How to build your own custom Android ROM

Some of the key options of Android is that it’s open supply. The supply code for the whole running gadget, together with the kernel, UI, libraries and key apps, is to be had totally free. Which means somebody (with the proper technical talents) can build Android from supply and flash it onto a suitable software. This pliability has allowed more than a few teams, a few business and a few hobbyist, to increase choice distributions of Android. Those are often referred to as “custom ROMs” on the other hand a greater identify can be “custom firmware.”

On account that all of the important construction blocks are to be had, perhaps you’ve gotten questioned how onerous it’s to build your own custom ROM, your own personalised model of Android! It’s certainly imaginable, learn on to in finding out extra.


Ahead of we dive into the murky global of establishing custom variations of Android, we’d like to pause and determine the enormity of the duty in advance, at the same time as maintaining our expectancies in test. If in case you have completely no coding revel in, zero revel in with the use of the command line (on Linux or macOS), or no concept what’s a “Makefile” then this isn’t for you.

Android is a whole running device. It’s complicated and accommodates various subsystems. Developing an running gadget as complicated and helpful as Android didn’t occur over night time. Which means any customization that you would like to carry out goes to have to get started small. To create an alternate Android distribution that may be considerably other will take many, many hours of exhausting paintings and determination.

Having stated that. In case you are conversant in writing code, should you do realize a bit of approximately Makefiles and compilers then making your own model of Android is usually a worthwhile revel in!

Must haves

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Theoretically it will be imaginable to build a custom Android firmware for any computing tool able to operating a up to date running gadget. On the other hand to make lifestyles simple we will be able to restrict ourselves to construction Android to units that have make stronger “out of the field”, specifically Nexus units. For my demo build I used a Nexus 5X.

To build Android you’re going to want get entry to to (and familiarity with) and Linux system or a Mac. In each instances you’ll be the use of the terminal so much and you wish to have to be assured with shell instructions. I did my first build the use of a Linux digital system, on the other hand it wouldn’t acknowledge the Nexus 5X while in bootloader mode, so I used to be not able to flash the brand new firmware at the tool. So then I switched to a Mac and it labored with out too many issues.

You are going to want 130GB of disk area and most certainly round 8GB of RAM. I attempted construction Android with simply 4GB of RAM and I bumped into a lot of issues. I additionally bumped into equivalent issues of 8GB of RAM, then again the use of a few tips (see later) I used to be in a position to create a a success build.

Be informed endurance. Construction Android isn’t fast. To synchronize the supply repository with my native system took virtually 24 hours! Additionally, a whole blank build will take a couple of hours to whole. Even after creating a minor amendment chances are you’ll want to wait 10 to 20 mins for a build. All of it will depend on your hardware, then again don’t be expecting to have your new model of Android up and operating in only a few moments.

The Android Open Supply Undertaking model of Android does now not come with any Google products and services. So such things as Google Play, YouTube, Gmail and Chrome shall be lacking. There are methods to flash the ones “gapps” onto your own custom firmware, however I will be able to depart you to learn how to do this. Trace: Seek for “set up gapps”.

The place to get started

The fundamental procedure is that this. Obtain and build Android from the Android Open Supply Challenge, then regulate the supply code to get your own custom model. Easy!

Google supplies a few very good documentation approximately construction AOSP ^( You wish to have to learn it after which re-learn it after which learn it once more. Don’t bounce any steps and don’t think you understand what it’s going to say subsequent and read over portions.

I gained’t repeat verbatim what’s within the build directions right here, then again the overall steps are:

  • Arrange a build setting – together with putting in the appropriate construction equipment, the Java Construction Package, and getting all of the paths and directories proper.
  • Take hold of the supply – that is performed the use of the “Repo” software and git.
  • Download proprietary binaries – one of the most drivers are handiest launched in binary shape.
  • Make a selection a objective – the use of the “lunch” software.
  • Get started the build – the use of “make” and Jack.
  • Flash the build onto your tool – the use of adb and fastboot.

Guidelines and tips for the build procedure

That every one sounds simple, however there are a couple of gotchas alongside the best way. Listed here are a few notes I made all through the method that chances are you’ll in finding helpful:

Arrange a build setting – Ubuntu 14.04 is the beneficial build setting for Linux customers and OS X 10.11 for Mac customers. You wish to have to set up OpenJDK 8 on Linux and Oracles JDK 8 on OS X. On OS X you additionally want Macports put in along side Xcode an the Xcode command line equipment. I used OS X 10.12 which brought about somewhat drawback with the serve as syscalls being deprecated within the 10.12 OS X SDK. The paintings round is right here:

Grasp the supply – This is a straightforward step, then again it takes a very long time. For me it took over 24 hours. Any such massive obtain best occurs as soon as, additional syncing with the primary supply tree can be incremental.

Download proprietary binaries – The binary drivers will have to be unpacked in your running listing.

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Select a objective – For the Nexus 5X use aosp_bullhead-consumer

Get started the build – You get started the build the use of make. GNU make can care for parallel duties with a -jN argument, and it’s not unusual to use quite a few duties N that’s among 1 and 2 occasions the selection of hardware threads at the pc getting used for the build. Then again, for those who in finding your system struggles throughout the build procedure then check out one thing like “make -j2”.

Should you get build mistakes which appear similar to reminiscence, particularly concerning the Jack server and reminiscence then do those two issues:

  • export ANDROID_JACK_VM_ARGS=”-Xmx4g -Dfile.encoding=UTF-8 -XX:+TieredCompilation”
  • amendment the jack.server.max-carrier in $HOME/.jack-server/ to 1

In case you amendment any of the Jack server configuration stuff (together with surroundings or changing the ANDROID_JACK_VM_ARGS variable) then you wish to have to kill the Jack server and run the make once more. Use ./prebuilts/sdk/equipment/jack-admin kill-server to prevent the Jack server.

When you get any communications mistakes similar to the Jack server then simply get started the build once more, that generally fixes it.

Flash the build onto your tool – You are going to in finding adb and fastboot in ./out/host/darwin-x86/bin/ or ./out/host/darwin-x86/bin/ for OS X or Linux respectively.

Flash it

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Upon getting a a success build and you have got flashed it onto your tool the use of “fastboot flashall -w” then reboot your tool. What you are going to see is a vanilla model of AOSP. There aren’t any Google products and services, no Play Retailer and just a few center apps. That is the naked bones of Android.

On the other hand, congratulations are so as. You will have controlled to build Android from its supply code and flash it on to a tool. That may be no imply feat.

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Now that you’ve got Android up and operating, you’ll be able to get started to customise it and make your own expert ROM. That is in reality the place issues get onerous. You’re approximately to tinker with a guts of the Android running gadget and the issue is that Android is massive. My running listing is like one hundred twenty+GB of knowledge. That may be the supply code, the pix, the compiled binaries, the equipment, the whole thing. That may be a large number of stuff.

So, get started easy. Listed here are two easy customizations so they can get you going, get started at the trail to being an Android firmware hacker!

Customise the messaging app

A quite simple customization is to amendment one of the pre-constructed apps. Should you have been to boost a whole choice Android distribution then editing or changing one of the center apps can be a given. On this case we’re simply going to tweak it, on the other hand the rules stay the similar for extra complicated adjustments and revisions.

The center apps are discovered within the listing ./programs/apps/  and we have an interest within the Messaging app in ./programs/apps/Messaging/. Drill down thru src/com/android/messaging/ and edit You’ll be able to edit it with your favourite GUI editor or if you wish to have to keep at the command line then use vi or nano. is the access aspect for the Messaging app. To stay issues easy what we’re going to do is upload a Toast for you to be displayed while the app is first began. Close to the highest of the document beneath the lengthy listing of import statements upload this line:

import android.widget.Toast;

Now search for the onCreate() serve as. Against the top of the serve as, ahead of the general name to Hint.endSection(); upload the next two strains:

Toast myToast = Toast.makeText(getApplicationContext(), "Welcome!", Toast.LENGTH_LONG);

Store the document and get started some other build the use of the make command. As soon as the build has completed, flash it onto your software and reboot. Get started the Messaging app and search for the “Welcome!” toast. Clearly this can be a easy amendment, then again the prospective is there to adjust any of the default apps, in no matter what approach you please.

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Extra customization

Any self-respecting custom Android distribution will have to come with a few details about the ROM itself. To try this we will be able to regulate the integrated Settings app and upload a few knowledge to the Approximately Telephone segment. To try this, edit the document device_info_settings.xml from ./programs/apps/Settings/res/xml/ and upload the next two sections on the backside of the document ahead of ultimate </PreferenceScreen> tag:

<!-- ROM identify -->
<Choice android:key="rom_name"
android:name="ROM identify"
android:abstract="Whizz Bang Pop ROM"/> <!-- ROM build model -->
<Choice android:key="rom_number"
android:name="ROM build quantity"

Shop the document after which rebuild and re-flash the firmware on your software. When you reboot pass to Settings->Approximately Telephone and scroll to the ground:

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The above alteration is slightly of hack as in point of fact the strings will have to be outlined in strings.xml for English and for others languages. For those who plan to do any critical AOSP construction you wish to have to do issues proper!


The two changes I’ve made are very fundamental and there’s quite a bit extra that may be performed together with pre-putting in different apps, including ringtones & wallpapers, and tweaking the kernel. Then again I am hoping this has given you a style of what’s imaginable or no less than given you a concept approximately how to build AOSP and tinker with the innards of Android!