Boot Multiple Roms on Your Sony Xperia M with MultiROM Xperia
MultiROM is probably a name that many on XDA will recognize, especially if you’re an owner of one of the officially supported devices, such as the Nexus 7, for which MultiROM was originally developed by XDA Recognized Developer Tasssadar. As you may have guessed from the name, MultiROM is a tool that enables one to boot multiple different ROMs on a supported device, without going through all the hoops such as wiping a ROM or performing backups.
Well, it seems like another device has discovered the magic of MultiROM, with the Sony Xperia M receiving an unofficial port of the tool called MultiROM Xperia, courtesy of XDA Senior Member alvinhochun. As of right now, MultiROM Xperia is in its alpha phase and is up for testing, but its installer is still not ready, meaning one must install this by flashing its boot image through fastboot.
In action, MultiROM Xperia can boot multiple ROMs installed on either your micro SD card or a USB storage device connected to your phone via an OTG cable. Additionally, if you have a kernel with a kexec-hardboot patch, you can even boot ROMs with kernels different from one another
MultiROM Xperia is compatible with both the single SIM and dual SIM variants of the Xperia M, and will only work when the device’s bootloader is unlocked and running the 15.1.C.2.8 build of Android 4.1.2. So if you’re interested in multiboot solution to your Xperia M, check out the original thread for more information.