Like any PC, you can now multi boot / dual boot Nexus 7 tablet, thanks to MultiROM v2 for Nexus 7. This way you can have multiple OSes installed on your device. You can install any Android ROM or Ubuntu on Nexus 7 tablet. The process is risky but it should work just fine if you follow the steps carefully. This will allow you to boot into multiple ROMs at any time you want. Here is all you need to know, followed by step by step guide on how to do it:
How to Flash MultiROM on Nexus 7 with Modified TWRP Recovery
Before you Begin:
- Backup all your data as you may lose it during the process.
- Make sure that USB Debugging is enabled on your device. If not, you can enable it from Settings > Developer Options and enable “USB Debugging” from there.
WARNING: Continue at your own risk, we will not be responsible for any harm to your device by following the steps.
Step 1: Download required files:
- MultiROM: multirom_v2_n7-signed.zip
- Modified TWRP Recovery: TWRP_multirom_n7_20121202.img
- Fastboot: For Windows, Mac or Linux (zip file)
Step 2: Copy the MultiROM zip file on your device.
Step 3: Disconnect your device from PC and boot it into recovery mode.
Step 4: In recovery mode, flash the MultiROM zip file that you copied to your device in step 2.
Step 5: Rename the TWRP_multirom_n7_20121202.img to recovery.img.
Step 6: Execute following command to flash the modified recovery:
fastboot flash recovery recovery.img
This will flash the modified TWRP Recovery on Nexus 7. You will now see additional options for multi boot in recovery mode.
New Options in Modified TWRP Recovery for Nexus 7
Following new options will be added:
- Add ROM – add ROM to boot
- List ROMs – list installed ROMs and manage them
- Inject boot.img file – When you download for example kernel, which is distrubuted as whole boot.img (eg. franco kernel), you have to use this option on it, otherwise you would lose MultiROM.
- Inject curr. boot sector – Use this option if MultiROM does not show up on boot, for example after kernel installation.
- Settings – well, settings.
- Rename, delete – I believe these are obvious
- Flash ZIP (only Android ROMs) – flash ZIP to the ROM, for example gapps
- Add/replace boot.img – replaces boot.img used by this ROM, this is more like developer option.
The only settings so far is to set ROM which is booted as default.
Boot into Recovery mode and flash the ROM.
How to Flash Multiple ROMs on Nexus 7 with MultiROM
To Flash Android ROM:
Step 1: Download the ROM and copy the downloaded zip file to Nexus 7.
Step 2: Start Nexus 7 in recovery mode.
Step 3: In recovery mode, select Advanced -> MultiROM -> Add ROM option.
Step 4: Now Select the ROM zip file and confirm.
Step 5: Reboot your device.
Clean installation of stock 4.2 after first boot (with dalvik cache generated and connected to google account) takes 676MB of space.
Repeat the process to install another ROM.
How to Install Ubuntu on Nexus 7 Dual Boot / Multi Boot
Step 1: Download Ubuntu image from here. Recommended download: rootfs.img for Nexus 7 8GB.
Step 2: Copy the downloaded Ubuntu image in the memory of Nexus 7 or to USB flash drive.
Step 3: Start your device in recovery mode.
Step 4: In Recovery mode, select Advanced -> MultiROM -> Add ROM option.
Step 5: Now select "Ubuntu" as ROM type. Then select the Ubuntu’s image and confirm.
Clean installation of Ubuntu is 1.5GB big, but it needs 2-3GB for the installation process itself (for the first boot).
For more information, head over to official XDA thread.