rsinit is a minimalistic single binary init for the initramfs for embedded systems. It's main objective is to mount the root filesystem as fast as possible and then hand over to the actual init program.

The main use-case is, to mount root filesystems that cannot be mounted by the Linux kernel directly. But it can also mount just about anything that the kernel can mount directly based on the command-line.

Currently supported root filesystems are:

• 9pfs with USB gadget transport

• filesystems on a dm-verity device

• regular devices or anything that requires just specifying the device and mount options

• nfsroot

• 9pfs with virtio transport (for QEMU)

The project includes a Makefile for easy cross-compilation.

Before building, ensure you have the following tools installed:

• cross - Cross-compilation tool for Rust
• rustup - Rust toolchain manager
• podman or docker - Container runtime for cross
• cpio - For creating cpio/initramfs archives
• gzip - For compressing cpio/initramfs archives
• A nightly Rust toolchain

You can verify all dependencies are installed by running:

make check-toolchain

To see all available make targets and options:

make help

Common build commands:

# Build binaries and CPIO archives for all default targets
make all

# Build for a specific target only
make aarch64-unknown-linux-musl-build

# Create CPIO archive for a specific target
make aarch64-unknown-linux-musl-cpio

# Build with minimal profile (smaller binary size)
make MINIMAL_BUILD=1 all

# Use Docker instead of Podman
make CROSS_CONTAINER_ENGINE=docker all

Default target architectures:

• aarch64-unknown-linux-musl
• arm-unknown-linux-musleabihf
• x86_64-unknown-linux-musl

Build artifacts are placed in target/<arch>/<profile>/ directories.