Injecting Grub2 Bootloader into Windows 11 USB Installer for EFI-based Macs
If you're looking to install Windows 11 on a Mac, you'll need a USB installer that's compatible with the EFI-based boot process used by modern Macs. However, the default Windows 11 installer doesn't include support for EFI booting on Macs. In this article, we'll show you how to inject the Grub2 bootloader into the Windows 11 USB installer to make it compatible with EFI-based Macs.
Prerequisites
- A USB flash drive with at least 16GB of storage
- A copy of the Windows 11 ISO file
- A Mac computer with an EFI-based boot process (most Macs released since 2012)
- A USB flash drive formatting tool (such as the
diskutilcommand-line tool on macOS) - The
grub-installandgrub-mkconfigutilities (available in most Linux distributions)
Formatting the USB Flash Drive
The first step is to format the USB flash drive with a GPT partition table and a FAT32 filesystem. This will ensure that the drive is compatible with both the EFI boot process and the Windows 11 installer.
$ diskutil eraseDisk MS-DOS FAT32 WIN11 USB /dev/disk2
Copying the Windows 11 ISO to the USB Flash Drive
Next, you'll need to copy the contents of the Windows 11 ISO file to the USB flash drive. You can use a tool like dd to do this:
$ dd if=Windows11.iso of=/dev/rdisk2 bs=1m
Injecting the Grub2 Bootloader
Once the Windows 11 installer is on the USB flash drive, you can inject the Grub2 bootloader. First, mount the EFI system partition:
$ sudo mkdir /mnt/efi
$ sudo mount -t msdos /dev/disk2s1 /mnt/efi
Next, install Grub2 to the USB flash drive:
$ sudo grub-install --force --target=x86_64-efi --boot-directory=/mnt/efi/boot --efi-directory=/mnt/efi
Finally, generate the Grub2 configuration file:
$ sudo grub-mkconfig -o /mnt/efi/boot/grub/grub.cfg
Booting the Windows 11 Installer on a Mac
With the Grub2 bootloader injected, you can now boot the Windows 11 installer on a Mac. Restart your Mac and hold down the Option key while it boots to enter the startup manager. Select the USB flash drive and press Enter to boot.
- Formatting the USB flash drive with a GPT partition table and a FAT32 filesystem
- Copying the contents of the Windows 11 ISO file to the USB flash drive
- Injecting the Grub2 bootloader into the USB flash drive
- Booting the Windows 11 installer on a Mac