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Examples used throughout this guide: ROM source → Clover Project (Android 16) Target device → Xiaomi Redmi Note 13 Pro 5G (garnet) · Snapdragon 7s Gen 2

Why Custom ROM?
Pros & Cons
Custom ROM vs OEM ROM
Custom ROM in 2026 — Still Worth It?
Pre-Requirements
Device Trees
ROM Source
Basic Bringup & Sync Source
Lunch & Build
Upload, Flash & Test

Why Custom ROM?

A Custom ROM is a fully customized version of the Android operating system, built independently from any device manufacturer's official firmware. Rooted in the open-source nature of Android (AOSP), custom ROMs give developers and power users complete control over their mobile experience — from the kernel level all the way to the UI.

Custom ROM projects follow the tradition of legendary builds like CyanogenMod, LineageOS, OmniROM, and AOKP — each targeting newer Android versions with a shared philosophy:

AOSP purity — no unnecessary bloat on top of Android's foundation
Stability first — each release tested before being tagged stable
Meaningful features — only what genuinely improves the experience
Long-term support — keeping devices alive beyond manufacturer EOL

For the Redmi Note 13 Pro 5G, which ships with Xiaomi's HyperOS (known for heavy telemetry, ads, and slow security patches), Clover offers a compelling and transparent alternative.

Why does this matter in 2026? OEM support cycles are shrinking. Xiaomi typically offers 3–4 years of OS updates. Custom ROMs can extend a device's life indefinitely as long as the community maintains it.

Pros & Cons

Advantages of Custom ROM

Benefit	Description
No Bloatware	Clean AOSP base — zero pre-installed ads or manufacturer apps
Privacy	No OEM telemetry, fully auditable open-source code
Performance	Lighter system footprint, faster UI response
Root Access	Easy Magisk / KernelSU integration
Long-Term Support	Community may maintain device years past OEM EOL
Customization	Deep system-level theming, tweaks, and mods
Security Patches	Community often delivers patches faster than OEM
Google-Free Option	Compatible with microG for de-Googled experience
Open Source	Full source on GitHub — see exactly what runs on your phone
Learning	Best hands-on education for Android internals

Disadvantages of Custom ROM

Drawback	Description
Warranty Void	Bootloader unlock voids manufacturer warranty on most devices
Banking Apps	May require extra steps to pass Play Integrity / SafetyNet
Camera Quality	OEM camera AI stack often missing — photo quality degrades
VoLTE / VoWiFi	May break or require manual carrier configuration
DRM Widevine	Usually drops from L1 to L3 — Netflix/Prime lose HD playback
Stability Risk	You're a beta tester — bugs are expected
Brick Risk	Incorrect flashing can hard-brick the device
Technical Skill	Setup requires Linux knowledge, patience, and research
No Guaranteed OTA	Updates depend on maintainer availability

Custom ROM vs OEM ROM

Category	Clover Project (Custom)	HyperOS (OEM)
Software Updates	Community-driven, faster patches	Slow, Xiaomi-schedule dependent
Bloatware	None — clean AOSP	Heavy — built-in ads & Xiaomi apps
Privacy / Telemetry	Fully transparent, auditable	Extensive data collection
Camera Performance	Basic AOSP camera	Full Xiaomi AI camera stack
Banking Apps	Works with Play Integrity fix	Works out of the box
Stability	Varies by maintainer	Generally stable
Customization	Deep system-level control	Surface-level themes only
Performance	Snappier (less overhead)	Good but heavier
Battery Life	Better (fewer background services)	Decent with battery saver
VoLTE / VoWiFi	May need manual config	Native support
Root Access	Easy (Magisk / KernelSU)	Not officially supported
Widevine L1	Drops to L3	L1 preserved
Long-Term Support	Community extends beyond EOL	3–4 years, then abandoned
Source Code	Fully open on GitHub	Closed proprietary firmware

Custom ROM in 2026 — Still Worth It?

The custom ROM scene in 2026 has matured but also grown more challenging. Here's the honest breakdown:

Yes — For Developers

If your goal is to understand Android deeply, contribute to open source, or build for a specific use case, custom ROM development is absolutely worthwhile. The learning experience — kernel porting, HAL integration, SELinux policies, AIDL/HIDL — is irreplaceable.

Maybe — For Power Users

If you want a clean, fast, private daily driver and can tolerate camera and banking workarounds — yes. Research the specific device maintainer's track record before committing.

No — For General Users

If you rely on mobile banking, OEM camera features, or simply want things to work without maintenance — stick with the stock ROM. Custom ROMs require technical tolerance and ongoing attention.

2026 Verdict: The tooling ecosystem is healthier than ever (Docker build environments, Android Common Kernel, lineageos-build-scripts). However, Qualcomm's proprietary blobs, Google's Play Integrity API, and increasingly complex camera stacks make shipping a fully competitive daily driver harder than the CyanogenMod era. Clover's bet on AOSP purity over feature bloat is the right philosophy for 2026.

Pre-Requirements

Hardware Requirements

Component	Minimum	Recommended
CPU	4 cores	12–16 cores
RAM	16 GB	32–64 GB
Storage	300 GB SSD	500 GB+ NVMe SSD
OS	Ubuntu	Ubuntu 22.04 / 24.04
Internet	50 Mbps	100+ Mbps
Build Time	—	1–3 hrs (first), ~30 min (incremental)

System Setup

# Install all build dependencies (Ubuntu 22.04 / 24.04)
sudo apt update && sudo apt install -y \
  bc bison build-essential ccache curl flex g++-multilib gcc-multilib \
  git git-lfs gnupg gperf imagemagick lib32ncurses5-dev lib32readline-dev \
  lib32z1-dev liblz4-tool libncurses5 libncurses5-dev libsdl1.2-dev \
  libssl-dev libxml2 libxml2-utils lzop pngcrush rsync schedtool \
  squashfs-tools xsltproc zip zlib1g-dev python3 python3-pip \
  openjdk-21-jdk

# Install the repo tool
mkdir -p ~/bin
curl https://storage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
chmod a+x ~/bin/repo
echo 'export PATH=~/bin:$PATH' >> ~/.bashrc && source ~/.bashrc

# Configure git (required by repo)
git config --global user.email "you@example.com"
git config --global user.name "Your Name"

# Setup ccache for significantly faster rebuilds
export USE_CCACHE=1
export CCACHE_EXEC=$(which ccache)
ccache -M 50G
echo 'export USE_CCACHE=1' >> ~/.bashrc

Knowledge Prerequisites

Before starting, you should be comfortable with:

Linux CLI — bash, permissions, scripting, make, grep, pipes
Git & Repo — manifests, local manifests, cherry-picks, branch management
Android Architecture — kernel, HAL, Binder IPC, system services, framework
Build System — reading and writing Android.bp (Soong) and Android.mk files
SELinux — understanding type enforcement, file contexts, and neverallow rules

Device Prerequisites

Bootloader Unlock (Required)

Device Trees

Device trees are the bridge between generic AOSP source and your specific hardware. For example garnet, you need three repositories working together:

Tree Types

General for all device

Tree	Path	Purpose
Device Tree	`device/xiaomi/garnet`	Init scripts, SELinux, overlays, build configs, prop flags
Kernel	`kernel/xiaomi/sm7435`	Linux kernel source for Snapdragon 7s Gen 2
Vendor	`vendor/xiaomi/garnet`	Proprietary blobs — camera HAL, modem firmware, Qualcomm DSP
Hardware Xiaomi	`hardware/xiaomi`	Xiaomi-specific HIDL/AIDL hardware interface implementations

Other trees

Tree	Path	Purpose
Device Common	`device/xiaomi/sm7435-common`	Shared SoC-level configs across all SM7435 devices
Kernel Modules	`kernel/xiaomi/sm7435-modules`	Out-of-tree kernel drivers (Wi-Fi, audio, sensors)
Kernel Device Trees	`kernel/xiaomi/sm7435-devicetrees`	DTS/DTSI files for SM7435 board and device variants
Vendor Common	`vendor/xiaomi/sm7435-common`	Shared vendor blobs across all SM7435 devices
Hardware Dolby	`hardware/dolby`	Dolby Atmos audio HAL and sound configuration
MIUI Camera App	`vendor/xiaomi/miuicamera-garnet`	Pre-built MIUI/Leica camera APK and supporting libraries
MIUI Camera Config	`device/xiaomi/miuicamera-garnet`	Camera integration configs, overlays and permissions

Note: The tree paths, names, and structure below are specific to Xiaomi Redmi Note 13 Pro 5G (garnet) used as an example in this guide. For other brands and devices, the paths, codenames, SoC identifiers, and repository names will vary accordingly — e.g. device/oneplus/kebab, kernel/samsung/exynos9820, vendor/google/pixel etc.

Device Tree File Structure

device/xiaomi/garnet/
├── Android.bp                  # Build system entry point
├── AndroidProducts.mk          # Product definition (lunch targets)
├── BoardConfig.mk              # Hardware-level build flags ← critical
├── device.mk                   # Main Makefile (packages, props, features)
├── clover_garnet.mk            # ROM-specific product config
├── audio/                      # Audio policy XMLs
├── configs/
│   ├── media_codecs.xml
│   ├── media_profiles.xml
│   ├── manifest.xml            # VINTF hardware manifest
│   └── thermal-engine.conf
├── display/                    # Display AIDL configs
├── init/
│   ├── init.garnet.rc          # Device init scripts ← critical
│   └── init.target.rc
├── overlay/                    # Resource overlays (strings, configs)
├── rootdir/etc/
│   ├── fstab.qcom              # Partition mount table ← critical
│   └── ueventd.rc
├── sepolicy/                   # SELinux policies
│   ├── vendor/
│   └── private/
└── proprietary-files.txt       # List of blobs to extract from stock

Key `BoardConfig.mk` Settings for garnet

# Platform
BOARD_VENDOR                    := xiaomi
TARGET_BOARD_PLATFORM           := pineapple
TARGET_ARCH                     := arm64
TARGET_ARCH_VARIANT             := armv8-2a-dotprod
TARGET_CPU_ABI                  := arm64-v8a
TARGET_CPU_VARIANT              := cortex-a78

# Kernel
BOARD_KERNEL_BASE               := 0x00000000
BOARD_KERNEL_PAGESIZE           := 4096
TARGET_KERNEL_CONFIG            := garnet_defconfig
TARGET_KERNEL_SOURCE            := kernel/xiaomi/sm7435
BOARD_KERNEL_IMAGE_NAME         := Image

# Dynamic Partitions (garnet uses super partition)
BOARD_SUPER_PARTITION_SIZE                := 9653190656
BOARD_SUPER_PARTITION_GROUPS              := qti_dynamic_partitions
BOARD_QTI_DYNAMIC_PARTITIONS_SIZE         := 9649094656
BOARD_QTI_DYNAMIC_PARTITIONS_PARTITION_LIST := system system_ext product vendor odm

# VINTF
DEVICE_MANIFEST_FILE            := device/xiaomi/garnet/configs/manifest.xml
DEVICE_MATRIX_FILE              := device/xiaomi/garnet/configs/compatibility_matrix.xml

Extracting Vendor Blobs

# Method 1: Extract live from a running stock device via ADB
cd device/xiaomi/garnet
./extract-files.sh

# Method 2: Extract from a stock ROM dump
# Download fastboot ROM → unpack with payload-dumper-go
payload-dumper-go payload.bin
simg2img system.img system.raw
mkdir -p /mnt/system && sudo mount -o loop system.raw /mnt/system

# Method 3: Use a community blob archive
git clone  \
    vendor/xiaomi/garnet

Blob version must match your target stock ROM version exactly. Mismatched blobs cause bootloops, camera crashes, and modem failures.

ROM Source (example - clover project)

The Clover Project source is hosted on GitHub and uses Google's repo manifest system to track hundreds of repositories that together form the complete Android build system.

Basic Bringup & Sync Source

A full sync is approximately 150–300 GB. Use a wired connection and plan for 2–5 hours.

Initialize & Sync

sync

# Create your build directory
mkdir -p ~/android/clover-16 && cd ~/android/clover-16

# Initialize the repo manifest
repo init \
  -u https://github.com/CloverProject/android.git \
  -b android-16.0 \
  --depth=1 \
  --git-lfs

# Sync all sources — adjust -j to your thread count
repo sync -c -j16 --force-sync --no-clone-bundle --no-tags

If a repo fails mid-sync, simply run repo sync again — it resumes from where it stopped.

Bringup

Clone all the required repositories using Git.

Step 1 — Adapt the device tree

# If porting from a LineageOS base tree, rename product targets
sed -i 's/lineage_garnet/clover_garnet/g' device/xiaomi/garnet/*.mk
sed -i 's/PRODUCT_NAME := lineage/PRODUCT_NAME := clover/g' device/xiaomi/garnet/*.mk

Step 2 — Verify partition layout

Run fastboot getvar all on the device and compare super partition sizes against your BoardConfig.mk. Garnet uses Dynamic Partitions — this must be correct or fastboot flashing will fail.

Step 3 — Confirm vendor blobs are in place

ls vendor/xiaomi/garnet/proprietary/
# Expected: lib/  lib64/  bin/  etc/  firmware/

Step 4 — Initial SELinux handling

For first bringup, add this to your BoardConfig.mk to bypass SELinux neverallow failures:

SELINUX_IGNORE_NEVERALLOWS := true

Fix SELinux policies properly before any public release.

Lunch & Build

Initialize Build Environment

build

cd ~/android/clover-16

# Source the build environment
source build/envsetup.sh

# Select your build target
# Format: lunch {product_name}-{buildtype}
# Buildtypes: user (release) | userdebug (root+debug) | eng (full debug)
lunch clover_garnet-userdebug

Expected output:

============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=16
TARGET_PRODUCT=clover_garnet
TARGET_BUILD_VARIANT=userdebug
TARGET_BUILD_TYPE=release
TARGET_ARCH=arm64
HOST_ARCH=x86_64
============================================

Build the ROM

# Full build — use all CPU threads
m -j$(nproc) 

# Or use the ROM's own build script
mka clover -j$(nproc --all)

Build Outputs

out/target/product/garnet/
├── clover_garnet-ota-YYYYMMDD-garnet.zip  ← Your flashable ROM package
├── boot.img                                ← Kernel + ramdisk
├── recovery.img                            ← Recovery image
├── vendor_boot.img                         ← Vendor ramdisk (GKI)
├── dtbo.img                                ← Device Tree Blob Overlay
├── system.img                              ← System partition
├── vendor.img                              ← Vendor partition
└── super.img                               ← Combined dynamic partitions

Common Build Errors

Error	Likely Cause	Fix
`ninja: 'out/.../obj/...' missing`	Missing blob or broken `Android.bp`	Check `proprietary-files.txt` and vendor tree
`ld.lld: undefined symbol`	Library not listed in vendor or device tree	Add missing `.so` to `Android.bp` or device tree
`No rule to make target`	Module name mismatch	Check `LOCAL_PACKAGE_NAME` in `Android.mk`
`FAILED: out/.../sepolicy`	SELinux neverallow violation	Fix policy or use `SELINUX_IGNORE_NEVERALLOWS`
`error: unsatisfied requirement`	VINTF manifest mismatch	Update `manifest.xml` or `compatibility_matrix.xml`

Upload, Flash & Test

Flashing via Custom Recovery (TWRP / OrangeFox)

# 1. Boot to bootloader
adb reboot bootloader

# 2. Flash recovery
fastboot flash recovery recovery.img
fastboot reboot recovery

# 3. In recovery: Wipe → Format Data
# 4. Push ROM ZIP and flash
adb push out/target/product/garnet/clover_garnet-ota-*.zip /sdcard/
# Then in TWRP: Install → select ZIP → Swipe to Flash

Flashing via Fastboot (partition-by-partition)

adb reboot bootloader

# Flash A/B-agnostic partitions
fastboot flash boot boot.img
fastboot flash vendor_boot vendor_boot.img
fastboot flash dtbo dtbo.img

# Switch to fastbootd for dynamic partitions
fastboot -w reboot fastboot

# Flash dynamic partitions
fastboot flash system system.img
fastboot flash vendor vendor.img
fastboot flash product product.img
fastboot flash system_ext system_ext.img

fastboot reboot

Debugging a Bootloop

# Capture logcat during bootloop
adb logcat | grep -E "(FATAL|ERROR|crash|tombstone)" | tee crash.log

# Check battery stats for wakelock drain
adb shell dumpsys batterystats | grep "Wake lock"

# Check SELinux denials
adb shell dmesg | grep -i "avc: denied"

# Check init failures
adb logcat -b all | grep -i "failed\|error\|crash" | head -100

Device Info

Attribute	Value
Device Name	Xiaomi Redmi Note 13 Pro 5G
Codename	`garnet`
SoC	Qualcomm Snapdragon 7s Gen 2 (SM7435)
Architecture	ARM64 (armv8-2a-dotprod)
RAM	8 / 12 GB LPDDR4X
Storage	128 / 256 GB UFS 2.2
Display	6.67" AMOLED, 120Hz, 2712×1220
Camera (Main)	200 MP, OIS
Battery	5100 mAh, 67W fast charge
Android Version	Android 16 (Clover Project)
Partition Scheme	Dynamic Partitions (Super)
Kernel	Linux 5.15.x GKI

Disclaimer

This guide is for educational and development purposes only. Flashing custom software carries inherent risks including data loss, bootloops, and hardware damage. The authors are not responsible for any damage to your device. Always backup your data before modifying your device. Proceed at your own risk.

Flash responsibly. Contribute openly. Keep devices alive.

Android Custom ROM Development Guide

Table of Contents

Why Custom ROM?

Pros & Cons

Advantages of Custom ROM

Disadvantages of Custom ROM

Custom ROM vs OEM ROM

Custom ROM in 2026 — Still Worth It?

Yes — For Developers

Maybe — For Power Users

No — For General Users

Pre-Requirements

Hardware Requirements

System Setup

Knowledge Prerequisites

Device Prerequisites

Device Trees

Tree Types

Device Tree File Structure

Key `BoardConfig.mk` Settings for garnet

Extracting Vendor Blobs

ROM Source (example - clover project)

Basic Bringup & Sync Source

Initialize & Sync

Bringup

Lunch & Build

Initialize Build Environment

Build the ROM

Build Outputs

Common Build Errors

Upload, Flash & Test

Flashing via Custom Recovery (TWRP / OrangeFox)

Flashing via Fastboot (partition-by-partition)

Debugging a Bootloop

Device Info

Disclaimer

Table of Contents

Why Custom ROM?

Pros & Cons

Advantages of Custom ROM

Disadvantages of Custom ROM

Custom ROM vs OEM ROM

Custom ROM in 2026 — Still Worth It?

Yes — For Developers

Maybe — For Power Users

No — For General Users

Pre-Requirements

Hardware Requirements

System Setup

Knowledge Prerequisites

Device Prerequisites

Device Trees

Tree Types

Device Tree File Structure

Key BoardConfig.mk Settings for garnet

Extracting Vendor Blobs

ROM Source (example - clover project)

Basic Bringup & Sync Source

Initialize & Sync

Bringup

Lunch & Build

Initialize Build Environment

Build the ROM

Build Outputs

Common Build Errors

Upload, Flash & Test

Flashing via Custom Recovery (TWRP / OrangeFox)

Flashing via Fastboot (partition-by-partition)

Debugging a Bootloop

Device Info

Disclaimer

Key `BoardConfig.mk` Settings for garnet