init.c

init.c replaces Bedrock Linux's shell-based init (/bedrock/strata/bedrock/sbin/init) with a minimal C + x86_64 ASM static binary. It does the same job: pivot into the chosen stratum, enable all strata, hand off to the real init, but it's ~10%* faster than Bedrock Linux's init.

Why init.c?

Bedrock Linux's init is a shell script. At every boot it:

• Forks subprocesses for grep, awk, sed, realpath, mount
• Enables strata sequentially — one at a time, each taking several seconds
• Pipes data through chains of shell utilities

init.c replaces all of that with direct syscalls and parallel stratum enablement. The result: the slowest single stratum sets the wall clock, not the sum of all of them.

How it works

main()
├── check_pid1()           → if not PID 1, exec backup immediately
├── ensure_essential_env() → mount /proc, /sys, /dev, /run
├── setup_term()           → configure TTY, kill plymouth
├── print_logo()           → Bedrock ASCII art
├── parse_bedrock_conf()   → read [init] section from bedrock.conf
├── scan_strata()          → list /bedrock/strata/*
├── run_menu()             → interactive stratum/init selection
├── mount_fstab()          → dmsetup, lvm, mount -a (direct syscalls)
├── pivot_root_to()        → bind-mount stratum + pivot_root
├── preenable_mounts()     → rbind /proc, /dev, /sys, /run
├── enable_strata_parallel() → fork ALL strata at once
│   ├── brl-repair bedrock (foreground)
│   ├── brl-repair <init>  (foreground)
│   └── brl-enable <N>…   (parallel — one child per stratum)
├── brl-apply              → apply configuration (forked)
└── execv(<real init>)     → PID 1 hands off, never returns

Key design decisions

• Statically linked — no libc.so dependency; safe to run before ld.so is set up
• Direct syscalls — mount(2), pivot_root(2), open(2)/read(2) for everything; no system(), no popen()
• Parallel enable — all strata except bedrock and the init stratum are brl-enable'd simultaneously via fork() + waitpid(-1)
• x86_64 ASM helpers — asm_memzero, asm_strcmp, asm_write_str for hot paths and async-signal-safe panic output
• No runtime downloads — the Makefile never fetches files during install; make install-fallback is a separate manual step

Dependencies

Build-time

Tool	Purpose
gcc	C compilation
nasm	Assembly
ld	Linking (binutils)
static attr	Handles fs objects

All must target x86_64 Linux. The binary is statically linked and has no runtime library dependencies.

Runtime

• Bedrock Linux system with /bedrock/strata/* strata directories
• /bedrock/libexec/brl-repair, /bedrock/libexec/brl-enable, /bedrock/libexec/brl-apply
• Kernel with pivot_root(2) support

Installation

1. Build

make

Produces build/init (stripped, ~850KB ELF64).

2. Install

sudo make install

This will:

1. Back up the existing init at /bedrock/strata/bedrock/sbin/init → .sh.bak (shell script) or .bin.bak (binary)
2. Copy the backup to /sbin/init as a recovery fallback
3. Place the init.c binary at /bedrock/strata/bedrock/sbin/init

3. Fallback (optional)

If there was no existing init to back up, or you want a fresh copy of the official Bedrock init:

sudo make install-fallback

Downloads the official Bedrock Linux shell init and saves it as both the .sh.bak backup and /sbin/init.

4. Debug build

make debug

Produces build/init.debug with -g3 and AddressSanitizer (unstripped).

5. Verify

make check

Validates ELF type, static linking, forbidden symbols, and ASM symbol presence.

Booting

On next reboot:

1. init.c starts as PID 1
2. Mounts essential filesystems (/proc, /sys, /dev, /run)
3. Reads /bedrock/etc/bedrock.conf for init selection
4. Presents an interactive menu of available stratum/init combinations (with configurable timeout)
5. Pivots root into the chosen stratum
6. Enables all show_boot strata in parallel
7. Handles control to the stratum's real init via execv()

Kernel command-line shortcut

bedrock_init=stratum:/sbin/init

Skips the menu entirely.

Contributing

Contributions are welcome via pull request.

1. Fork the repository
2. Create a feature branch (git checkout -b feature/my-change)
3. Make your changes
4. Build and verify (make clean && make && make check)
5. Commit with a descriptive message
6. Open a pull request

Code conventions

• C11 with GNU extensions (-std=c11 -D_GNU_SOURCE)
• No system(), popen(), or dynamic library calls
• Direct write(2) for output in signal-safe paths
• Static helper functions where possible
• Follow the existing style (Allman brace style, descriptive variable names)

License

GPL-v3.

Note

*: May or may not be 10% all the time, but the boot speed was 18.42 seconds on my machine

init.c was built and tested the most on ENux 5.3.3. If you want to use this init on other systems, be cautious as they haven't been tested yet.

init.c will be the default init for ENux soon.

All of the benchmarks, like timing, strata boot speeds and more, have been tested on a 7 strata ENux system.

The system to test init.c consists of:

• i5 12400f (12 processing units)
• 32 GB DDR5 6000 MHz CL30
• Gen 4 NVME (with read/write speeds of around 5000/3500 MBs)