CoolBooter

CoolBooter is a tool for dual booting jailbroken 32-bit iOS devices with another copy of iOS via winocm's ios-kexec-utils. It supports hosts running iOS 7.0 or higher and can boot versions ranging from 5.0 to 8.4.1. Hosts on lower versions can install the CLI version instead.

Usage notes

 * During setup, the user can choose to jailbreak the secondary operating system and/or activate verbose boot. iOS 8.x will automatically be jailbroken, as there will be issues if it is not.


 * Hosts running iOS 9.0 or higher experienced issues with data protection, meaning that apps such as YouTube, WhatsApp and Mail would not work on the secondary OS. Experimental protected volume support was added later to work around these issues.


 * Like regular installations of iOS, dual booted systems must be activated. A6 devices that have ever been on iOS 10 and then downgraded have failed activation since July, 2017, first randomly, then consistently. To activate the dual booted partition on these devices, activation records can be copied to  from the host OS. Another option is to delete , also done from the host OS.


 * iOS 6 as a secondary OS will kernel panic during boot on Lightning adapter devices if the USB cable is attached, or has been since the device was booted into the host OS. To fix the issue, unplug the cable and reboot before launching CoolBooter.


 * The secondary OS uses the same lock screen passcode as the host OS, and is protected under the same data-protection scheme as the main OS.


 * Prior to version 1.4 (APP), CoolBooter used a kloader version that depended on tfp0. This meant that CoolBooter would not function on h3lix, which does not have tfp0 but instead has hgsp4. Version 1.4 was released a few days after h3lix to add support.

CoolBooterCLI
A command line interface version called CoolBooterCLI is offered as a separate package in Cydia. Originally requiring iOS 6.0 or higher, it now runs on iOS 5.x as well.

Starting CoolBooterCLI from MTerminal using the command  fails on devices running older iOS versions. This issue can be solved by starting CoolBooterCLI via SSH instead or by using an app that spawns "coolbootercli -b".

CoolBooter Untetherer
An extension for CoolBooter that allows the user to "untether" their CoolBooter install exists in the form of CoolBooter Untetherer. When installed, the second OS installed by CoolBooter will automatically be booted into without any user input. To disable the untether, the user must hold the volume down button on their device until their main OS lockscreen shows.