How to Dual Boot Windows on Macs Running macOS Big Sur via OCLP

How to Install Windows alongside macOS Big Sur Using OpenCore

For users running macOS Big Sur on unsupported Macs via OpenCore Legacy Patcher, dual-booting with Windows is highly supported. This guide details how to create a partition and install Windows without interfering with your patched macOS system.

1. Prerequisites

• Target Hardware: Any Intel Mac running macOS Big Sur via OCLP.
• Required Tools: Windows 10 or 11 ISO file, minimum 16GB USB drive, and Disk Utility.

2. Compatibility Snapshot

• Supported Configurations: Install Windows on a separate APFS partition or a separate physical drive.
• Boot Manager: OpenCore will display the Windows Boot Option automatically after installation.

3. Installation Preparation

1. Partition your disk: Open Disk Utility on macOS. Select your internal disk, click Partition, add a new partition formatted as MS-DOS (FAT) or ExFAT, and name it "BOOTCAMP".
2. Create Windows Installer: Use a tool like Rufus on Windows or Boot Camp Assistant on a supported Mac to flash the Windows ISO to your USB drive.

4. EFI and config.plist Review

1. This does not apply to this case because OpenCore handles Windows boot files natively.

5. Post-Installation

1. Boot the Installer: Reboot your Mac, hold down the Option key, select the Windows USB installer, and begin the setup.
2. Format partition: When prompted to select a installation drive, select the "BOOTCAMP" partition, click Format to convert it to NTFS, and proceed with the installation.

6. Troubleshooting

Reported Issue: Windows installer fails to boot

1. Secure Boot Block: If the installer does not boot, ensure SecureBootModel is set to Disabled in your OpenCore configuration.
2. Boot order reset: If the Mac boots directly to Windows after installation, reboot, hold Option, select EFI Boot to load OpenCore, and configure your default startup disk in macOS settings.

7. Dual Boot and Advanced Configuration

• T2 chip emulation: For features like Apple ID sync, avoid enabling T2 SMBIOS on Windows as it can trigger verification flags.

8. Verification, Maintenance and Rollback

• Verify Dual Boot: Ensure both macOS Big Sur and Windows appear in the OpenCore boot picker menu.

9. References and Glossary

• APFS: Apple File System, the default storage layout for modern macOS installations.