Multi-Booting the Nexus 7 Tablet

Anyone who knows me well enough knows I love mobile devices. Phones, tablets and other shiny glowing gadgets are almost an addiction for me. I've talked about my addiction in other articles and columns, and Kyle Rankin even made fun of me once in a Point/Counterpoint column because my household has a bunch of iOS devices in it. Well, I was fortunate enough to add an Android device to the mix recently—a Nexus 7 tablet. I actually won this device at the Southern California Linux Expo as part of the Rackspace Break/Fix Contest, but that's a different story.

If you've not seen a Nexus 7, it's a nice little device. Like all "Nexus"-branded Android devices, it's a "reference" device for Google's base Android implementation, so it's got a well-supported set of hardware. I'm not trying to make this article sound like a full-fledged review of the device, but here's a few tech specs in case you're not familiar with it:

  • 7" screen with 1280x800 resolution.

  • 7.81" x 4.72" x 0.41" (198.5mm x 120mm x 10.45mm).

  • 16 or 32GB of Flash storage (mine is the 16GB model).

  • 1GB of RAM.

  • NVIDIA Tegra 3 Quad-Core Processor.

  • Wi-Fi, Bluetooth and optional 3G radios.

  • Android 4.2 Jelly Bean.

The Nexus line of Android devices makes up the reference implementation for Android, so that tends to be the series of device that sees the fastest movement in terms of new builds of the OS, and in unique OS derivatives like CyanogenMod. Right about the time I received the Nexus 7, Canonical released the developer beta of Ubuntu Touch, which targeted the Nexus 7 as its deployment platform.

Because I can't leave nice things well enough alone, I decided to start trying alternate OS ROMs on my shiny new Nexus 7. Ordinarily, each new OS would require you to reflash the device, losing all your configuration, apps and saved data. However, I found a neat hack called MultiROM that lets you sideload multiple ROMs on your device. How does it work? Well, let's walk through the installation.

Prep for MultiROM Installation

First, and I can't stress this enough, back up your device. I really, really mean it. Back up your device. You're messing around with lots of low-level stuff when you're installing MultiROM, so you'll want to have copies of your data. Also, one of the first steps is to wipe the device and return it to an "out-of-the-box" configuration, so you'll want your stuff safe.

Second, grab copies of the "stock" Nexus 7 ROMs as they shipped from the factory. You will want these in the event something goes wrong, or if you decide you don't like this MultiROM hackery and want to roll your device back to a stock configuration.

Third, check the links in the Resources section of this article for up-to-date documentation on MultiROM. It's possible for things to change between this writing and press time, so follow any instructions you see there. Those instructions will supersede anything I type here, as this kind of hack can be a rapidly moving target. Also, do your own homework—lots of great YouTube videos describe this process, and a video sometimes can be worth several thousand words.

Notice: please make sure you follow these three steps, then follow the MultiROM documentation exactly. I'm not responsible if your tablet gets bricked or turns itself into SkyNet and goes on a rampage against humanity. Though I have to say, if that happened, it'd be kind of neat, in a geeky sort of way.

Unlocking Your Bootloader

Your device should be on the latest available factory ROM supported by MultiROM before you begin the installation. At the time of this writing, on my Nexus 7 (Wi-Fi-only) model, that was 4.2.2. The Nexus 7 comes from the factory with a "locked" bootloader. The first thing you've got to do is unlock the bootloader before you can proceed.

To unlock the bootloader, you need the Android SDK tools installed on your computer (see the Resources section for a download link). Specifically, you'll need the fastboot and adb tools for this, so make sure they're on your system and in your shell's PATH environment variable.

Next, hook up your tablet to your computer via the USB-to-MicroUSB cable, and then run:


adb reboot bootloader

Your tablet then will reboot, and you'll be in the Android bootloader. Once you're in the bootloader, run the following command:


sudo fastboot oem unlock

Next, you'll be prompted to confirm the command and accept that all data on your device will be erased. The tablet then will reboot, winding up in the setup wizard where you'll be prompted for all your setup information as if it were fresh out of the box once more.

Installing MultiROM

Now that your bootloader is unlocked, you can proceed to the trickiest part of this process—installing MultiROM. Grab a copy of it from the XDA-Developers MultiROM thread (the link is in the Resources section of this article; currently the filename is multirom_v10_n7-signed.zip). You'll also need to get the modified TWRP install file (TWRP_multirom_n7_20130404.img) and a patched kernel (kernel_kexec_422.zip). Rename the TWRP install file to recovery.img, then hook your tablet back up to your computer, and place these files in the root of its filesystem (keep the .zip files zipped—don't unzip them).

Next, from your computer's command line, you'll need to run the adb utility from the Android SDK again, but this time, with the proper argument to get the system to boot to "recovery" mode:


adb reboot recovery

This will bring the device to "Clockwork Recovery" mode. From the Recovery menu on the device, choose "Install zip from sdcard", followed by "choose zip from sdcard", then specify the MultiROM zip file you moved to the root of your tablet's filesystem earlier. When it's done flashing, select "reboot system now", and your Nexus 7 will reboot.

Once the device boots normally, issue the following command from your computer to get the system back in the bootloader:


adb reboot bootloader

The device will reboot in bootloader mode. Select the fastboot option on the screen, then type the following on your computer:


sudo fastboot flash recovery recovery.img

That'll flash the modified recovery image that MultiROM requires to your tablet. Next, just tell the tablet to reboot by issuing the following command to it:


sudo fastboot reboot

Your Nexus 7 now is ready to install alternate ROMs.

______________________

Bill Childers is the Virtual Editor for Linux Journal. No one really knows what that means.

Comments

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Nexus is a line of Android

mobilepundits's picture

Nexus is a line of Android devices make a reference implementation for Android. Your process of installing multi ROM in devices looks more complicated..

The nexus is one of the best

mobilepundits's picture

The nexus is one of the best line in Android devices make up the reference implementation in Android. Installing multiple ROM on device looks more complicated....

Welcome to admin

App Store's picture

Nice post and Your website are very cool. I am lucky to be able to come into your weblog and I will bookmark this web page in order that I could come back another time. Keep up the good work android apps

Welcome to admin

App Store's picture

Your article has proven helpful to me . android market is very informative and you really are obviously very educated in this region. You possess opened up my eyes to varying views on this topic with interesting and solid content. Thanks

Great

Essay writing's picture

Thanks for writing such a good article, I stumbled onto your blog and read a few post. I like your style of writing..

comment

How to's picture

Thank you. I finally understand how to multi-boot in nexus 7 tablet

I also love mobile device,

Shah Alam's picture

I also love mobile device, Nexus 7 looks well and it's feature are also like to me. Thanks for the review about this device!! http://www.appsta.com/windows-phone

surface prep equipment

surface prep equipment's picture

Thanks for some other informative website. Where else may I am getting that type of information written in such a perfect manner? I’ve a project that I am simply now operating on, and I have been on the glance out for such info.
Thank you
surface prep equipment
Masud Hossen
Website: http://www. moorearentals.com/

Hey guys, I want to tell you

Charles Murray's picture

Hey guys, I want to tell you something for an example. I got a Samsung mobile phone and I got all the essentials features in it so why should I go for iphone?

nexus 7 2

khurram jamil's picture

The Nexus 7 2 can connect to a TV via HDMI, using a microUSB extension. Although Google did not mention that the HDMI output, it can also handle DVI and VGA with the appropriate adapters, but we have not been able to test it for ourselves. If ever there was a demand for it, we may make additional tests until we have a unit on hand. Let us know in the comments. The tablet has the same capacity “USB to HDMI” as that found on the Nexus 4 smartphone.

ClockworkMod Recovery

N.Olsen's picture

Unless I'm gravely mistaken, clockworkmod recovery (CWM) isn't standard even on the Nexus7.

You can probably flash signed zips from the stock recovery though, at least with an unlocked bootloader. (can't remember)

will they beat ipad?,i will

rentalmobil's picture

will they beat ipad?,i will buy this awesome nexus rental mobil

Complicated

craigdesign's picture

It looks complicated but seems fun to install multi-ROM.

MultiROM for the N7 (2013)

Anonymous's picture

Help bring "MultiROM" to more devices: http://www.indiegogo.com/projects/multirom-for-nexus-7-2013

Webinar
One Click, Universal Protection: Implementing Centralized Security Policies on Linux Systems

As Linux continues to play an ever increasing role in corporate data centers and institutions, ensuring the integrity and protection of these systems must be a priority. With 60% of the world's websites and an increasing share of organization's mission-critical workloads running on Linux, failing to stop malware and other advanced threats on Linux can increasingly impact an organization's reputation and bottom line.

Learn More

Sponsored by Bit9

Webinar
Linux Backup and Recovery Webinar

Most companies incorporate backup procedures for critical data, which can be restored quickly if a loss occurs. However, fewer companies are prepared for catastrophic system failures, in which they lose all data, the entire operating system, applications, settings, patches and more, reducing their system(s) to “bare metal.” After all, before data can be restored to a system, there must be a system to restore it to.

In this one hour webinar, learn how to enhance your existing backup strategies for better disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible bare-metal recovery solution for UNIX and Linux systems.

Learn More

Sponsored by Storix