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lion10 Author

Level 1

15 points

The ultimate way to install Windows 8.x in (U)EFI mode on Apple systems

Well, all these solutions regarding Windows 8 (or 8.1) installation methods in this forum seem to be quite complicated. Here follows my favourite way for installing Windows 8.x on Apple EFI systems.

First, once and for all, forget Boot Camp! Because Windows 8 is fully EFI compliant, Boot Camp is totally useless. You only need it to get all the Windows drivers. When using Boot Camp with Windows 8 in EFI mode you get very likely even greater problems. The root of the most Windows 8 install errors reported here is located in Apple’s special "hybrid MBR" GPT layout. Nothing else!

So, in consequence, you have just to remove / replace that "hybrid MBR" with a standard GPT "protective MBR". This change will NOT affect OS X or any other OS X program in any way!

1. Use the OS X Disk Utility to create a partition scheme of your wishes.

2. Download in OS X the tool "GPT fdisk". Install it and start it in terminal with:

sudo gdisk /dev/disk0 or sudo gdisk /dev/disk1

Type p to view the partition table (verify that you have selected the right drive)

Type x to enter experts menu

Type n to create a new clean "protective MBR" (GPT fdisk will NOT report any changes)

Type w to save your changes

3. Start Windows 8 setup in EFI mode; - switch to "Windows prompt" under "repair tools". Start command diskpart. Check your partition; - select that one with name "EFI". Add the drive letter "b" with the command assign letter=b. (Note, this point is perhaps not needed at some systems.)

4. Exit diskpart, start again Windows 8 setup installer from prompt with command setup.

In Windows setup you have now just to format the Windows partition, - the setup installer is now able to update the Apple EFI Boot record properly. You should not get the "Windows could not update the computer's boot configuration. Installation cannot proceed." message.

I can confirm that this install method has worked perfectly for several MacBook, iMac and Macmini computers. Furthermore you should be also able to install Linux smoothly with EFI mode in dual or triple boot configurations. (Don’t know but Linux may have the same troubles like Windows with Apple’s "hybrid MBR" GPT layout.)

Finally big thanks to Roderick W. Smith for his great GPT fdisk tool!! And also a big thanks to user "riseyth" which has given the diskpart EFI "assign letter =b" hint in this forum. (list of references: http://superuser.com/questions/508026/windows-detects-gpt-disk-as-mbr-in-efi-boo t/508454#508454)

Posted on Apr 16, 2014 11:54 AM

58 replies

Oct 5, 2015 3:32 PM in response to TrashTreasury

Thank you for this guide. Though I had to do some additional steps to get Windows 8.1 (and eventually Windows 10) working.

The setup stopped after I selected the partition I wanted to install to. It went to the next screen (with the next steps and progress in percent) and then showed the dreaded "Windows could not prepare the computer to boot into the next phase of installation" message.

Seems the error shows up, because of the PCI SSD-Part of my iMacs Fusion drive.

Here are my Steps:

- Backup MacOs

- Prepare USB-Stick with Bootcamp Assistant and prepare the Windows partition

- In Windows Setup (partition selection) press shift+F10 to access the console

DISKPART

SELECT DISK 0

Attention! This will erase the SSD!

CLEAN

CONVERT GPT

Even if we don't want to install windows onto the SSD we have to create a partition else Windows will write and install to the SSD.

It is important that you leave some space on the SSD after the partition. It seems that Windows setup temporarily writes some stuff into this space. My SSD is 120GB.

CREATE PARTITION PRIMARY SIZE=113000

EXIT

Back to the partition selection screen you can now select the partition Bootcamp created for you on the second disk and format it to NTFS.

Click next and Windows should finally install now.

After windows is done installing. You have to recreate your Fusion-Drive and restore (or reinstall) MacOs.

Boot into the MacOs recovery system and open the terminal

You have to delete the remainder of the old Fusion-Drive

diskutil cs list

(Copy the ID of the Volume Group)

diskutil cs delete CopiedID

(Clear SSD, Windows doesn't seem to need anything here)

diskutil erase disk free space disk0

(Create Fusion Drive)

diskutil cs create Fusion disk0 disk1s2

(Copy the new ID and create the volume on the Fusion-Drive)

diskutil cs createVolume NewId JHFS+ "Macintosh HD" g0

Now restore (or reinstall) MacOs.

I have no idea why I have to do all these steps now. Early 2014 I just had to install it with Bootcamp-Assistant alone. Now I had to jump through several hoops and waste several days to find out these steps. Back then it was pre Yosemite, maybe the old Version of the Bootcamp-Assistant did this stuff to the SSD automatically.

Hope this helps.