Allas when booting from the newly created USB I get only windows (which is the OS on the computer’s disk) The USB has 3 partitions:.: 250 MB unallocated D: 6 GB other (assuming this is xOS) F: Clover 200 MB.: 8.12 GB unallocated (rest of the USB) Files in Clover folder: EFI, Librrary, boot7.
While you don't need a fresh install of macOS to use OpenCore, some users prefer having a fresh slate with their boot manager upgrades.
To start we'll want to grab ourselves a copy of macOS. You can skip this and head to formatting the USB if you're just making a bootable OpenCore stick and not an installer. For everyone else, you can either download macOS from the App Store or with Munki's script.
From a macOS machine that meets the requirements of the OS version you want to install, go directly to the App Store and download the desired OS release and continue to Setting up the installer.
For machines that need a specific OS release or can't download from the App Store, you can use the Munki's InstallInstallMacOS utility.
In order to run it, just copy and paste the below command in a terminal window:
As you can see, we get a nice list of macOS installers. If you need a particular versions of macOS, you can select it by typing the number next to it. For this example we'll choose 10:
This is going to take a while as we're downloading the entire 8GB+ macOS installer, so it's highly recommended to read the rest of the guide while you wait.
Once finished, you'll find in your ~/macOS-Installer/
folder a DMG containing the macOS Installer, called Install_macOS_11.1-20C69.dmg
for example. Mount it and you'll find the installer application.
/Applications
folder, as we'll be executing commands from there.~/macOS-installer
From here, jump to Setting up the installer to finish your work.
This method allows you to download much older versions of OS X, currently supporting all Intel versions of OS X(10.4 to current)
Now we'll be formatting the USB to prep for both the macOS installer and OpenCore. We'll want to use macOS Extended (HFS+) with a GUID partition map. This will create two partitions: the main MyVolume
and a second called EFI
which is used as a boot partition where your firmware will check for boot files.
Next run the createinstallmedia
command provided by Apple(opens new window). Note that the command is made for USB's formatted with the name MyVolume
:
This will take some time so you may want to grab a coffee or continue reading the guide (to be fair you really shouldn't be following this guide step by step without reading the whole thing first).
You can also replace the createinstallmedia
path with that of where your installer's located (same idea with the drive name).
Pulled from Apple's own site: How to create a bootable installer for macOS(opens new window)
For systems not supporting UEFI boot, see below:
To start, you need the following:
/Utilties/LegacyBoot/
Within your OpenCore build folder, navigate to Utilities/LegacyBoot
. Here you'll find a file called BootInstall_ARCH.tool
. What this does is install DuetPkg to your desired drive.
Now run this tool in terminal with sudo(This tool will likely fail otherwise):
This will give you a list of available disks, choose yours and you will be prompted to write a new MBR. Choose yes[y]
and you'll be finished.
This will provide you with an EFI partition with either a bootia32 or bootx64 file
Setting up OpenCore's EFI environment is simple – all you need to do is mount our EFI system partition. This is automatically made when we format with GUID but is unmounted by default, this is where our friend MountEFI(opens new window) comes in:
You'll notice that once we open the EFI partition, it's empty. This is where the fun begins.