sprout: version 0.0.8

Bump toml from 0.9.7 to 0.9.8 in the cargo-updates group

.github/codeql/codeql-config.yaml

@@ -0,0 +1,5 @@
+name: "codeql-config"
+
+extractor-options:
+  rust:
+    cargo_target: x86_64-unknown-uefi

.github/dependabot.yaml

@@ -26,3 +26,16 @@ updates:
     cargo-dev-updates:
       dependency-type: development
       applies-to: version-updates
+- package-ecosystem: docker
+  directory: /
+  schedule:
+    interval: weekly
+  cooldown:
+    default-days: 7
+  groups:
+    docker-updates:
+      dependency-type: production
+      applies-to: version-updates
+    docker-dev-updates:
+      dependency-type: development
+      applies-to: version-updates

.github/workflows/ci-code.yaml

@@ -26,10 +26,9 @@ jobs:
       with:
         persist-credentials: false
 
-    - name: 'install nightly rust toolchain with rustfmt'
+    - name: 'install rust toolchain with rustfmt'
       run: |
-        rustup update --no-self-update nightly
-        rustup default nightly
+        cargo version
         rustup component add rustfmt
 
     - name: 'cargo fmt'
@@ -57,10 +56,9 @@ jobs:
       with:
         persist-credentials: false
 
-    - name: 'install nightly rust toolchain'
+    - name: 'install rust toolchain'
       run: |
-        rustup update --no-self-update nightly
-        rustup default nightly
+        cargo version
 
     - name: cargo build
       run: cargo build --target "${TARGET_ARCH}-unknown-uefi"
@@ -87,10 +85,9 @@ jobs:
       with:
         persist-credentials: false
 
-    - name: 'install nightly rust toolchain with clippy'
+    - name: 'install rust toolchain with clippy'
       run: |
-        rustup update --no-self-update nightly
-        rustup default stable
+        cargo version
         rustup component add clippy
 
     - name: cargo clippy

.github/workflows/codeql.yaml

@@ -0,0 +1,53 @@
+name: codeql
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+  schedule:
+  - cron: '33 16 * * 0'
+
+permissions:
+  contents: read # Needed to checkout the repository.
+
+jobs:
+  analyze:
+    name: analyze (${{ matrix.language }})
+    runs-on: 'ubuntu-latest'
+    permissions:
+      security-events: write # Needed to upload results.
+      packages: read # Needed to fetch internal or private CodeQL packs.
+      actions: read # Needed to read workflows.
+      contents: read # Needed to checkout the repository.
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+        - language: actions
+          build-mode: none
+        - language: rust
+          build-mode: none
+    steps:
+    - name: harden runner
+      uses: step-security/harden-runner@f4a75cfd619ee5ce8d5b864b0d183aff3c69b55a # v2.13.1
+      with:
+        egress-policy: audit
+
+    - name: checkout
+      uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+      with:
+        persist-credentials: false
+
+    - name: initialize codeql
+      uses: github/codeql-action/init@16140ae1a102900babc80a33c44059580f687047 #v4
+      with:
+        languages: ${{ matrix.language }}
+        build-mode: ${{ matrix.build-mode }}
+        config-file: ./.github/codeql/codeql-config.yaml
+
+    - name: perform codeql analysis
+      uses: github/codeql-action/analyze@16140ae1a102900babc80a33c44059580f687047 #v4
+      with:
+        category: "/language:${{matrix.language}}"

.github/workflows/publish.yaml

@@ -1,9 +1,12 @@
 name: publish
 
 on:
-  release:
-    types:
-    - created
+  workflow_dispatch:
+    inputs:
+      release-tag:
+        description: 'Release Tag'
+        required: true
+        type: string
 
   push:
     branches:
@@ -39,10 +42,9 @@ jobs:
       with:
         persist-credentials: false
 
-    - name: 'install nightly rust toolchain'
+    - name: 'install rust toolchain'
       run: |
-        rustup update --no-self-update nightly
-        rustup default nightly
+        cargo version
 
     - name: 'assemble artifacts'
       run: ./hack/assemble.sh
@@ -65,10 +67,18 @@ jobs:
       with:
         app-id: "${{ secrets.EDERA_CULTIVATION_APP_ID }}"
         private-key: "${{ secrets.EDERA_CULTIVATION_APP_PRIVATE_KEY }}"
+      if: ${{ github.event.inputs.release-tag != '' }}
 
     - name: 'upload release artifacts'
       run: ./hack/ci/upload-release-assets.sh
       env:
         GITHUB_TOKEN: "${{ steps.generate-token.outputs.token }}"
-        RELEASE_TAG: "${{ github.event.release.tag_name }}"
-      if: ${{ github.event_name == 'release' }}
+        RELEASE_TAG: "${{ github.event.inputs.release-tag }}"
+      if: ${{ github.event.inputs.release-tag != '' }}
+
+    - name: 'mark release as published'
+      run: gh release edit "${RELEASE_TAG}" --draft=false --verify-tag
+      env:
+        GITHUB_TOKEN: "${{ steps.generate-token.outputs.token }}"
+        RELEASE_TAG: "${{ github.event.inputs.release-tag }}"
+      if: ${{ github.event.inputs.release-tag != '' }}

Cargo.lock

@@ -61,7 +61,7 @@ dependencies = [
 
 [[package]]
 name = "edera-sprout"
-version = "0.0.4"
+version = "0.0.8"
 dependencies = [
  "anyhow",
  "image",
@@ -252,9 +252,9 @@ dependencies = [
 
 [[package]]
 name = "serde_spanned"
-version = "1.0.2"
+version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5417783452c2be558477e104686f7de5dae53dba813c28435e0e70f82d9b04ee"
+checksum = "e24345aa0fe688594e73770a5f6d1b216508b4f93484c0026d521acd30134392"
 dependencies = [
  "serde_core",
 ]
@@ -277,9 +277,9 @@ dependencies = [
 
 [[package]]
 name = "toml"
-version = "0.9.7"
+version = "0.9.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "00e5e5d9bf2475ac9d4f0d9edab68cc573dc2fd644b0dba36b0c30a92dd9eaa0"
+checksum = "f0dc8b1fb61449e27716ec0e1bdf0f6b8f3e8f6b05391e8497b8b6d7804ea6d8"
 dependencies = [
  "indexmap",
  "serde_core",
@@ -292,27 +292,27 @@ dependencies = [
 
 [[package]]
 name = "toml_datetime"
-version = "0.7.2"
+version = "0.7.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32f1085dec27c2b6632b04c80b3bb1b4300d6495d1e129693bdda7d91e72eec1"
+checksum = "f2cdb639ebbc97961c51720f858597f7f24c4fc295327923af55b74c3c724533"
 dependencies = [
  "serde_core",
 ]
 
 [[package]]
 name = "toml_parser"
-version = "1.0.3"
+version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4cf893c33be71572e0e9aa6dd15e6677937abd686b066eac3f8cd3531688a627"
+checksum = "c0cbe268d35bdb4bb5a56a2de88d0ad0eb70af5384a99d648cd4b3d04039800e"
 dependencies = [
  "winnow",
 ]
 
 [[package]]
 name = "toml_writer"
-version = "1.0.3"
+version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d163a63c116ce562a22cda521fcc4d79152e7aba014456fb5eb442f6d6a10109"
+checksum = "df8b2b54733674ad286d16267dcfc7a71ed5c776e4ac7aa3c3e2561f7c637bf2"
 
 [[package]]
 name = "ucs2"

Cargo.toml

@@ -2,14 +2,14 @@
 name = "edera-sprout"
 description = "Modern UEFI bootloader"
 license = "Apache-2.0"
-version = "0.0.4"
+version = "0.0.8"
 homepage = "https://sprout.edera.dev"
 repository = "https://github.com/edera-dev/sprout"
 edition = "2024"
 
 [dependencies]
 anyhow = "1.0.100"
-toml = "0.9.7"
+toml = "0.9.8"
 log = "0.4.28"
 
 [dependencies.image]

Dockerfile

@@ -2,7 +2,7 @@
 ARG RUST_PROFILE=release
 ARG RUST_TARGET_SUBDIR=release
 
-FROM --platform=$BUILDPLATFORM rustlang/rust:nightly-alpine@sha256:b8107fa66d3e5ad7f729d3347c7feedbd3f4b60b01006edce39eb6b994ff00bd AS build
+FROM --platform=$BUILDPLATFORM rustlang/rust:nightly-alpine@sha256:141e9a7f13f77237dd4d462364c3a1b21cb8a6791d8924c409573e77b788af5e AS build
 RUN apk --no-cache add musl-dev busybox-static
 ARG RUST_PROFILE
 RUN adduser -S -s /bin/sh build

README.md

@@ -18,6 +18,34 @@ existing UEFI bootloader or booted by the hardware directly.
 
 Sprout is licensed under Apache 2.0 and is open to modifications and contributions.
 
+## Background
+
+At [Edera] we make compute isolation technology for a wide variety of environments, often ones we do not fully control.
+Our technology utilizes a hypervisor to boot the host system to provide a new isolation mechanism that works
+with or without hardware virtualization support. To do this we need to inject our hypervisor at boot time.
+
+Unfortunately, GRUB, the most common bootloader on Linux systems today, utilizes a shell-script like
+configuration system. Both the code that runs to generate a GRUB config and the GRUB config
+itself is fully turing complete. This makes modifying boot configuration difficult and error-prone.
+
+Sprout was designed to take in a machine-readable, writable, and modifiable configuration that treats boot information
+like data plus configuration, and can be chained from both UEFI firmware and GRUB alike.
+
+Sprout aims to be flexible, secure, and modern. Written in Rust, it handles data safely and uses unsafe code as little
+as possible. It also critically must be easy to install into all common distributions, relying on simple principles to
+simplify installation and usage.
+
+## Documentation
+
+- [Fedora Setup Guide]
+- [Generic Linux Setup Guide]
+- [Windows Setup Guide]
+- [Development Guide]
+- [Contributing Guide]
+- [Sprout License]
+- [Code of Conduct]
+- [Security Policy]
+
 ## Features
 
 NOTE: Currently, Sprout is experimental and is not intended for production use. For example, it doesn't currently
@@ -29,6 +57,7 @@ have secure boot support. In fact, as of writing, it doesn't even have a boot me
 - [x] [Bootloader specification (BLS)](https://uapi-group.org/specifications/specs/boot_loader_specification/) support
 - [x] Chainload support
 - [x] Linux boot support via EFI stub
+- [x] Windows boot support via chainload
 - [x] Load Linux initrd from disk
 - [x] Boot first configured entry
 
@@ -37,7 +66,6 @@ have secure boot support. In fact, as of writing, it doesn't even have a boot me
 - [ ] Boot menu
 - [ ] Secure Boot support: work in progress
 - [ ] UKI support: partial
-- [ ] Windows boot support (untested via chainload)
 - [ ] multiboot2 support
 - [ ] Linux boot protocol (boot without EFI stub)
 
@@ -62,6 +90,17 @@ See [Configuration](#configuration) for how to configure sprout.
 
 Sprout is configured using a TOML file at `\sprout.toml` on the root of the EFI partition sprout was booted from.
 
+### Command Line Options
+
+Sprout supports some command line options that can be combined to modify behavior without the configuration file.
+
+```bash
+# Boot Sprout with a specific configuration file.
+$ sprout.efi --config=\path\to\config.toml
+# Boot a specific entry, bypassing the menu.
+$ sprout.efi --boot="Boot Xen"
+```
+
 ### Boot Linux from ESP
 
 ```toml
@@ -116,3 +155,13 @@ chainload.path = "$boot\\$chainload"
 chainload.options = ["$options"]
 chainload.linux-initrd = "$boot\\$initrd"
 ```
+
+[Edera]: https://edera.dev
+[Fedora Setup Guide]: ./docs/fedora-setup.md
+[Generic Linux Setup Guide]: ./docs/generic-linux-setup.md
+[Windows Setup Guide]: ./docs/windows-setup.md
+[Development Guide]: ./DEVELOPMENT.md
+[Contributing Guide]: ./CONTRIBUTING.md
+[Sprout License]: ./LICENSE
+[Code of Conduct]: ./CODE_OF_CONDUCT.md
+[Security Policy]: ./SECURITY.md

docs/fedora-setup.md

@@ -0,0 +1,134 @@
+# Setup Sprout on Fedora
+
+## Prerequisites
+
+- Modern Fedora release: tested on Fedora Workstation 42 and 43
+- EFI System Partition mounted on `/boot/efi` (the default)
+- ext4 or FAT32/exFAT formatted `/boot` partition
+
+## Step 1: Base Installation
+
+Download the latest sprout.efi release from the [GitHub releases page](https://github.com/edera-dev/sprout/releases).
+For x86_64 systems, download the `sprout-x86_64.efi` file, and for ARM systems, download the `sprout-aarch64.efi` file.
+Copy the downloaded `sprout.efi` file to `/boot/efi/EFI/BOOT/sprout.efi` on your EFI System Partition.
+
+Additionally, you will want to install the `edk2-ext4` package, which provides the ext4 filesystem support for Sprout.
+
+```bash
+# Install the edk2-ext4 package which provides ext4 support for Sprout.
+$ sudo dnf install edk2-ext4
+# Create a directory for sprout drivers.
+$ sudo mkdir -p /boot/efi/sprout/drivers
+# For x86_64 systems, copy the ext4x64.efi driver to the sprout drivers directory.
+$ sudo cp /usr/share/edk2/drivers/ext4x64.efi /boot/efi/sprout/drivers/ext4.efi
+# For ARM64 systems, copy the ext4aa64.efi driver to the sprout drivers directory.
+$ sudo cp /usr/share/edk2/drivers/ext4aa64.efi /boot/efi/sprout/drivers/ext4.efi
+```
+
+## Step 2: Configure Sprout
+
+Since Fedora uses the BLS specification, you can use the `bls` generator to autoconfigure Sprout for Fedora.
+
+Write the following file to `/boot/efi/sprout.toml`:
+
+```toml
+# 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"
+```
+
+## Step 3, Option 1: Configure GRUB to load Sprout (recommended)
+
+You can configure GRUB to add a boot entry for Sprout, so you can continue to use GRUB without interruption.
+
+GRUB needs to be configured with the chainloader module to load Sprout.
+
+### x86_64
+
+```bash
+# Install x86_64 GRUB modules.
+$ sudo dnf install grub2-efi-x64-modules
+# Copy x86_64 GRUB modules to /boot/grub2 for use by GRUB if it isn't installed already.
+$ [ ! -d /boot/grub2/x86_64-efi ] && sudo cp -r /usr/lib/grub/x86_64-efi /boot/grub2/x86_64-efi
+```
+
+### ARM64
+
+```bash
+# Install ARM64 GRUB modules.
+$ sudo dnf install grub2-efi-aa64-modules
+# Copy ARM64 GRUB modules to /boot/grub2 for use by GRUB if it isn't installed already.
+$ [ ! -d /boot/grub2/arm64-efi ] && sudo cp -r /usr/lib/grub/arm64-efi /boot/grub2/x86_64-efi
+```
+
+You will need to find the UUID of your EFI System Partition. You can do this by running the following command:
+```bash
+$ grep "/boot/efi" /etc/fstab | awk '{print $1}' | awk -F '=' '{print $2}'
+SAMPLE-VALUE
+```
+
+The GRUB configuration for Sprout is as follows, replace `SAMPLE-VALUE` with the UUID of your EFI System Partition:
+
+```grub
+menuentry 'Sprout' $menuentry_id_option 'sprout' {
+        insmod part_gpt
+        insmod fat
+        insmod chain
+        search --no-floppy --fs-uuid --set=root SAMPLE-VALUE
+        chainloader /EFI/BOOT/sprout.efi
+}
+```
+
+You can append this to `/etc/grub.d/40_custom` and run the following command to update your configuration:
+```bash
+$ sudo grub2-mkconfig -o /boot/grub2/grub.cfg
+```
+
+To update your GRUB configuration.
+
+Make sure to update your GRUB environment to show the menu:
+
+```bash
+$ sudo grub2-editenv - set menu_auto_hide=0
+```
+
+You may now reboot your system and select Sprout from the GRUB menu.
+
+## Step 3, Option 2: Configure your EFI firmware for Sprout
+
+You can configure your EFI boot menu to show Sprout as an option.
+
+To do so, please find the partition device of your EFI System Partition and run the following:
+
+```bash
+$ sudo efibootmgr -d /dev/esp_partition_here -C -L 'Sprout' -l '\EFI\BOOT\sprout.efi'
+```
+
+This will add a new entry to your EFI boot menu called `Sprout` that will boot Sprout with your configuration.
+
+Now if you boot into your UEFI firmware, you should see Sprout as an option to boot.

docs/generic-linux-setup.md

@@ -0,0 +1,62 @@
+# Setup Sprout to boot Linux
+
+## Prerequisites
+
+- EFI System Partition mounted on a known path
+- Linux kernel installed with an optional initramfs
+- Linux kernel must support the EFI stub (most distro kernels)
+
+## Step 1: Base Installation
+
+First, identify the path to your EFI System Partition. On most systems, this is `/boot/efi`.
+
+Download the latest sprout.efi release from the [GitHub releases page](https://github.com/edera-dev/sprout/releases).
+For x86_64 systems, download the `sprout-x86_64.efi` file, and for ARM systems, download the `sprout-aarch64.efi` file.
+Copy the downloaded `sprout.efi` file to `/EFI/BOOT/sprout.efi` on your EFI System Partition.
+
+## Step 2: Copy kernel and optional initramfs
+
+Copy the Linux kernel to `/vmlinuz-sprout` on your EFI System Partition.
+If needed, copy the initramfs to `/initramfs-sprout` on your EFI System Partition.
+
+## Step 3: Configure Sprout
+
+Write the following file to `/sprout.toml` on your EFI System Partition,
+paying attention to place the correct values:
+
+```toml
+# 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-sprout"
+chainload.options = ["root=/dev/sda1", "my-kernel-option"]
+chainload.linux-initrd = "\\initramfs-sprout"
+```
+
+You can specify any kernel command line options you want on the chainload options line.
+They will be concatenated by a space and passed to the kernel.
+
+## Step 4: Configure EFI firmware to boot Sprout
+
+Since Sprout is still experimental, the following commands will add a boot entry to your EFI firmware for sprout but
+intentionally do not set it as the default boot entry.
+
+To add the entry, please find the partition device of your EFI System Partition and run the following:
+
+```bash
+$ sudo efibootmgr -d /dev/esp_partition_here -C -L 'Sprout' -l '\EFI\BOOT\sprout.efi'
+```
+
+This will add a new entry to your EFI boot menu called `Sprout` that will boot Sprout with your configuration.
+Now if you boot into your UEFI firmware, you should see Sprout as an option to boot.

docs/windows-setup.md

@@ -0,0 +1,52 @@
+# Setup Sprout to boot Windows
+
+## Prerequisites
+
+- Secure Boot disabled
+- UEFI Windows installation
+
+## Step 1: Base Installation
+
+First, mount the EFI System Partition on your Windows installation:
+
+In an administrator command prompt, run:
+
+```batch
+> mountvol X: /s
+```
+
+This will mount the EFI System Partition to the drive letter `X:`.
+
+Please note that Windows Explorer will not let you see the drive letter `X:` where the ESP is mounted.
+You will need to use the command prompt or PowerShell to access the ESP.
+Standard editors can, however, be used to edit files on the ESP.
+
+Download the latest sprout.efi release from the [GitHub releases page](https://github.com/edera-dev/sprout/releases).
+For x86_64 systems, download the `sprout-x86_64.efi` file, and for ARM systems, download the `sprout-aarch64.efi` file.
+Copy the downloaded `sprout.efi` file to `X:\EFI\BOOT\sprout.efi` on your EFI System Partition.
+
+## Step 3: Configure Sprout
+
+Write the following file to `X:\sprout.toml`:
+
+```toml
+# sprout configuration: version 1
+version = 1
+
+# add a boot entry for booting Windows
+# which will run the boot-windows action.
+[entries.windows]
+title = "Windows"
+actions = ["boot-windows"]
+
+# use the chainload action to boot the Windows bootloader.
+[actions.boot-windows]
+chainload.path = "\\EFI\\Microsoft\\Boot\\bootmgfw.efi"
+```
+
+## Step 4: Configure EFI Firmware to boot Sprout
+
+It is not trivial to add an EFI boot entry inside Windows.
+However, most firmware lets you load arbitrary EFI files from the firmware settings.
+
+You can boot `\EFI\BOOT\sprout.efi` from firmware to boot Sprout.

hack/common.sh

@@ -41,3 +41,8 @@ if [ -z "${QEMU_ACCEL}" ] && [ "${TARGET_ARCH}" = "${HOST_ARCH}" ] &&
 	grep -E '^flags.*:.+ vmx .*' /proc/cpuinfo >/dev/null; then
 	QEMU_ACCEL="kvm"
 fi
+
+if [ "$(uname)" = "Darwin" ] && [ "${TARGET_ARCH}" = "${HOST_ARCH}" ] &&
+	[ "$(sysctl -n kern.hv_support 2>&1 || true)" = "1" ]; then
+	QEMU_ACCEL="hvf"
+fi

hack/dev/boot.sh

@@ -19,7 +19,7 @@ elif [ "${TARGET_ARCH}" = "aarch64" ]; then
 fi
 
 if [ -n "${QEMU_ACCEL}" ]; then
-	set -- "${@}" "-accel" "kvm"
+	set -- "${@}" "-accel" "${QEMU_ACCEL}"
 fi
 
 if [ "${QEMU_GDB}" = "1" ]; then

hack/dev/configs/shell.sprout.toml

@@ -0,0 +1,11 @@
+version = 1
+
+[extractors.boot.filesystem-device-match]
+has-item = "\\EFI\\BOOT\\shell.efi"
+
+[actions.chainload-shell]
+chainload.path = "$boot\\EFI\\BOOT\\shell.efi"
+
+[entries.xen]
+title = "Boot Shell"
+actions = ["chainload-shell"]

src/config/loader.rs

@@ -1,31 +1,36 @@
 use crate::config::{RootConfiguration, latest_version};
+use crate::options::SproutOptions;
 use crate::utils;
 use anyhow::{Context, Result, bail};
+use log::info;
 use std::ops::Deref;
 use toml::Value;
 use uefi::proto::device_path::LoadedImageDevicePath;
 
-/// Loads the raw configuration from the sprout.toml file as data.
-fn load_raw_config() -> Result<Vec<u8>> {
+/// Loads the raw configuration from the sprout config file as data.
+fn load_raw_config(options: &SproutOptions) -> Result<Vec<u8>> {
     // Open the LoadedImageDevicePath protocol to get the path to the current image.
     let current_image_device_path_protocol =
         uefi::boot::open_protocol_exclusive::<LoadedImageDevicePath>(uefi::boot::image_handle())
             .context("unable to get loaded image device path")?;
     // Acquire the device path as a boxed device path.
     let path = current_image_device_path_protocol.deref().to_boxed();
-    // Read the contents of the sprout.toml file.
-    let content = utils::read_file_contents(&path, "sprout.toml")
-        .context("unable to read sprout.toml file")?;
-    // Return the contents of the sprout.toml file.
+
+    info!("configuration file: {}", options.config);
+
+    // Read the contents of the sprout config file.
+    let content = utils::read_file_contents(&path, &options.config)
+        .context("unable to read sprout config file")?;
+    // Return the contents of the sprout config file.
     Ok(content)
 }
 
 /// Loads the [RootConfiguration] for Sprout.
-pub fn load() -> Result<RootConfiguration> {
-    // Load the raw configuration from the sprout.toml file.
-    let content = load_raw_config()?;
+pub fn load(options: &SproutOptions) -> Result<RootConfiguration> {
+    // Load the raw configuration from the sprout config file.
+    let content = load_raw_config(options)?;
     // Parse the raw configuration into a toml::Value which can represent any TOML file.
-    let value: Value = toml::from_slice(&content).context("unable to parse sprout.toml file")?;
+    let value: Value = toml::from_slice(&content).context("unable to parse sprout config file")?;
 
     // Check the version of the configuration without parsing the full configuration.
     let version = value

src/context.rs

@@ -1,4 +1,5 @@
 use crate::actions::ActionDeclaration;
+use crate::options::SproutOptions;
 use anyhow::Result;
 use anyhow::anyhow;
 use std::collections::{BTreeMap, BTreeSet};
@@ -13,15 +14,18 @@ pub struct RootContext {
     actions: BTreeMap<String, ActionDeclaration>,
     /// The device path of the loaded Sprout image.
     loaded_image_path: Option<Box<DevicePath>>,
+    /// The global options of Sprout.
+    options: SproutOptions,
 }
 
 impl RootContext {
     /// Creates a new root context with the `loaded_image_device_path` which will be stored
     /// in the context for easy access.
-    pub fn new(loaded_image_device_path: Box<DevicePath>) -> Self {
+    pub fn new(loaded_image_device_path: Box<DevicePath>, options: SproutOptions) -> Self {
         Self {
             actions: BTreeMap::new(),
             loaded_image_path: Some(loaded_image_device_path),
+            options,
         }
     }
 
@@ -41,6 +45,11 @@ impl RootContext {
             .as_deref()
             .ok_or_else(|| anyhow!("no loaded image path"))
     }
+
+    /// Access the global Sprout options.
+    pub fn options(&self) -> &SproutOptions {
+        &self.options
+    }
 }
 
 /// A context of Sprout. This is passed around different parts of Sprout and represents

src/generators/bls.rs

@@ -33,6 +33,13 @@ fn default_bls_path() -> String {
     BLS_TEMPLATE_PATH.to_string()
 }
 
+// TODO(azenla): remove this once variable substitution is implemented.
+/// This function is used to remove the `tuned_initrd` variable from entry values.
+/// Fedora uses tuned which adds an initrd that shouldn't be used.
+fn quirk_initrd_remove_tuned(input: String) -> String {
+    input.replace("$tuned_initrd", "").trim().to_string()
+}
+
 /// Generates entries from the BLS entries directory using the specified `bls` configuration and
 /// `context`. The BLS conversion is best-effort and will ignore any unsupported entries.
 pub fn generate(
@@ -108,10 +115,18 @@ pub fn generate(
 
         // Produce a new sprout context for the entry with the extracted values.
         let mut context = context.fork();
-        context.set("title", entry.title().unwrap_or(name));
-        context.set("chainload", entry.chainload_path().unwrap_or_default());
-        context.set("options", entry.options().unwrap_or_default());
-        context.set("initrd", entry.initrd_path().unwrap_or_default());
+
+        let title = entry.title().unwrap_or(name);
+        let chainload = entry.chainload_path().unwrap_or_default();
+        let options = entry.options().unwrap_or_default();
+
+        // Put the initrd through a quirk modifier to support Fedora.
+        let initrd = quirk_initrd_remove_tuned(entry.initrd_path().unwrap_or_default());
+
+        context.set("title", title);
+        context.set("chainload", chainload);
+        context.set("options", options);
+        context.set("initrd", initrd);
 
         // Add the entry to the list with a frozen context.
         entries.push((context.freeze(), bls.entry.clone()));

src/main.rs

@@ -2,8 +2,10 @@
 #![feature(uefi_std)]
 
 use crate::context::{RootContext, SproutContext};
+use crate::options::SproutOptions;
+use crate::options::parser::OptionsRepresentable;
 use crate::phases::phase;
-use anyhow::{Context, Result, bail};
+use anyhow::{Context, Result};
 use log::info;
 use std::collections::BTreeMap;
 use std::ops::Deref;
@@ -37,6 +39,9 @@ pub mod phases;
 /// setup: Code that initializes the UEFI environment for Sprout.
 pub mod setup;
 
+/// options: Parse the options of the Sprout executable.
+pub mod options;
+
 /// utils: Utility functions that are used by other parts of Sprout.
 pub mod utils;
 
@@ -47,10 +52,13 @@ fn main() -> Result<()> {
     // Initialize the basic UEFI environment.
     setup::init()?;
 
+    // Parse the options to the sprout executable.
+    let options = SproutOptions::parse().context("unable to parse options")?;
+
     // Load the configuration of sprout.
     // At this point, the configuration has been validated and the specified
     // version is checked to ensure compatibility.
-    let config = config::loader::load()?;
+    let config = config::loader::load(&options)?;
 
     // Load the root context.
     // This is done in a block to ensure the release of the LoadedImageDevicePath protocol.
@@ -64,7 +72,7 @@ fn main() -> Result<()> {
             "loaded image path: {}",
             loaded_image_path.to_string(DisplayOnly(false), AllowShortcuts(false))?
         );
-        RootContext::new(loaded_image_path)
+        RootContext::new(loaded_image_path, options)
     };
 
     // Insert the configuration actions into the root context.
@@ -144,9 +152,14 @@ fn main() -> Result<()> {
     // Execute the late phase.
     phase(context.clone(), &config.phases.late).context("unable to execute late phase")?;
 
-    // Pick the first entry from the list of final entries until a boot menu is implemented.
-    let Some((context, entry)) = final_entries.first() else {
-        bail!("no entries found");
+    // Use the boot option if possible, otherwise pick the first entry.
+    let (context, entry) = if let Some(ref boot) = context.root().options().boot {
+        final_entries
+            .iter()
+            .find(|(_context, entry)| &entry.title == boot)
+            .context(format!("unable to find entry: {boot}"))?
+    } else {
+        final_entries.first().context("no entries found")?
     };
 
     // Execute all the actions for the selected entry.

src/options.rs

@@ -0,0 +1,84 @@
+use crate::options::parser::{OptionDescription, OptionForm, OptionsRepresentable};
+use anyhow::{Context, Result, bail};
+use std::collections::BTreeMap;
+
+/// The Sprout options parser.
+pub mod parser;
+
+/// Default configuration file path.
+const DEFAULT_CONFIG_PATH: &str = "\\sprout.toml";
+
+/// The parsed options of sprout.
+#[derive(Debug)]
+pub struct SproutOptions {
+    /// Path to a configuration file to load.
+    pub config: String,
+    /// Entry to boot without showing the boot menu.
+    pub boot: Option<String>,
+}
+
+/// The default Sprout options.
+impl Default for SproutOptions {
+    fn default() -> Self {
+        Self {
+            config: DEFAULT_CONFIG_PATH.to_string(),
+            boot: None,
+        }
+    }
+}
+
+/// The options parser mechanism for Sprout.
+impl OptionsRepresentable for SproutOptions {
+    /// Produce the [SproutOptions] structure.
+    type Output = Self;
+
+    /// All the Sprout options that are defined.
+    fn options() -> &'static [(&'static str, OptionDescription<'static>)] {
+        &[
+            (
+                "config",
+                OptionDescription {
+                    description: "Path to Sprout configuration file",
+                    form: OptionForm::Value,
+                },
+            ),
+            (
+                "boot",
+                OptionDescription {
+                    description: "Entry to boot, bypassing the menu",
+                    form: OptionForm::Value,
+                },
+            ),
+            (
+                "help",
+                OptionDescription {
+                    description: "Display Sprout Help",
+                    form: OptionForm::Help,
+                },
+            ),
+        ]
+    }
+
+    /// Produces [SproutOptions] from the parsed raw `options` map.
+    fn produce(options: BTreeMap<String, Option<String>>) -> Result<Self> {
+        // Use the default value of sprout options and have the raw options be parsed into it.
+        let mut result = Self::default();
+
+        for (key, value) in options {
+            match key.as_str() {
+                "config" => {
+                    // The configuration file to load.
+                    result.config = value.context("--config option requires a value")?;
+                }
+
+                "boot" => {
+                    // The entry to boot.
+                    result.boot = Some(value.context("--boot option requires a value")?);
+                }
+
+                _ => bail!("unknown option: --{key}"),
+            }
+        }
+        Ok(result)
+    }
+}

src/options/parser.rs

@@ -0,0 +1,150 @@
+use anyhow::{Context, Result, bail};
+use std::collections::BTreeMap;
+
+/// The type of option. This disambiguates different behavior
+/// of how options are handled.
+#[derive(Debug, Clone, Ord, PartialOrd, Eq, PartialEq)]
+pub enum OptionForm {
+    /// A flag, like --verbose.
+    Flag,
+    /// A value, in the form --abc 123 or --abc=123.
+    Value,
+    /// Help flag, like --help.
+    Help,
+}
+
+/// The description of an option, used in the options parser
+/// to make decisions about how to progress.
+#[derive(Debug, Clone)]
+pub struct OptionDescription<'a> {
+    /// The description of the option.
+    pub description: &'a str,
+    /// The type of option to parse as.
+    pub form: OptionForm,
+}
+
+/// Represents a type that can be parsed from command line arguments.
+/// This is a super minimal options parser mechanism just for Sprout.
+pub trait OptionsRepresentable {
+    /// The output type that parsing will produce.
+    type Output;
+
+    /// The configured options for this type. This should describe all the options
+    /// that are valid to produce the type. The left hand side is the name of the option,
+    /// and the right hand side is the description.
+    fn options() -> &'static [(&'static str, OptionDescription<'static>)];
+
+    /// Produces the type by taking the `options` and processing it into the output.
+    fn produce(options: BTreeMap<String, Option<String>>) -> Result<Self::Output>;
+
+    /// For minimalism, we don't want a full argument parser. Instead, we use
+    /// a simple --xyz = xyz: None and --abc 123 = abc: Some("123") format.
+    /// We also support --abc=123 = abc: Some("123") format.
+    fn parse_raw() -> Result<BTreeMap<String, Option<String>>> {
+        // Access the configured options for this type.
+        let configured: BTreeMap<_, _> = BTreeMap::from_iter(Self::options().to_vec());
+
+        // Collect all the arguments to Sprout.
+        // Skip the first argument which is the path to our executable.
+        let args = std::env::args().skip(1).collect::<Vec<_>>();
+
+        // Represent options as key-value pairs.
+        let mut options = BTreeMap::new();
+
+        // Iterators makes this way easier.
+        let mut iterator = args.into_iter().peekable();
+
+        loop {
+            // Consume the next option, if any.
+            let Some(option) = iterator.next() else {
+                break;
+            };
+
+            // If the doesn't start with --, that is invalid.
+            if !option.starts_with("--") {
+                bail!("invalid option: {option}");
+            }
+
+            // Strip the -- prefix off.
+            let mut option = option["--".len()..].trim().to_string();
+
+            // An optional value.
+            let mut value = None;
+
+            // Check if the option is of the form --abc=123
+            if option.contains("=") {
+                let Some((part_key, part_value)) = option.split_once("=") else {
+                    bail!("invalid option: {option}");
+                };
+
+                let part_key = part_key.to_string();
+                let part_value = part_value.to_string();
+                option = part_key;
+                value = Some(part_value);
+            }
+
+            // Error on empty option names.
+            if option.is_empty() {
+                bail!("invalid empty option");
+            }
+
+            // Find the description of the configured option, if any.
+            let Some(description) = configured.get(option.as_str()) else {
+                bail!("invalid option: --{option}");
+            };
+
+            // Check if the option requires a value and error if none was provided.
+            if description.form == OptionForm::Value && value.is_none() {
+                // Check for the next value.
+                let maybe_next = iterator.peek();
+
+                // If the next value isn't another option, set the value to the next value.
+                // Otherwise, it is an empty string.
+                value = if let Some(next) = maybe_next
+                    && !next.starts_with("--")
+                {
+                    iterator.next()
+                } else {
+                    None
+                };
+            }
+
+            // If the option form does not support a value and there is a value, error.
+            if description.form != OptionForm::Value && value.is_some() {
+                bail!("option --{} does not take a value", option);
+            }
+
+            // Handle the --help flag case.
+            if description.form == OptionForm::Help {
+                // Generic configured options output.
+                println!("Configured Options:");
+                for (name, description) in &configured {
+                    println!(
+                        "  --{}{}: {}",
+                        name,
+                        if description.form == OptionForm::Value {
+                            " <value>"
+                        } else {
+                            ""
+                        },
+                        description.description
+                    );
+                }
+                // Exit because the help has been displayed.
+                std::process::exit(1);
+            }
+
+            // Insert the option and the value into the map.
+            options.insert(option, value);
+        }
+        Ok(options)
+    }
+
+    /// Parses the program arguments as a [Self::Output], calling [Self::parse_raw] and [Self::produce].
+    fn parse() -> Result<Self::Output> {
+        // Parse the program arguments into a raw map.
+        let options = Self::parse_raw().context("unable to parse options")?;
+        // Produce the options from the map.
+        Self::produce(options)
+    }
+}