Bypassing Boot Camp to install Windows using a non-standard partition scheme

My new Retina MacBook Pro is on its way, giving me time to contemplate setting it up. Good thing I got started—I had no idea how difficult it was going to be to install Windows and create an auxiliary data partition. I've been a Mac user for years, and have kept my files separate from the system disk since the days of System 7, but I haven't upgraded to a new Mac since Snow Leopard and built-in optical drives.

Boot Camp is Apple's solution for this, but it doesn't work on drives that have any non-standard partitions. Beyond whatever "user experience" logic Apple may have for this, there's a simple technical explanation: the MBR partitioning scheme used by Boot Camp supports a maximum of 4 partitions.

Originally, the Boot Camp engineers had no choice. They was forced into an ugly hack workaround involving the use of a hybrid GPT/MBR scheme (basically overlaying an MBR scheme on top of a GPT disk) since Windows used to be unable to boot from GPT disks.

That wasn't a problem on my old machine, where I had an optical drive and no OS X recovery partition. Partitioning the new one the way I want means 5 partitions. I find tons of guides and tutorials online that tell me how I can, with a bit of work, interrupt the Boot Camp process and repartition the drive, giving me almost what I want. Except every one that I've seen requires me to give up my recovery partition, since they remain hobbled by MBR's limitation of 4 partitions. I don't want to do that.

I'm wondering if I really have to compromise. Modern 64-bit version of Windows no longer have this limitation—they boot fine from GPT disks on EFI-based computers. Which are the only versions that are officially supported by the current version of Boot Camp, and the only versions that I care to run. So:

1. Is Boot Camp 5 (as provided with OS X Mavericks) still using the hybrid GPT/MBR scheme? Since it explicitly supports only 64-bit versions of Windows 7 and 8, it is possible that they've jettisoned this ugliness. That would be a good explanation for the lack of support for Windows XP and Vista as well as all 32-bit versions. I don't have a lot of confidence here, but maybe all the online tutorials are just old. Has anyone actually tried it?

2. If not, I don't want its grubby paws mucking up my disk. The obvious alternative is to just add a Windows partition manually in Disk Utility, install Windows, and then install the Boot Camp-provided drivers. If I do this, what do I stand to lose? What features/benefits does the Boot Camp Assistant and its associated setup process provide to me?

Solution 1:

I have installed Windows 8.1 Pro via Boot Camp on my MacBook Pro Retina 15-inch mid-2015, with OS X Yosemite 10.10.4 and Boot Camp Assistant version 5.1.4. I can prove that this version of Boot Camp is no longer creating hybrid GPT/MBR partition scheme to install Windows 8 x64 on Intel-based Macs, and Windows is directly booted in EFI mode. Here are what I have tried:

1. Running Ubuntu on its installation flash drive, I ran sudo disk -l /dev/sda to check my local Mac SSD; results: MBR: protective, BSD: not present, APM: not present, GPT: present Found valid GPT with protective MBR; using GPT Therefore Windows is not booting from and running on a disk with hybrid GPT/MBR scheme.
2. In Windows, C:\Windows\panther\setupact.log has one entry: Callback_BootEnvironmentDetect: Detected boot environment: EFI How to tell if windows 7 installer boot in EFI or BIOS?

Therefore theoretically Boot Camp is not needed to install Windows 7/8 x64, which support booting from GPT disks on UEFI(that is EFI 2.x)-based systems. But still it's better to use Boot Camp to create the Windows Installation flash drive and download drivers for Windows. The guide: How to install Windows 8.1 on Mac without Boot Camp To sum it up:

1. Partition your disk as you wish in Disk Utility in OS X; just format your desired Windows OS and data partitions as FAT32.
2. Since Retina MacBook Pros do not come with a SuperDrive, you need to create a Windows Installation flash drive from the ISO file. Please do this in Boot Camp Assistant. I have tried run dd command on Mac's Terminal to copy the ISO, but the created flash drive is not bootable on UEFI Macs: the Apple boot manager simply does not recognize the flash disk.
3. Plug in the flash drive, restart the computer and hold option to open Apple boot manager. You will see a yellow drive called "EFI Boot", which is the Windows Installation. Continue the installation as normal, and format your Windows OS partition as NTFS when asked.
4. Whenever the computer restarts, you need to hold option key and select "Windows" drive on your local SSD to continue installation. Finally go into the system and drivers from Boot Camp will automatically install.

You should keep a Time Machine backup before these operations. Even if things really mess up, you can just create a OS X Yosemite installation flash drive, re-format the SSD to one partition and re-install OS X. How to make a bootable OS X 10.10 Yosemite install driveThe newest version of Recovery HD partition will automatically come back. This worked successfully when I wrongly operated the disk in Ubuntu.

Hope this works!