AxionOS

Getting Started

AxionOS is based on the Android Open Source Project (AOSP) with extra performance and some customization features.
This guide will walk you through downloading the source code, setting up the build environment, and configuring your device tree.

Download the Source

First, initialize the repo:

repo init -u https://github.com/AxionAOSP/android.git -b lineage-23.0 --git-lfs

Then sync the source code:

repo sync

Set up Build Environment

Follow the LineageOS build guide to install the required packages.
Then configure the build environment:

. build/envsetup.sh

---

Device Tree Setup

AxionOS builds on top of LineageOS, so you should start from a LineageOS-compatible device tree.
Add this to your device makefile:

TARGET_DISABLE_EPPE := true
$(call inherit-product, vendor/lineage/config/common_full_phone.mk)

Optional flags:

• Enable blur effects

  TARGET_ENABLE_BLUR := true

• Enable ViPER4AndroidFX

  TARGET_INCLUDE_VIPERFX := true

  (Disabled by default. Requires proper drivers and libraries.)
  See the ViPER4AndroidFX ReadMe.

• Enable debugging

  add in product overrides or set using console: adb shell setprop persist.sys.ax_debug_enabled 1 
  persist.sys.ax_debug_enabled=1

  (Disabled by default. Meant for debugging purposes - bootloop, aidl/hardware dependency by sepolicy failure, etc)

---

AxionOS Device Properties

AxionOS supports custom properties for "About phone" and system optimization.
Set these in your device tree:

# Camera information (multiple sensors supported)
AXION_CAMERA_REAR_INFO := 50,48
AXION_CAMERA_FRONT_INFO := 42

# Maintainer name (underscores become spaces in the UI)
AXION_MAINTAINER := rmp_22

# Processor name (underscores become spaces)
AXION_PROCESSOR := Snapdragon_CPU_1

These are automatically exported to system properties at build time.

---

Firmware Configuration

AxionOS added properties and flags to tune the OS for device experience. You can enable or disable them in your device makefile:

# Charging
BYPASS_CHARGE_SUPPORTED ?= false

# CPU governor support
PERF_GOV_SUPPORTED := false
PERF_DEFAULT_GOV := schedutil
PERF_ANIM_OVERRIDE := false

# GPU
GPU_FREQS_PATH := /sys/devices/platform/28000000.mali/available_frequencies
GPU_MIN_FREQ_PATH := /sys/devices/platform/28000000.mali/hint_min_freq

# High Brightness Mode (HBM)
HBM_SUPPORTED := false
HBM_NODE := /sys/class/backlight/panel0-backlight/hbm_mode

# Flashlight strength
TORCH_STR_SUPPORTED := false

# doze fix
# for devices with doze/sensor related issues 
TARGET_NEEDS_DOZE_FIX := false

# [experimental] userspace simple lmk trial version 
# of https://github.com/kerneltoast/android_kernel_google_gs201/blob/16.0.0-sultan/drivers/android/simple_lmk.c ©kerneltoast
# Targets devices with prebuilt kernels or uslmk support across kernels
TARGET_USES_USLMK := false

# do not enable TARGET_IS_LOW_RAM if your device ram is greater than 4gb
# else OOM will most likely occur on operations where applications and camera can fill heap limit
# e.g uploading video/media on apps with camera preview
# this is a mitigation targets legacy devices 4gb below
# Using quicken is a trade-off: here we trade clean pages for dirty pages,
# extra cpu and battery. That's because the quicken files will be jit-ed in all
# the processes that load of shared apk and the code cache is not shared.
# Some notable apps that will be affected by this are gms and chrome.
TARGET_IS_LOW_RAM ?= false

• Bypass Charging: Allows charging while keeping the battery percentage fixed.
  If supported, you must also add a SELinux rule for the input_suspend node.

• Governor Support: Allows switching CPU governors if supported by your kernel.

• High Brightness Mode (HBM): Enable if your panel supports a high brightness toggle.

• Flashlight strength: Enable if torch supports strength changes.

ScrollOptimizer

ScrollOptimizer is an AxionOS feature that optimizes frame pacing and buffer handling during UI scroll and fling operations. It improves touch responsiveness and reduces rendering latency, ported from Linaro’s proprietary implementation.

Properties

# Enable or disable ScrollOptimizer globally
persist.sys.perf.scroll_opt = true

# Heavy app handling mode
# 0 - Disable heavy app classification
# 1 - Enable dynamic detection (based on frame duration and buffer load)
# 2 - Treat all apps as heavy for performance
persist.sys.perf.scroll_opt.heavy_app = 2

Source: ScrollOptimizer.java

SEPolicy Adjustments

Some devices need SELinux adjustments to allow AxionOS performance tuning.

Performance mode

• If your device uses standard labels, add rules like this to your device tree:

genfscon proc /sys/vm/dirty_writeback_centisecs     u:object_r:proc_dirty:s0
genfscon proc /sys/vm/vfs_cache_pressure            u:object_r:proc_drop_caches:s0
genfscon proc /sys/vm/dirty_ratio                   u:object_r:proc_dirty:s0
genfscon proc /sys/kernel/sched_migration_cost_ns   u:object_r:proc_sched:s0

GPU boost

• To allow boost framework to access your device gpu nodes, add genfs context for your node and label it as sysfs_gpu

genfscon sysfs /devices/platform/1c500000.mali/available_frequencies                   u:object_r:sysfs_gpu:s0
genfscon sysfs /devices/platform/1c500000.mali/hint_min_freq                   u:object_r:sysfs_gpu:s0

SEPolicy conflicts

• If your device uses different OEM labels (common on MediaTek or Qualcomm), add allow rules instead of relabeling.

allow init proc_vm_dirty:file rw_file_perms;
allow init proc_dirty_ratio:file rw_file_perms;

---

Prebuilt LineageOS Apps

You can choose whether to include LineageOS prebuilt apps.
Default is disabled.

TARGET_INCLUDES_LOS_PREBUILTS := true/false

---

Building AxionOS

Generate Private Keys

Run once before building:

gk -s

Choose Device

To configure your device build:

axion <device_codename> [variant]

Variants:

• gms core → Core Google Mobile Services (default if no variant given)
• gms pico → Minimal Google apps
• va → Vanilla (no GMS)

Example:

axion panther gms pico

Sync Updates

To update your source after the first sync:

axionSync

Build the ROM

Finally, compile:

ax -br -j<count>

Replace <count> with the number of CPU threads you want to use (e.g. ax -j16).

---

Credits

AxionOS is based on the work of the Android Open Source Project (AOSP) and LineageOS.
Thanks to all contributors for their hard work.