How to dual boot OpenCore from a partitioned secondary drive (and manually make the EFI) [IN WINDOWS]

Who this is for: This is for a Hackintosh setup where you have 2 drives, one has windows on it and another is a data drive and you want to install macOS on only portion of the data drive and use the rest of it for.... data. This also allows you to leave the windows boot manager and system partition intact and unaltered.

Just thought i'd post this guide for people facing the same scenario as me where you have a secondary drive and want some of it for data storage and the other part for macOS, WITHOUT LOSING DATA! If you are already on macOS I'm sure there's some alternative way to doing all these steps.

  1. We need our secondary disk to be a BASIC disk, NOT a dynamic one. If your drive is a dynamic disk (you can see if it is in disk management under the disk number), then you're gonna need MiniTool to convert the disk without losing any data:
  • MiniTool method (pretty sure you need the paid version, just google search for the crack or pm me):
    • Open minitool partition manager, right-click desired drive, click convert dynamic disk to basic, hit apply, done.
  • DiskPart method (will lose all data on the drive):
  1. Partition your secondary drive:
  • Open Disk Manager or minitool, shrink your data partition to desired size, leave 200 mb for the EFI and enough for macOS
  • Now create the partition for macOS, format it to exFAT, and name it whatever you want; remember to leave at least 200 mb for the EFI.
  1. Boot your OpenCore USB and install macOS on the partition you created as you normally would, Boot back into windows when complete...

  2. Lets make our EFI:

  • MiniTool method (quick and easy):
    • open minitool, right-click the created EFI partition on the secondary drive, click change partition ID and from the predefined ID dropdown list, select EFI system partition and hit yes, and now click apply and you're done.
  • DiskPart method:
    • open disk management and create a 200 MB FAT partition and name it EFI , for now assign it a drive letter.
    • Move the EFI folder from your opencore USB to the newly created EFI partition, then go back to disk management, right-click the EFI partition and click change drive letters and paths and remove any drive letters.
    • open command prompt, type diskpart and hit enter.
    • type list volume and hit enter; note which volume number is attached to the 200mb EFI partition you created.
    • type select volume # , replacing # with the number you noted and hit enter.
    • type set id=c12a7328-f81f-11d2-ba4b-00a0c93ec93b and hit enter, this will set the parition identifier to an efi system partition.
  1. Finally go into your BIOS and change the boot order to put your secondary drive first so you're greeted with the opencore menu when you switch your computer on.

Now you're done, macOS should boot fine without the USB and so should windows.

If you decide to not want macOS anymore or something goes wrong, just delete the EFI via diskpart, change the boot order back and windows will boot like it used to.

submitted by /u/kevinkochatt
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