[Xperia Z4/Z3+ Original Android Development] Olivier:
MultiROM is a one-of-a-kind multi-boot mod. It can boot any Android ROM as well as other systems like Ubuntu Touch, once they are ported to that device. Besides booting from device's internal memory, MultiROM can boot from USB drive connected to the device via OTG cable. The main part of MultiROM is a boot manager, which appears every time your device starts and lets you choose ROM to boot. You can see how it looks on the left image below and in gallery. ROMs are installed and managed via modified TWRP recovery. You can use standard ZIP files to install secondary Android ROMs and MultiROM even has its own installer system, which can be used to ship other Linux-based systems.

Features:

* Multiboot any number of Android ROMs

* Restore nandroid backup as secondary ROM

* Boot from USB drive attached via OTG cable

You can also watch a video which shows it in action.​

WARNING

It is dangerous. This whole thing is basically one giant hack - none of these systems are made with multibooting in mind. It is no longer messing with data partition or boot sector, but it is possible that something goes wrong and you will have to flash factory images again. Make backups. Always.​

IMPORTANT

I'm not responsible for anything, you do all this on your own risk.

Once you have flashed and set up MultiROM, don't flash another boot.img using fastboot or normally. Always go to TheMultiROM Menu (3 bars in the top right corner) to flash ROMs/kernels or other mods.

If you want to uninstall MultiROM, just flash the MultiROM uninstaller.

I am not certainly sure about the compatibility with stock Roms, I still need to test this yet.

Your device must not be encrypted.

When booting another ROM, you'll notice that in some cases, you can enter the recovery of the boot.img of the ROM. Please don't use it, flash everything using MultiROM TWRP.

INSTALLATION

Make sure you are on a Rom compatible with one of these kernels and flash it or use the non-kexec workaround. (See important Notices)

Reboot into MultiROM TWRP and flash the MultiROM installer

That's it. You can now go to TheMultiROM Menu (3 bars in the top right corner) to start flashing other ROMs.

Adding ROMs

Go to recovery, select TheMultiROM Menu (3 bars in the top right corner) -> Add ROM. Select the ROM's zip file and confirm.​

Using USB drive

During installation, recovery lets you select install location. Plug in the USB drive, wait a while and press "refresh" so that it shows partitions on the USB drive. You just select the location (extX, NTFS and FAT32 partitions are supported) and proceed with the installation.

If you wanna use other than default FAT32 partition, just format it in PC. If you don't know how/don't know where to find out how, you probably should not try installing MultiROM.

If you are installing to NTFS or FAT32 partition, recovery asks you to set image size for all the partitions - this cannot be easilly changed afterward, so choose carefully. FAT32 is limited to maximum of 4095MB per image - it is limitation of the filesystem, I can do nothing about that.

Installation to USB drives takes a bit longer, because the flash drive is (usually) slower and it needs to create the images, so installation of Ubuntu to 4Gb image on my pretty fast USB drive takes about 20 minutes.

Enumerating USB drive can take a while in MultiROM menu, so when you press the "USB" button in MultiROM, wait a while (max. 30-45s) until it searches the USB drive. It does it by itself, no need to press something, just wait.​

Updating/changing ROMs

1. Primary ROM (Internal)

Flash ROM's ZIP file as usual, do factory reset if needed (it won't erase secondary ROMs)

Go to TheMultiROM Menu (3 bars in the top right corner) in recovery and do Inject curr. boot sector.

2. Secondary Android ROMs

If you want to change the ROM, delete it and add new one. To update ROM, follow these steps:

Go to TheMultiROM Menu (3 bars in the top right corner) -> List ROMs and select the ROM you want to update.

Select "Flash ZIP" and flash ROM's ZIP file.

SOURCEs

MultiROM - https://github.com/XperiaMultiROM/multirom/ (branch master)

Modified TWRP - https://github.com/multirom-htc/Team-Win-Recovery-Project (branch android-6.0)

Kernel w/ kexec-hardboot patch - https://github.com/olivieer/android_kernel_sony_msm8994 (branch 32.1.A.0.xxx)​

FAQs can be found here.

CREDITs

Tasssadar

Myself5

nkk71

Garcia98

XDA:DevDB Information

MultiROM for Sony Xperia Z4/Z3+, Tool/Utility for the Sony Xperia Z4

Contributors

Olivier

Version Information

Status: Beta

Created 2016-05-20

Last Updated 2016-05-20