Daniel miller

Q: El Cap won't dual boot Windows 8.1 w/ EFI

I have a 2009 Mac Pro. Upgraded the procs to dual x5690 and "flashed" it to read as a 5,1. Running a GTX 980 and Quadro K4000. 64 Gb ram. OSX installed on a owc pcie ssd, Windows installed on Samsung 850 pro plugged into spare sata connector in optical bay.

 

 

My quandary: I was running Yosemite and Windows 8.1 in harmony. Each one on its own drive, not two partitions of the same drive. I upgraded to El Cap. I could no longer boot into Windows if my El Cap drive was plugged in. I did some research and saw that El Cap doesn't like MBRs so I did a clean install of Windows after switching it over to EFI but it still won't boot. I use startup disk utility, and it reboots and just sits on a black screen.

 

 

Is there a way to get this sorted? Do I have to disable this new SIP feature that seems to be wreaking havoc on all sorts of folks? Help me Obi-Wan Kenobi....

Mac Pro, OS X El Capitan (10.11.1), Windows 8.1

Posted on Dec 11, 2015 9:51 AM

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Q: El Cap won't dual boot Windows 8.1 w/ EFI

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  • by Loner T,

    Loner T Loner T Jan 8, 2016 11:49 AM in response to Daniel miller
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    Jan 8, 2016 11:49 AM in response to Daniel miller

    I was planning to refer you to this one - https://support.microsoft.com/en-us/kb/927392 .   But your link should also work. Please see the comments section in your link for some issues and their resolutions.

  • by Daniel miller,

    Daniel miller Daniel miller Jan 8, 2016 2:01 PM in response to Loner T
    Level 1 (5 points)
    Jan 8, 2016 2:01 PM in response to Loner T

    hmmm, so the bootrec.exe/fixboot made the EFI partition unreadable... So I reformatted that partition to FAT32 again and assigned it the drive letter v:. Then I entered this command "bcdboot c:\Windows /l en-us /s v: /f ALL" Upon exiting command line and back into the recovery OS I hit "continue to windows 8.1" at which point it booted into windows. Great. Time to run some tests. So, i hit my bootcamp diamond, selected my OS X drive and booted into OS X. Great. In OS X I entered the startup disk util and selected my windows partition. It wouldn't boot. No go. So I reboot and hold option. It brings up the disk selection but its a little different this time.


    IMG_0014_sm.jpg

    I now have 2 EFI Boot options. So I selected the second 1, and the machine booted into Windows. Using diskpart I checked, there is still only 1 EFI partition on the windows disk and 1 EFI partition on the OS X disk. So I hopped over to OS X and again mounted the EFI partitions to see what was up. I see something that I think is strange, but I'm still out of my element here. So look at these photos and tell me if two different "Microsoft" in the OS X EFI partition folders are the issue. Something to note, just in case it isn't obvious: the OSXEFI is the EFI partition for OS X and WINDOWS is the EFI partition for Windows.

    Screen Shot 2016-01-08 at 1.35.19 PM.png

    Screen Shot 2016-01-08 at 1.35.26 PM.png

    Screen Shot 2016-01-08 at 1.38.51 PM.png

    Screen Shot 2016-01-08 at 1.38.55 PM.png

    Screen Shot 2016-01-08 at 1.38.59 PM.png

    Screen Shot 2016-01-08 at 1.39.02 PM.png

     

    I also notice that I no longer have the "EFI > Apple" Folder that I had earlier. this is obviously because I reformatted the partition, but I don't know how it got there to begin with. Does that folder need to be present somewhere as well?

  • by Loner T,

    Loner T Loner T Jan 8, 2016 3:09 PM in response to Daniel miller
    Level 7 (24,307 points)
    Safari
    Jan 8, 2016 3:09 PM in response to Daniel miller

    The two EFI Boot entries are one each from the OS X disk and Windows disk respectively. The Microsoft tree from the OS X disk should be deleted, which will remove it from the screen shot you posted. Once you have it cleaned from the OS X Disk, then try System Preferences -> Startup Disk.

     

    The correct structure is shown in Re: Can't resize Macintosh HD partition .

  • by Daniel miller,

    Daniel miller Daniel miller Jan 8, 2016 3:50 PM in response to Loner T
    Level 1 (5 points)
    Jan 8, 2016 3:50 PM in response to Loner T

    Ok, I deleted the Microsoft tree that was in the root of the EFI partition and that didn't seem to do anything. Should i delete the Microsoft tree that is in the EFI FOLDER as well?

  • by Loner T,

    Loner T Loner T Jan 8, 2016 4:23 PM in response to Daniel miller
    Level 7 (24,307 points)
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    Jan 8, 2016 4:23 PM in response to Daniel miller

    If EFI disk is mounted at /Volumes/EFI, then you will need to delete and its contents

     

    /Volumes/EFI/EFI/Microsoft:

    total 9

    drwxrwxrwx  1 staff  4096 26 Aug 15:35 Boot

    drwxrwxrwx  1 staff   512 26 Aug 21:07 Recovery


    from the OS X SSD.

  • by Daniel miller,

    Daniel miller Daniel miller Jan 11, 2016 10:12 AM in response to Loner T
    Level 1 (5 points)
    Jan 11, 2016 10:12 AM in response to Loner T

    Ok, I got rid of the extra "EFI Boot" from my hold option while booting screen, but I still can't jump into windows using the startup disk tool. Do you have a screen shot of what my Windows disk EFI partition should look like so I can just mirror it? I feel like I'm right on the edge of having this thing working... Thanks for all your help again, I greatly appreciate it.

  • by Loner T,

    Loner T Loner T Jan 11, 2016 10:25 AM in response to Daniel miller
    Level 7 (24,307 points)
    Safari
    Jan 11, 2016 10:25 AM in response to Daniel miller

    You may want to look at http://neosmart.net/EasyBCD/ to correct the BCD on the Windows disk. The correct layout is shown in Re: Can't resize Macintosh HD partition .

     

    Another option to consider is to convert the Windows disk to an MBR disk, but it has own limitations.

  • by Daniel miller,

    Daniel miller Daniel miller Mar 19, 2016 2:25 PM in response to Loner T
    Level 1 (5 points)
    Mar 19, 2016 2:25 PM in response to Loner T

    Long time no see.... I know.

    I had essentially given up on trying to get this to work the way it used to.

    Recently I picked up two SM951 blades and installed Windows 10 and El cap on their own respective blades and hoped that this fresh install might get me back to being able to use Startup Disk interface to boot from El Cap to Windows. It didn't, however now I get the "No Bootable Device" message when I try it. Before I would just get a black screen. So I started moving all sorts of files around in my EFI partitions trying to get it to work when I noticed something. Every time I use Startup Disk (Startup Disk > Select Bootcamp > restart button) The disk identifiers for my two drives would swap.

     

    As an example: In terminal I enter diskutil list which tells me that the EFI partition on my Bootcamp disk is disk0s1. Open startup disk select bootcamp, and hit restart. Computer restarts but takes me to a black screen and flashes "No bootable device". Hold power button to power down. Hit power button to start up, holding option key. Select OS X. Back to terminal diskutil list NOW  MY EFI PARTITION IS disk1s1.

     

    Is my disk identifier changing on restart and thus "misplacing" my Windows boot manager? Is there a way to lock the disk id to prevent this from happening?

  • by Loner T,

    Loner T Loner T Mar 19, 2016 4:04 PM in response to Daniel miller
    Level 7 (24,307 points)
    Safari
    Mar 19, 2016 4:04 PM in response to Daniel miller

    Once you click on restart, the NVRAM should be set to the full physical hardware path of the disk, and the renumbering of the disk is due to switching back to OSX which can cause the discovery to be different.

     

    You can check the physical path by running diskutil info or run nvram -p which should provide the correct path.

  • by Daniel miller,

    Daniel miller Daniel miller Mar 23, 2016 4:25 PM in response to Loner T
    Level 1 (5 points)
    Mar 23, 2016 4:25 PM in response to Loner T

    Another dead end...

     

    So then, when I select "bootcamp" from the Startup Disk dialogue, where is that looking? What file is it pointing to? the bootx64.efi in the EFI > boot folder? Will copying my bootmgfw.efi to that same folder and renaming it bootx64.efi (thus replacing the old one) help in any way?

     

    Also, after a bunch of research I notice that I'm supposed to have an Apple folder that has a lot of files in it, I do not have that. Is there somewhere I can get those files? would they be the cause of this "No bootable disk" problem?

  • by Loner T,

    Loner T Loner T Mar 23, 2016 4:40 PM in response to Daniel miller
    Level 7 (24,307 points)
    Safari
    Mar 23, 2016 4:40 PM in response to Daniel miller

    Daniel miller wrote:

     

    Another dead end...

     

    So then, when I select "bootcamp" from the Startup Disk dialogue, where is that looking? What file is it pointing to? the bootx64.efi in the EFI > boot folder? Will copying my bootmgfw.efi to that same folder and renaming it bootx64.efi (thus replacing the old one) help in any way?

    The Microsoft folder on your EFI partition should have all the necessary files. The Bootcamp location is the NTFS partition containing your Windows installation.

     

     

    Also, after a bunch of research I notice that I'm supposed to have an Apple folder that has a lot of files in it, I do not have that. Is there somewhere I can get those files? would they be the cause of this "No bootable disk" problem?

    Can you check Re: Can't resize Macintosh HD partition for the listing of files and directories that you should have. The Apple folder is usually rebuilt when you install OSX on the disk or run a diskutil repairDisk on the disk.

  • by Daniel miller,

    Daniel miller Daniel miller Mar 23, 2016 4:46 PM in response to Loner T
    Level 1 (5 points)
    Mar 23, 2016 4:46 PM in response to Loner T

    Right, My microsoft folder has everything, I'm assuming it works since when I hold option on start up I can select the disk and windows boots. for some reason using the Startup Disk dialogue does NOT select the correct folder/file/whatever. So I'm wondering if the Startup Disk selection looks somewhere else? Other wise why would one method work and the other not?

     

    I have no apple folder at all. Which disk should I run the repairDisk on to get it to rebuild that file tree?

     

    Thank you for your help.

  • by Loner T,

    Loner T Loner T Mar 23, 2016 5:25 PM in response to Daniel miller
    Level 7 (24,307 points)
    Safari
    Mar 23, 2016 5:25 PM in response to Daniel miller

    If you try a SMC and NVRAM Reset, does it allow Bootcamp to be selected and work? The EFI partition that is missing the Apple folder is the disk on which you would run the diskutil RepairDisk. The number N in diskN can change based on disk discovery.

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