sprout/README.md

Sprout

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Sprout is an EXPERIMENTAL programmable UEFI bootloader written in Rust.

Sprout is in use at Edera today in development environments and is intended to ship to production soon.

The name "sprout" is derived from our company name "Edera" which means "ivy." Given that Sprout is the first thing intended to start on an Edera system, the name was apt.

It supports x86_64 and ARM64 EFI-capable systems. It is designed to require UEFI and can be chainloaded from an existing UEFI bootloader or booted by the hardware directly.

Usage

Sprout is provided as a single EFI binary called sprout.efi. It can be chainloaded from GRUB or other UEFI bootloaders or booted into directly. Sprout will look for \sprout.toml in the root of the EFI partition it was loaded from. See Configuration for how to configure sprout.

Configuration

Sprout is configured using a TOML file at \sprout.toml on the root of the EFI partition sprout was booted from.

Boot Linux from ESP

# sprout configuration: version 1
version = 1

# add a boot entry for booting linux
# which will run the boot-linux action.
[entries.boot-linux]
title = "Boot Linux"
actions = ["boot-linux"]

# use the chainload action to boot linux via the efi stub.
# the options below are passed to the efi stub as the
# kernel command line. the initrd is loaded using the efi stub
# initrd loader mechanism.
[actions.boot-linux]
chainload.path = "\\vmlinuz"
chainload.options = ["root=/dev/sda1"]
chainload.linux-initrd = "\\initrd"

Bootloader Specification (BLS) Support

# sprout configuration: version 1
version = 1

# load an EFI driver for ext4.
[drivers.ext4]
path = "\\sprout\\drivers\\ext4.efi"

# extract the full path of the first filesystem
# that contains \loader\entries as a directory
# into the value called "boot"
[extractors.boot.filesystem-device-match]
has-item = "\\loader\\entries"

# use the sprout bls module to scan a bls
# directory for entries and load them as boot
# entries in sprout, using the entry template
# as specified here. the bls action below will
# be passed the extracted values from bls.
[generators.boot.bls]
path = "$boot\\loader\\entries"
entry.title = "$title"
entry.actions = ["bls"]

# the action that is used for each bls entry above.
[actions.bls]
chainload.path = "$boot\\$chainload"
chainload.options = ["$options"]
chainload.linux-initrd = "$boot\\$initrd"