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-23.2 --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

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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 AxionFx

  TARGET_INCLUDE_AXFX := true

• 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)

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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.

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Firmware Configuration

Axion Flags

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

# safely disable libperfmgr without breaking boot (set to true)
TARGET_DISABLES_LIBPERF ?= false

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

# doze flags
# for devices with doze/sensor related issues 
TARGET_NEEDS_DOZE_FIX := false
# doze gestures
TARGET_DOZE_TAP_PULSE_SUPPORTED ?= false
TARGET_DOZE_DOUBLE_TAP_PULSE_SUPPORTED ?= false
TARGET_DOZE_PICKUP_PULSE_SUPPORTED ?= false
TARGET_DOZE_SIDE_FPS_PULSE_SUPPORTED ?= 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.

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

Ax Kernel Manager

Ax Kernel Manager configures CPU frequencies, CPU governors, and GPU clocks using sysfs nodes defined in ax_kernel_manager.xml.

If your SoC is not already present in device/axion/common/prebuilts/ax_kernel_manager_$(AXION_SOC).xml, you can create and ship your own configuration in your device tree.

Shipping in Device Tree

Copy your XML to $(TARGET_COPY_OUT_VENDOR)/etc/ax_kernel_manager.xml (or $(TARGET_COPY_OUT_SYSTEM_EXT)):

PRODUCT_COPY_FILES += \
    $(LOCAL_PATH)/configs/kernel/ax_kernel_manager.xml:$(TARGET_COPY_OUT_VENDOR)/etc/ax_kernel_manager.xml

The loader checks /odm/etc, /vendor/etc, /system_ext/etc, and /system/etc in order.

Configuration (ax_kernel_manager.xml)

<?xml version="1.0" encoding="utf-8"?>
<kernel-manager>
    <!-- CPU clusters -->
    <cpu
        id="little"
        group="Little Cluster"
        minId="axion_min_freq"
        maxId="axion_max_freq"
        governorId="little_cpu_governor"
        node="/sys/devices/system/cpu/cpufreq/policy0" />

    <cpu
        id="big"
        group="Big Cluster"
        minId="axion_min_freq_big"
        maxId="axion_max_freq_big"
        governorId="big_cpu_governor"
        node="/sys/devices/system/cpu/cpufreq/policy4" />

    <!-- GPU (Qualcomm Adreno kgsl or ARM Mali devfreq) -->
    <gpu
        node="/sys/class/kgsl/kgsl-3d0/devfreq"
        currentNode="/sys/class/kgsl/kgsl-3d0/gpuclk"
        usageNode="/sys/class/kgsl/kgsl-3d0/gpu_busy_percentage"
        frequencyMultiplier="1"
        values="255000000,500000000,835000000,1000000000" />
</kernel-manager>

• <cpu> attributes:

  • node: Policy directory (e.g. /sys/devices/system/cpu/cpufreq/policy0). Automatically resolves child nodes: scaling_min_freq, scaling_max_freq, scaling_cur_freq, scaling_available_frequencies, scaling_governor, and scaling_available_governors. You can override any node individually (minNode, maxNode, curFreqPath, availablePath, governorNode, governorAvailablePath).
  • id & group: Identifier and UI display name.
  • cpuIds: Core range for metrics (e.g. 0-3).
  • minId / maxId / governorId: Settings keys used to persist frequencies and governors (e.g. axion_min_freq, axion_max_freq, little_cpu_governor).

• <gpu> attributes:

  • node: Base devfreq path. Automatically resolves min_freq and max_freq (overridable with minNode and maxNode).
  • currentNode: Active clock path (gpuclk on Adreno, cur_freq on Mali).
  • usageNode: GPU load or utilization path (gpu_busy_percentage on Adreno, utilization on Mali).
  • values: Comma-separated list of supported frequencies (or set availablePath).
  • frequencyMultiplier: Set 1 for Hz (Adreno) or 1000 for kHz (Mali).

Device Permissions & SEPolicy

Because system_server applies frequency and governor values at runtime, sysfs nodes must be writable:

1. init.<device>.rc:

   on post-fs-data
       chown system system /sys/devices/system/cpu/cpufreq/policy0/scaling_governor
       chown system system /sys/devices/system/cpu/cpufreq/policy0/scaling_min_freq
       chown system system /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
       chmod 0660 /sys/devices/system/cpu/cpufreq/policy0/scaling_governor
       chmod 0660 /sys/devices/system/cpu/cpufreq/policy0/scaling_min_freq
       chmod 0660 /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
   

2. SEPolicy: Grant system_server read/write access to CPU and GPU sysfs nodes (e.g. sysfs_devices_system_cpu, vendor_sysfs_kgsl, vendor_sysfs_devfreq).

If no XML is provided, Ax Kernel Manager automatically falls back to discovering CPU policies under /sys/devices/system/cpu/cpufreq/ and GPU nodes under /sys/class/kgsl/ or /sys/class/devfreq/.

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

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;

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Prebuilt LineageOS Apps

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

TARGET_INCLUDES_LOS_PREBUILTS := true/false

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Building AxionOS

Generate Private Keys

Run once before building:

gk -s

Choose Device

To configure your device build:

axion <device_codename> [user|userdebug|eng] [gms|pico|core|full|va]

Build type defaults to userdebug if omitted.

GMS variants:

• gms / full → Full Google Mobile Services
• pico → Minimal Google Mobile Services
• core → Core Google Mobile Services
• va / vanilla → Non-GMS build

Optional GMS package flags:

# Telecom-related Google apps/services bundle.
# Defaults: false for pico, true for core/gms.
TARGET_INCLUDE_GOOGLE_TELECOMM := true/false

# Google setup/partner setup bundle.
# Defaults: false for pico/core, true for gms.
TARGET_INCLUDE_PARTNER_SETUP := true/false

These flags are overridable from your device/product makefile. For example, use TARGET_INCLUDE_GOOGLE_TELECOMM := true to include the telecom bundle on pico, or TARGET_INCLUDE_PARTNER_SETUP := false to exclude setup packages from core/gms.

If no GMS variant is specified, axion defaults to a non-GMS build.

The build flavor shown in the output zip/version is one of:

• GMS
• PICO
• CORE
• VANILLA

Example:

axion panther gms
axion panther pico
axion panther core
axion panther va

Adding flags without adding flags to tree

axion has scripts for writing flags without needing to add flags to tree

writeFlag TARGET_INCLUDE_GOOGLE_TELECOMM false
removeFlag TARGET_INCLUDE_GOOGLE_TELECOMM
clearFlags -- removes all flags written via writeFlag

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).

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Credits

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