LineageOS Development

This skill covers LineageOS custom ROM development - from syncing sources to building and contributing.

Getting Started

Initialize Source

bash

mkdir ~/lineage && cd ~/lineage

# Install repo (if needed)
mkdir -p ~/.bin
curl https://storage.googleapis.com/git-repo-downloads/repo > ~/.bin/repo
chmod a+x ~/.bin/repo
export PATH="$HOME/.bin:$PATH"

# Init LineageOS 21 (Android 14)
repo init -u https://github.com/LineageOS/android.git -b lineage-21.0 --git-lfs

# Sync
repo sync -c -j$(nproc) --force-sync --no-tags --no-clone-bundle

Build Commands

bash

# Setup environment
source build/envsetup.sh

# Setup device (syncs device repos too)
breakfast <device>

# Build flashable ZIP
brunch <device>
# Or separately:
breakfast <device>
mka bacon

# Output: out/target/product/<device>/lineage-21.0-*-UNOFFICIAL-<device>.zip

Essential Commands

Command	Purpose
`breakfast <device>`	Setup device + sync dependencies
`brunch <device>`	breakfast + full build
`mka bacon`	Build flashable ZIP
`mka bootimage`	Build kernel only
`mka systemimage`	Build system only
`repopick <change>`	Cherry-pick from Gerrit

Device Trees

Required Files

code

device/<vendor>/<device>/
├── lineage_<device>.mk      # Product makefile
├── lineage.dependencies     # Repo dependencies
├── vendorsetup.sh           # Add to lunch
├── BoardConfig.mk           # Hardware config
├── device.mk                # Packages and configs
└── extract-files.sh         # Vendor blob extraction

lineage_<device>.mk

makefile

# Inherit device
$(call inherit-product, device/vendor/device/device.mk)

# Inherit LineageOS common
$(call inherit-product, vendor/lineage/config/common_full_phone.mk)

PRODUCT_NAME := lineage_device
PRODUCT_DEVICE := device
PRODUCT_BRAND := Vendor
PRODUCT_MODEL := Device Name
PRODUCT_MANUFACTURER := Vendor

lineage.dependencies

json

[
  {
    "repository": "android_kernel_vendor_device",
    "target_path": "kernel/vendor/device"
  },
  {
    "repository": "android_device_vendor_device-common",
    "target_path": "device/vendor/device-common"
  },
  {
    "repository": "proprietary_vendor_device",
    "target_path": "vendor/device"
  }
]

repopick - Cherry-picking from Gerrit

bash

# Single change
repopick 12345

# Multiple changes
repopick 12345 12346 12347

# By topic
repopick -t feature-topic

# With dependencies
repopick -Q 12345

# Force overwrite local changes
repopick -f 12345

# Show what would be picked
repopick -n 12345

Find Change Numbers

•Go to https://review.lineageos.org
•Search for changes
•Change number is in the URL or displayed

Vendor Blobs

Extract from Device

bash

cd device/vendor/device
./extract-files.sh

Extract from OTA/Factory Image

bash

./extract-files.sh ~/Downloads/ota.zip

proprietary-files.txt Format

txt

# Audio HAL
vendor/lib64/hw/audio.primary.platform.so
vendor/etc/audio_policy_configuration.xml

# With destination path
vendor/lib64/lib.so:vendor/lib64/libfoo.so

# From another device
vendor/lib64/lib.so|other_device

LineageOS Features

Trust Interface

Security dashboard showing device integrity:

makefile

# device.mk
PRODUCT_PACKAGES += \
    LineageTrust

LiveDisplay

Hardware-accelerated display tuning:

makefile

PRODUCT_PACKAGES += \
    lineage.livedisplay@2.0-service-sdm

Styles / Themes

System theming support:

makefile

PRODUCT_PACKAGES += \
    ThemePicker

Key Directories

Path	Purpose
`vendor/lineage/`	LineageOS additions
`lineage-sdk/`	LineageOS SDK
`device/<vendor>/<device>/`	Device tree
`kernel/<vendor>/<device>/`	Kernel source
`vendor/<vendor>/`	Proprietary blobs

Contributing

Setup Gerrit Access

bash

git config --global review.review.lineageos.org.username <username>

Submit Change

bash

# Create branch
repo start my-feature .

# Make changes
git add -A
git commit -m "subsystem: Short description

Detailed explanation.

Change-Id: <auto-generated>"

# Push for review
git push ssh://<username>@review.lineageos.org:29418/<project> HEAD:refs/for/<branch>

Commit Message Format

code

subsystem: Short description

Longer explanation wrapped at 72 characters.
Explain why, not what.

Change-Id: I1234567890abcdef...

Common Issues

Breakfast Fails - Missing Repos

bash

# Re-sync device tree
repo sync device/vendor/device kernel/vendor/device vendor/device

Build Fails - SELinux

bash

# Find denials
adb shell dmesg | grep "avc: denied"

# Generate policy (on host)
adb shell dmesg | audit2allow -p out/target/product/<device>/root/sepolicy

Missing Blobs

Check logcat for:

code

E linker: cannot find symbol...
E ServiceManager: Could not find service...

Add missing files to proprietary-files.txt and re-extract.

Quick Reference

bash

# Full workflow
source build/envsetup.sh
breakfast cheeseburger
brunch cheeseburger

# Just kernel
mka bootimage

# Cherry-pick fix
repopick 12345

# Sync everything
repo sync -c -j$(nproc)

# Sync one project
repo sync packages/apps/Settings

# Clean build
m clean && brunch <device>