iOS Multiboot

Here is another iOS multibooting guide. This one mostly covers the "untethered nand_firmware flash boot method" for which I worked on back in 2016 when I did my first iOS multiboot attempts. Those were nostalgic good times :^)
Warning : Some parts of this tutorial involve low-level components that may contain critical information for the device to work properly. A simple mistake can definitively brick the device, making it completely useless. Do not try on newer devices if you care about jailbreak, latest firmwares might be patched.
No warranties given, follow this guide on your own risk, you are on your own

List of contents

Requirements

Introduction

Part 1: Downloading iOS firmwares

Part 2: Preparing workspace

Part 3: Decrypt firmware images

Part 4: iOS bootchain basics

Part 5: Patching LLB and iBoot

Part 6: iOS Dataprotection basics

Part 7: Patching DeviceTree

Part 8: Flashing nand_firmware

Part 9: Preparing main iOS

Part 10: LwVM Disk Partitionning

Part 11: Restoring iOS system images

Part 12: Completing installation

Credits/Thanks to

@nyan_satan for his iOS dualboot writeup , many many advices and this awesome website template.

@danzatt for his iOS dualboot writeup , gptfdisk compiled for iOS and hfs_resize

@winocm for the initial kloader

@xerub for advices and the improved version of kloader

@iH8sn0w for advices

@JonathanSeals for advices and multi_kloader

@axi0mX for iOS 4, iOS 5 and 64-bit kloader support

Roderick W. Smith - for gptfdisk