How to install Windows 8.1 on MacBook Pro from USB?

Question

I'm on a 2011 MacBook Pro trying to install Windows 8.1 from a USB. I tried creating bootable FAT32 and NTFS USBs from my Windows ISO with Rufus, but still I don't see anything in Startup Disk in Windows or OS X:

Update 1:

Attempted to write ISO to USB with Disk Utility in OS X, but it wouldn't let me select the ISO (see JeremyKun's comment).

Update 2:

Managed to write the ISO to USB with dd in OS X, but still I don't see it in Startup Disk.

Answer 1

Non-retina display MacBooks cannot boot anything other than OS X from a USB flash drive. It's a limitation in the firmware. Apple fixed this with the retina models because they have no optical drive, meaning USB is the ONLY way to install Windows. On a retina display MacBook, the Boot Camp assistant even makes a USB flash drive for you the same as Rufus does. However, they never backported this fix to non-retina models (and the Boot Camp assistant on non-retina models does not have the USB option).

The only way to boot a USB stick for the purpose of installing Windows is to use rEFInd and bless the rEFInd directory as your startup folder (which itself must be done from the command line as the Startup Disk control panel won't even show it as an option).

rEFInd will then take over the boot process and will allow you to boot to USB media. If you don't like rEFInd you can remove it after Windows is installed. You will then see Windows and OS X as options in the Startup Disk control panel.

Here is a link to the rEFInd home page, and here's how to install and bless the rEFInd directory.

NOTE: Use Disk Utility to create yourself a FAT-formatted partition on the disk BEFORE you attempt to install Windows. This will create the hybrid MBR that Windows needs to boot. You can reformat it NTFS during the Windows install. I you already have an NTFS partition (as your screenshot above shows), you can skip this step as you already have the hybrid MBR created.

Answer 2

I was able to install Windows 7 Ultimate on my MacBook Pro Early 2011 (MacBookPro8,2) using these instructions (archived instructions). Basically you use VM software, such as VMWare, pointed at your bootcamp hard drive partition (instead of to a virtual disk, which is what VM machines normally do) to install windows which makes the bootcamp partition bootable. Then you delete all of the files from the Windows partition and copy all the files from your bootable USB drive. Then, using refind, you can boot to the windows partition, which will start the windows installer you just copied there, and you can install to the same partition.

You already have found instructions for creating the bootable USB drive. (Here are the instructions that allowed me to create the bootable USB from an ISO.) I also needed to download the Bootcamp drivers manually and copy them to the USB drive myself. Instructions for installing refind are available online too. (To avoid System Integrity Protection, I installed refind in recovery mode. Since my downloads folder is on an encrypted disk that I couldn't figure out how to unlock while in recover mode, I copied the refind files to my USB drive and ran them from there while in recovery mode. I still got the SIP warning during the refind install, but the boot manager works.)

Here are the additional steps for posterity (but I recommend referring to the instructions I linked as they go through every step with screenshots):

1. Obtain VMWare (there is a trial version that works.)
2. Create a new custom VM.
3. Using the command line, cd into the package that is your virtual machine. In there, create a new virtual machine disk that points at your bootcamp partition. You will need to determine the disk number and partition number of your bootcamp partition, one way is to inspect it using Disk Utility (e.g. disk1s4, 1 is the disk number and 4 is partition number. Then run this command (while your current directory is the root of your VM package: /Applications/VMware\ Fusion.app/Contents/Library/vmware-rawdiskCreator create /dev/disk[X] [Y] win7_raw lsilogic where you replace [X] with your bootcamp disk number and [Y] with its partition number.
4. Now "show package contents" of your virtual machine, and edit the file named Windows 7 x64.vmx (this will have the name you used for your VM and the extension .vmx. You need to edit two lines to cause the VM to use the VM disk you just created: scsi0.virtualDev=lsilogic scsi0:0.fileName=win7_raw.vmdk
5. Now attach the bootable USB to your VM using the VM options. Start the VM. My disk is encrypted, and I got a password prompt when the VM started. This indicated to me that the VM was correctly configured to use my bootcamp partition. The attached USB should begin installation of Windows on your VM. Since the VM is actually using your bootcamp partition, this will install Windows to your bootcamp partition.
6. But for some reason this version of windows is only part of what you need. I couldn't use the Windows installation as-is. So what you do next is delete all the files from the bootcamp partition and copy over all the files from your bootable USB. (You can install a trial of Tuxera to allow your macOS to write/delete files on an NTFS volume.)
7. Finally, boot to this volume using refind and your windows installer should begin.