I'm trying to install Windows 8.1 in UEFI mode on my Mac Pro 4,1 flashed to 5,1 with 3.46GHz Intel W3690.
As far as I can tell, Windows will only create media that boots the way the box that creates the media is booted. If the box booted via BIOS/CSM, the media it creates will (only) install Windows in BIOS/CSM mode. If the box booted via UEFI, the media it creates will install Windows in UEFI mode.
All the instructions I've found around the web for creating UEFI install media involve selecting UEFI mode in a PC's BIOS screen and creating the install media. Of course, we don't have that option.
EDIT: SOLVED!!
The solution is to remove the bootmgr file from the root of the install USB. Note that the USB MUST be formatted as a single partition GPT disk in order to get a 4,1 or 5,1 Mac Pro to boot in UEFI mode. It may or may not work with other hardware that allows access to the EFI firmware, but if a Mac Pro finds an MBR, it boots in BIOS/CSM.
Furthermore, at least on my particular Mac Pro (as mentioned, a 2009 4,1 flashed to 5,1) it did not work when I formatted the USB drive using Apple's Disk Utility OR Gdisk - Sorry, Rod Smith. You are a legend and you have taught me much, but I had to use Windows diskpart to format the USB drive.
So, here is the exact step-by-step:
From any windows environment (I was booted in BIOS/CSM on my Mac Pro) open a command line prompt and type:
Then, still in Windows, I mounted the ISO I'd downloaded from MS and simply dragged everything EXCEPT the bootmgr executable to the root of the USB drive. Note that I did copy bootmgr.efi, just not bootmgr.exe.
Reboot holding alt/option, select the USB drive labeled "EFI Boot" and follow the instructions.
Here's what I've done:
I initially ran into the fairly well documented "select the CD rom type issue", but worked around that by following the instructions here and I successfully created a Windows 8.1 DVD using a PC, an ISO downloaded from Microsoft, oscdimg and ImgBurn.
I installed Windows 8.1 and upgraded it to Windows 10. You'd think I'd be happy and move on, but I have to make things difficult.
I formatted the target drive as a GPT drive according to these instructions, but when I try to install to it, the Windows installer (booted in BIOS/CSM) tells me that it can't install to a GPT formatted drive.
I successfully hacked my Bootcamp Assistant Info.plist and have the option to create a USB drive to install Windows 7 or later using Bootcamp Assistant. BCA reports copying Windows files, downloads the Bootcamp files and then simply reports that the install could not be completed.
However, the USB drive appears to have all the necessary files to install Windows, just not the bootcamp files. I have bootcamp files from a separate download and they installed without issue to the BIOS/CSM version previously mentioned.
No matter what method I use to create the USB - Bootcamp, Rufus on Windows or by manually building it Windows - the USB shows the now familiar blue windows for a few seconds, then goes to a big blue screen and tells me:
Your PC needs to be repaired.
An unexpected error occurred.
Error Code: 0xc0000001
Use your install media to repair your PC or contact your Sys Admin...
My Mac Pro shuts down after 30 seconds or so.
TIA
As far as I can tell, Windows will only create media that boots the way the box that creates the media is booted. If the box booted via BIOS/CSM, the media it creates will (only) install Windows in BIOS/CSM mode. If the box booted via UEFI, the media it creates will install Windows in UEFI mode.
All the instructions I've found around the web for creating UEFI install media involve selecting UEFI mode in a PC's BIOS screen and creating the install media. Of course, we don't have that option.
EDIT: SOLVED!!
The solution is to remove the bootmgr file from the root of the install USB. Note that the USB MUST be formatted as a single partition GPT disk in order to get a 4,1 or 5,1 Mac Pro to boot in UEFI mode. It may or may not work with other hardware that allows access to the EFI firmware, but if a Mac Pro finds an MBR, it boots in BIOS/CSM.
Furthermore, at least on my particular Mac Pro (as mentioned, a 2009 4,1 flashed to 5,1) it did not work when I formatted the USB drive using Apple's Disk Utility OR Gdisk - Sorry, Rod Smith. You are a legend and you have taught me much, but I had to use Windows diskpart to format the USB drive.
So, here is the exact step-by-step:
From any windows environment (I was booted in BIOS/CSM on my Mac Pro) open a command line prompt and type:
Code:
diskpart
list disk
sel disk *N* (where *N* is the number of your USB drive from the list)
clean
convert gpt
format quick fs=fat32 label="NAME"(where NAME is whatever you want to call your USB. Use quotes if you want to use a space, i.e. label="Windows 10")
exitThen, still in Windows, I mounted the ISO I'd downloaded from MS and simply dragged everything EXCEPT the bootmgr executable to the root of the USB drive. Note that I did copy bootmgr.efi, just not bootmgr.exe.
Reboot holding alt/option, select the USB drive labeled "EFI Boot" and follow the instructions.
Here's what I've done:
I initially ran into the fairly well documented "select the CD rom type issue", but worked around that by following the instructions here and I successfully created a Windows 8.1 DVD using a PC, an ISO downloaded from Microsoft, oscdimg and ImgBurn.
I installed Windows 8.1 and upgraded it to Windows 10. You'd think I'd be happy and move on, but I have to make things difficult.
I formatted the target drive as a GPT drive according to these instructions, but when I try to install to it, the Windows installer (booted in BIOS/CSM) tells me that it can't install to a GPT formatted drive.
I successfully hacked my Bootcamp Assistant Info.plist and have the option to create a USB drive to install Windows 7 or later using Bootcamp Assistant. BCA reports copying Windows files, downloads the Bootcamp files and then simply reports that the install could not be completed.
However, the USB drive appears to have all the necessary files to install Windows, just not the bootcamp files. I have bootcamp files from a separate download and they installed without issue to the BIOS/CSM version previously mentioned.
No matter what method I use to create the USB - Bootcamp, Rufus on Windows or by manually building it Windows - the USB shows the now familiar blue windows for a few seconds, then goes to a big blue screen and tells me:
Your PC needs to be repaired.
An unexpected error occurred.
Error Code: 0xc0000001
Use your install media to repair your PC or contact your Sys Admin...
My Mac Pro shuts down after 30 seconds or so.
TIA
Last edited:
