omnect-os-init

Rust-based init process for omnect-os initramfs.

Overview

Replaces 14 bash-based initramfs scripts (~1500 LOC) with a single Rust binary acting as /init in the initramfs. Runs as PID 1 before switch_root.

Implemented functionality:

• Bootloader abstraction: Unified Bootloader trait for GRUB (grub-editenv) and U-Boot (fw_printenv/fw_setenv); fsck output persisted across reboots as gzip+base64 in the bootloader env (encoded via busybox gzip/base64 — no crate dependencies)
• Configuration: Parses /proc/cmdline; build-time constants from Yocto environment via build.rs
• Partition management: Root device detection, partition layout (GPT/DOS), /dev/omnect/* symlinks
• Filesystem operations: fsck, mount manager (RAII), overlayfs for /etc and /home, bind mounts
• Logging: Kernel ring buffer (/dev/kmsg) with log level prefixes
• ODS integration: Runtime files for omnect-device-service
• fs-links: Symlink creation from etc/omnect/fs-link.json and etc/omnect/fs-link.d/
• switch_root: MS_MOVE + chroot + exec systemd (pivot_root(2) is not used; ramfs does not support it)

Not yet implemented (planned):

• Factory reset (backup, wipe, restore)
• Flash modes (disk clone, network, HTTP/HTTPS)
• Data partition auto-resize

Building

# Debug build (bootloader type must be specified)
cargo build --features grub     # x86-64 EFI targets
cargo build --features uboot    # ARM targets

# Release build (optimized for size)
cargo build --release --features grub
cargo build --release --features uboot

# With additional optional features
cargo build --release --features "grub,persistent-var-log"

Features

Feature	Description	Status
core	Core boot sequence (default)	Implemented
grub	GRUB bootloader support — x86-64 EFI targets	Implemented
uboot	U-Boot bootloader support — ARM targets	Implemented
gpt	GPT partition table layout	Implemented
dos	DOS/MBR partition table layout	Implemented
persistent-var-log	Bind-mount /var/log to data partition	Implemented
release-image	Release error handling (loop on fatal error)	Implemented
factory-reset	Factory reset support	Planned
flash-mode-1	Disk cloning	Planned
flash-mode-2	Network flashing	Planned
flash-mode-3	HTTP/HTTPS flashing	Planned
resize-data	Data partition auto-resize	Planned

Note: grub and uboot are mutually exclusive. Exactly one must be set at build time. The Yocto recipe selects the correct feature via CARGO_FEATURES based on MACHINE_FEATURES.

Testing

# All four valid feature combinations (bootloader × partition table)
cargo test --features grub,gpt   # x86-64 targets, GPT
cargo test --features grub,dos   # x86-64 targets, DOS/MBR
cargo test --features uboot,gpt  # ARM targets, GPT
cargo test --features uboot,dos  # ARM targets, DOS/MBR

# Verbose output
cargo test --features grub,gpt -- --nocapture

Architecture

src/
├── main.rs                  # Entry point (PID 1)
├── lib.rs                   # Library exports
├── error.rs                 # Error type hierarchy
├── early_init.rs            # Mount /dev, /proc, /sys, /run before logging
├── bootloader/
│   ├── mod.rs               # Bootloader trait + build-time selection (grub/uboot feature)
│   ├── grub.rs              # GRUB implementation (grub-editenv)
│   ├── uboot.rs             # U-Boot implementation (fw_printenv/fw_setenv)
│   └── types.rs             # BootloaderType enum
├── config/
│   └── mod.rs               # /proc/cmdline parser; build-time constants via build.rs
├── filesystem/
│   ├── mod.rs               # Public API
│   ├── boot_sequence.rs     # Mount + fsck orchestration (testable with mock bootloaders)
│   ├── fsck.rs              # e2fsck wrapper (all exit codes handled)
│   ├── mount.rs             # Mount primitives (RAII, idempotency checks)
│   └── overlayfs.rs         # /etc overlay, /home overlay, bind mounts
├── logging/
│   ├── mod.rs               # KmsgLogger initializer
│   └── kmsg.rs              # /dev/kmsg writer with kernel log levels
├── partition/
│   ├── mod.rs               # Public API
│   ├── device.rs            # Root device detection (GRUB: blkid/fsuuid, U-Boot: root=)
│   ├── layout.rs            # GPT/DOS partition map builder
│   └── symlinks.rs          # /dev/omnect/* symlink creation
└── runtime/
    ├── mod.rs               # Public API
    ├── fs_link.rs           # fs-link symlink creation
    ├── omnect_device_service.rs  # ODS JSON status file writer
    └── switch_root.rs       # MS_MOVE new root to / + chroot + exec init

License

MIT OR Apache-2.0