -- download tools    # Build/fetch recstrap, recfstab, recchroot
cargo run -- extract rocky     # Extract Rocky ISO contents
cargo run -- extract rootfs    # Extract rootfs for inspection

Other Commands

cargo run -- clean             # Remove build outputs (preserves downloads)
cargo run -- clean all         # Remove everything including downloads
cargo run -- show config       # Show current configuration
cargo run -- show rootfs       # List rootfs contents

Boot Sequence

1. systemd-boot loads UKI from /EFI/Linux/
2. UKI contains kernel + initramfs + cmdline
3. Busybox init mounts ISO, finds EROFS rootfs
4. Creates overlay: EROFS (ro) + tmpfs (rw)
5. switch_root to overlay
6. systemd starts as PID 1

Boot entries:

• levitateos-live.efi - Normal boot
• levitateos-emergency.efi - Emergency shell
• levitateos-debug.efi - Debug mode

Directory Layout

downloads/                       # Cached downloads (gitignored)
├── Rocky-10.1-x86_64-dvd1.iso   # 9.3GB
├── rootfs/                      # Extracted squashfs from Rocky
├── iso-contents/                # EFI files, kernel, etc.
├── linux/                       # Kernel source (git clone)
└── busybox-static               # Static busybox binary

output/                          # Build artifacts (gitignored)
├── filesystem.erofs             # EROFS compressed rootfs
├── initramfs-tiny.cpio.gz
├── initramfs-tiny-root/         # Initramfs staging directory
├── rootfs-staging/              # Rootfs staging directory
└── levitateos-x86_64.iso

profile/                         # Live system customization
├── init_tiny                    # Busybox init script
├── etc/                         # Config file overlays
├── live-overlay/                # Files overlaid on rootfs
└── root/                        # Root home directory overlay

Requirements

• Rust (edition 2021)
• unsquashfs (squashfs-tools)
• xorriso
• mkfs.erofs (erofs-utils 1.8+)
• ukify (systemd-ukify)
• systemd-boot
• 20GB free disk space

Known Issues

• Uses Rocky's kernel, not custom-built
• No secure boot support
• Kernel module selection is hardcoded
• WiFi firmware included but not tested on real hardware

License

MIT