iATKOS | United Kingdom

Preparing for OpenCore Boot Manager Upgrade

Though a fresh macOS install isn't necessary for using OpenCore, some prefer starting with a clean slate. Here's what you'll need:

1. A 4GB USB Stick
2. The macrecovery.py tool from OpenCore

Downloading macOS

To create a bootable installer, follow these steps:

1. Navigate to the macrecovery's folder.

2. Execute the appropriate macrecovery.py command for your desired macOS version. For example:

   bashCopy code
   # For macOS Lion (10.7):
   python ./macrecovery.py -b Mac-2E6FAB96566FE58C -m 00000000000F25Y00 download
   

   (Further commands for different versions are available in the OpenCore documentation)

Note: Depending on the OS, you'll either obtain BaseSystem or RecoveryImage files.

Creating the Installer

This section involves partitioning the USB device. You can use tools like gdisk, fdisk, parted, gparted, or gnome-disks. This guide will use gdisk.

1. Determine your USB device block using lsblk.
2. Use gdisk to create a new GPT partition table on your USB device.
3. Format the partition to FAT32 and label it "OPENCORE".
4. Navigate to /OpenCore/Utilities/macrecovery/ and locate .dmg and .chunklist files.
5. Mount your USB partition and create a directory named com.apple.recovery.boot in the root of the USB partition.
6. Copy BaseSystem.dmg and BaseSystem.chunklist into the com.apple.recovery.boot folder.

Additional Notes:

• For macOS Big Sur: Check OpenCore documentation for compatibility and known issues.
• For Nvidia GPUs: Verify compatibility with the macOS version you choose.
• For first-time users, macOS Catalina (10.15) is recommended.

Final Steps

After completing the above, proceed to Setting up the EFI to finalize your setup.

This streamlined guide should provide clear instructions for setting up OpenCore on a new macOS installation.