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macOS OpenCore Patcher

Installation to HDD with dualboot

How to proceed with BootCamp

Check my comment on reddit

Hi, I just installed OC on my 2 2017 iMacs, both with bootcamp. There is no issues at all and one iMac shows OC "EFI Boot" also after install on HDD. 2nd iMac didn't show that boot menu item (when holding Option key during startup), so I fixed it like this: Before you install OC on HDD

mount EFI partition (diskutil list, sudo mount ...)
rename Microsoft folder to Microsoft-BAK and delete Boot/boot folder
    (or move it somewhere to USB Flash. I didn't need it later.)
umount EFI partition using diskutil
Install OC on HDD and remove USB Flash
Reset PRAM
Reboot with Option hey holding and select OC EFI Boot and then macOS Sonoma
mount EFI, rename MS folder back and unmount, reboot with Option key
Now naming was wrong, OC EFI Boot name is Windows with OC icon.
    Select it and you can see now proper naming and icons. Select macOS ...
Set Startup Disk to Macintosh HD or where you Sonoma is

This way both my iMacs boot to Sonoma automatically. Hope it helps.

Installation

If the EFI Boot menu item (where the OCP EFI part is) is not displayed when installing on a dual boot HDD (Windows), you need to move the Boot/boot directory (delete) in the EFI partition (under the EFI/ directory) and rename the Microsoft directory to Microsoft-BAK.
Afterwards, the OCP installation into EFI on the HDD should go through fine and during boot the OC EFI Boot (or with the Windows name but the OCP icon) should appear even without the USB Flash (which we have to remove before restarting).
Then Shutdown with PRAM reset (option command P R and Startup button)

Restore Microsoft Windows in the EFI menu

Just remount the EFI partition after booting macOS and rename Microsoft-BAK to Microsoft.
In the EFI menu (Hold Option key before chime boot sound) it will say Windows, but the icon will be OCP (OpenCore Patcher).
MacOS and Windows can be started after selecting the OCP icon (now named Windows) :)

Boot into macOS - if not selected automatically

Just set the Startup Disk to Macintosh HD.

Recovery

https://dcg-ipod.affinityco.net/blogs/help-2/kb-60604-reinstalling-macos-on-a-device-with-opencore
Follow the steps in the app. You will need to:

  • Download a copy of the macOS installer. You can choose from a list of different versions - it is recommended to use the same version that you have currently installed. Check which version you have by viewing About this Mac in the Apple menu.
  • Copy the macOS installer to a USB drive
  • Install OpenCore to the USB drive

If you can't follow these steps on your Mac because you can't use it, then you will need to use another Macintosh computer to do so. We recommend preparing a Recovery USB drive ahead of time - make it a part of your backup plan for your data.

To use your Recovery drive, turn off your Mac. Then:

  • Turn on your Mac whilst holding cmd + opt + P + R until you hear the chime twice
  • Hold opt until you see a menu appear
  • Choose OpenCore / EFI from the menu
  • Choose Install macOS from the next menu that appears