[LG Optimus 2x] spyrosk:
Here is the guide to get Real Dual boot on both BLs.

Please read carefully because this may mess up your phone if you don't know what you are doing.

Oh!! I forgot, this phone is unbrickable, so give it a try.​

Installation Instructions

Extract the downloaded package with WinRAR or similar to any folder.

Copy ROM1, ROM2 and the DualBoot-Control.zip to external SD.

Go to the folder DualBoot-Partition-resizer and run flash.bat (or flash.sh for linux) follow on-screen instructions select BootLoader and wait until NVFlash process finishes and the screen goes black.

Disconnect the USB cable, put the battery back and just power on the phone it will enter into recovery automatically. (It takes about 40 secs to enter recovery 1st time after NVFlash)

Install

DualBoot-Control.zip

and select Enable Dual Boot option. The phone will reboot (if supported by recovery) and enter in recovery again (if not select reboot recovery from recovery).

Make a full wipe just in case to avoid boot-loops and format /system because it may not be formatted by ROM’s updater-script (mounts and storage --> format /system)

Now flash ROM1 (or restore a nandroid backup of ROM1) and without rebooting install

DualBoot-Control.zip

, select ROM1 update and reboot when it finishes.

When the phone completely boots, you will find an app called SystemChanger, launch it and click Switch ROM, it will ask you for root rights, click yes, the phone will reboot quickly, press and hold Pwr button + vol down when the screen goes black to enter recovery, if the phone doesn't go to recovery, remove the battery, plug it again and enter recovery.

Format /system (the 2nd system now), because it may not be formatted by ROM’s updater-script.

Now flash ROM2 and without rebooting install

DualBoot-Control.zip

, select ROM2 update and reboot when it finishes. (Attention: do not restore a backup of ROM2 because it will wipe data files of ROM1)

And that is all, if you want to switch to ROM1, as before, run SystemChanger and click Switch ROM.

Note for those having experienced the older version 2:

No need to add boot images in Dual-ROM zips any more

.

How to change/update a ROM or Kernel

You have to be on the ROM you want to change/update.

Enter Recovery

If you are changing the ROM or kernel and/or a wipe is needed, install the

DualBoot-Control.zip

and select Wipe current ROM data.

Flash the ROM or kernel and before reboot install the DualBoot-Control.zip and select ROM1 update if you flashed ROM1 or ROM2 update if you flashed ROM2.

Info: There is also the wipe-rom-x-data.sh in /data/dual-boot/ which can be used to delete the non-running Rom’s data. You can also run this from terminal or adb shell to clean the data of the non-running Rom quickly. For example if you are on ROM1 and you want to change the ROM2 run the script, switch to ROM2 but when screen goes black press pwr & vol- to enter recovery.

How to disable Dual Boot

You have to be on the ROM you want to keep.

Enter Recovery

Install the

DualBoot-Control.zip

and select Remove Dual Boot. This will wipe the data of the other ROM and will also remove the SystemChanger app and scripts. Useful if you want to make a clean nandroid backup, to restore after a repartitioning to normal layout with AIO-Toolkit.

Enjoy it !!