# Sprout Development Guide

This guide is a work in progress.

## Development Setup

You can use any Rust development environment to develop Sprout.
Rustup is recommended as the Rust toolchain manager to manage Rust versions and targets.
We currently only support `x86_64-unknown-uefi` and `aarch64-unknown-uefi` targets.

To test your changes in QEMU, please run `./hack/dev/boot.sh`, you can specify `x86_64` or `aarch64`
as an argument to boot.sh to boot the specified architecture.

## Crate Structure

Sprout is split into multiple crates:

- `edera-sprout-boot` at `crates/boot`: Bootloader entrypoint for Sprout.
- `edera-sprout-bls` at `crates/bls`: Parsing and sorting of Boot Loader Specification entries.
- `edera-sprout-build` at `crates/build`: Build logic for Sprout.
- `edera-sprout-config` at `crates/config`: Serialization structures for the Sprout configuration file.
- `edera-sprout-eficore` at `crates/eficore`: Core library for Sprout EFI code.
- `edera-sprout-parsing` at `crates/parsing`: Value stamping and other parsing helpers for Sprout.

It is intended that overtime Sprout will be split into even more crates.

## Hack Scripts

You can use the `./hack` scripts to run common development tasks:

### ./hack/build.sh

Builds the Sprout binary for the target that would support your current machine.

### ./hack/assemble.sh

Builds both x86_64 and aarch64 binaries into `target/assemble`.

### ./hack/clean.sh

Cleans the target directory and any docker images that were built.

### ./hack/format.sh

Formats the code using `rustfmt` and shell scripts with `shfmt`.

### ./hack/autofix.sh

Applies Clippy and `rustfmt` fixes to the code, and formats shell scripts with `shfmt`.

## Dev Scripts

### ./hack/dev/build.sh

Build Sprout as OCI images using Docker, including a kernel, initramfs, xen, and other supporting files.

### ./hack/dev/boot.sh

Boot Sprout's dev environment using QEMU for testing. This will let you test your changes in a real environment booting
Alpine Linux with an initramfs.

### ./hack/dev/run

Scripts to drive the dev environment without a terminal or a window, which suits automation and
coding agents. QEMU runs in the background with a QMP socket, and its consoles are written to
`target/run/<arch>/`. Only one run per architecture at a time, and the scripts need `python3` or `socat`.

- `start.sh [arch]`: Builds and starts QEMU headless. `SPROUT_CONFIG_NAME` defaults to `graphical`.
- `screenshot.sh [out.png]`: Saves a PNG of the display (QEMU 7.1 or newer) and prints the path.
- `key.sh <qcode>...`: Presses keys such as `down`, `up`, `ret` or `ctrl+alt+delete`.
- `wait-serial.sh <regex> [seconds]`: Waits for text on the firmware or Linux console.
- `qmp.sh <json>...`: Sends raw QMP commands.
- `status.sh` and `stop.sh`: Show the state of QEMU, and stop it.
- `smoke.sh [arch]`: Starts, drives the graphical menu, waits for the Linux shell and stops.

`boot.sh` supports this with `QEMU_HEADLESS`, `QEMU_QMP`, `QEMU_SERIAL_FILE`, `QEMU_CONSOLE_FILE` and `QEMU_EXTRA_ARGS`.