Dual-booting 64-bit devices with HFS Filesystem

Introduction:

As of now dual-boots were popular from 32-bit devices like iPhone 5 , iPad 4 , iPhone 4s etc. Few days ago @Ralph0045 and @mcg29_ released guide for dual-booting 64-bit devices but for APFS Filesystem. Now me to clear dual-booting arm64 devices I'm releasing guide for HFS Filesystems. This is my first guide, so it's not perfect.

Content:

Preparations

Partitioning

Restoring rootFS

Modifying filesystem

Patching bootchain

First boot

Credits:

@exploit3dguy for this updated guide that supports 64-bit devices.
@nyan_satan for original Dual-boot guide
@tihmstar for iBoot64Patcher, img4tool
@xerub for img4lib
@danzatt for gptfdisk, hfs_resize
@axi0mX for checkm8 BootRom Exploit
Preparations