Technical review — 2026-10-13: This is a historical Nexus 5 / Android Lollipop tutorial with an obsolete device and toolchain. Its LRX22C binaries correspond to Android 5.0.1 / AOSP android-5.0.1_r1. The source, binary, and flashing requirements below are tied to that combination. An Android 16 Cuttlefish example is added separately; do not mix it with the old phone firmware.

Following my previous article, Using Android Studio to View Android Lollipop Source Code, we know that simply reading code has its limits—understanding can remain superficial and easily forgotten. In contrast, code you’ve personally written or modified tends to leave a much deeper impression, and the process becomes easier to grasp during the implementation phase. While studying the source code, being able to modify it, run it on a phone, and see the results firsthand significantly boosts both learning efficiency and enthusiasm. This article explains how to compile the Android Lollipop source code yourself and run it on a Nexus 5.

Why compile your own firmware instead of using Google’s factory images?
The goal here is a userdebug build suitable for platform debugging. User builds restrict facilities such as ADB root. Userdebug enables more debugging operations, but does not make every partition freely writable under all conditions.

This guide assumes a consistent Lollipop source tree and a Nexus 5. See the historical AOSP environment guide and source download instructions. Android 5.x uses OpenJDK 7 on Linux. Keep its old OS and dependencies in a dedicated historical build environment rather than using it as the setup for a current workstation.

AOSP means Android Open Source Project. It includes the platform and open-source apps, but not the proprietary Google Mobile Services (GMS) suite. Hardware binaries, GMS licensing, and Android compatibility are separate matters. Meeting the CDD and passing CTS establishes compatibility; it does not automatically grant GMS. For the requirements, see the Android compatibility overview.