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Thread: Dualboot with Win8.1. Windows overwrites GRUB.

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  1. #1
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    Default Dualboot with Win8.1. Windows overwrites GRUB.

    Ok, so I finally got the courage to attempt a dualboot with Win8 again. Installation was painless after cleaning up C: and then shrinking the volume to make room for the openSUSE partitions. Everything behaved normally (and exceptionally, bravo on 13.1) until I booted into Windows 8.1 again. Now GRUB is totally gone (as expected). I am using a Sony Vaio Fit 15 with Windows 8.1. I installed openSUSE 13.1 64 bit with UEFI and Secureboot enabled. I am also using btrfs as I intent to experiment with getting Bumblebee to work.

    Ideally, I'd like to be able to chainload GRUB from the Windows bootloader so that I won't run into this problem again. I have encountered this problem invariably with Windows 8 on several machines, and am thus unwilling to simply reinstall openSUSE or GRUB. The Vaio uses UEFI and GPT. In this regards EasyBCD does not work with Windows 8.x as it can't handle GPT. Previous installations were rendered inoperative by EasyBCD.

    This problem came as I was writing a tutorial on the topic.

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    Default Re: Dualboot with Win8.1. Windows overwrites GRUB.

    Quote Originally Posted by Shadowolf7 View Post
    Ideally, I'd like to be able to chainload GRUB from the Windows bootloader so that I won't run into this problem again.
    I spent some time looking for ways to do that in a UEFI environment. As best I can tell, it cannot be done. The Windows boot manager does not appear to have suitable capabilities for booting non-Windows systems in a UEFI box.

    On my UEFI box (using to post this message), I use the grub2-efi boot loader and have it load Windows when I want to boot that.
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    Default Re: Dualboot with Win8.1. Windows overwrites GRUB.

    That is precisely the problem though. As soon as I booted into WIndows, then rebooted GRUB2-efi was gone.

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    Default Re: Dualboot with Win8.1. Windows overwrites GRUB.

    Quote Originally Posted by Shadowolf7 View Post
    That is precisely the problem though. As soon as I booted into WIndows, then rebooted GRUB2-efi was gone.
    Did it work before you booted into Windows?
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    Default Re: Dualboot with Win8.1. Windows overwrites GRUB.

    Quote Originally Posted by nrickert View Post
    Did it work before you booted into Windows?
    Yes, it was fine until I booted into Windows from GRUB. Then once I rebooted, GRUB was gone.

  6. #6
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    Default Re: Dualboot with Win8.1. Windows overwrites GRUB.

    Hi. But I am just wondering that in addition to what Rescatux offers at the link. What I've always tried and found to be fairly successful is using the Ubuntu Remix from here:
    https://wiki.ubuntu.com/UbuntuGNOME/ReleaseNotes/12.10

    from the website:

    Since the original Ubuntu GNOME Remix 12.10 release didn't boot on EFI computers, we released a new image (12.10.1) on Tuesday, October 23 to fix this problem.
    I do believe it comes with Boot repair. If it does not, and I'll be surprised that it won't as I usually find it there when I find occasion to use it, open Ubuntu's Terminal

    sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
    sudo apt-get install -y boot-repair && (boot-repair &)
    More info here and I hope it helps you as well:

    https://help.ubuntu.com/community/Boot-Repair
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    Default Re: Dualboot with Win8.1. Windows overwrites GRUB.

    Quote Originally Posted by Shadowolf7 View Post
    Yes, it was fine until I booted into Windows from GRUB. Then once I rebooted, GRUB was gone.
    Here's what you can try. Open an Administrator command prompt in Windows 8. From that command prompt, run:

    Code:
    bcdedit /set {bootmgr} path \EFI\opensuse\shim.efi
    This assumes that you configured opensuse for secure-boot. Otherwise, change that "shim.efi" to "grubx64.efi".

    That tells Windows to use grub as its boot manager. You then use the grub menu to get to Windows.

    To undo that change, you can use
    Code:
    bcdedit /set {bootmgr} path \EFI\Microsoft\Boot\bootmgfw.efi
    which restores the previous value.

    For safety, you might want to first boot linux from a CD or USB, mount the EFI partition, then make sure that "/EFI/opensuse/shim.efi" exists relative to the mount point.

    What I described is working fine for me. Whenever Windows takes over booting, it boots into the grub menu.
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    Default Re: Dualboot with Win8.1. Windows overwrites GRUB.

    In those lines, do I simply copy paste? Or are there variables that I need to adjust?

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    Default Re: Dualboot with Win8.1. Windows overwrites GRUB.

    Quote Originally Posted by Shadowolf7 View Post
    In those lines, do I simply copy paste? Or are there variables that I need to adjust?
    Copy/paste should be fine. But I still recommend that you make sure the referenced file exists in the efi partition. Check from a booted linux USB or CD or DVD. Use something like:
    Code:
    # mount /dev/sda1 /mnt
    # ls -l /mnt/EFI/opensuse
    The "/dev/sda1" might be wrong. It might be "/dev/sda2", or it might be "/dev/sdb1" if a USB boot makes "sda" the name of the USB device.

    You are looking for a file named "shim.efi". Running "parted -l" might tell you which partition is the EFI partition.
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    Default Re: Dualboot with Win8.1. Windows overwrites GRUB.

    On Mon 06 Jan 2014 10:46:01 PM CST, nrickert wrote:


    Shadowolf7;2614271 Wrote:
    > Yes, it was fine until I booted into Windows from GRUB. Then once I
    > rebooted, GRUB was gone.


    Here's what you can try. Open an Administrator command prompt in
    Windows 8. From that command prompt, run:


    Code:
    --------------------

    bcdedit /set {bootmgr} path \EFI\opensuse\shim.efi

    --------------------

    This assumes that you configured opensuse for secure-boot. Otherwise,
    change that "shim.efi" to "grubx64.efi".

    That tells Windows to use grub as its boot manager. You then use the
    grub menu to get to Windows.

    To undo that change, you can use

    Code:
    --------------------

    bcdedit /set {bootmgr} path \EFI\Microsoft\Boot\bootmgfw.efi

    --------------------

    which restores the previous value.

    For safety, you might want to first boot linux from a CD or USB, mount
    the EFI partition, then make sure that "/EFI/opensuse/shim.efi" exists
    relative to the mount point.

    What I described is working fine for me. Whenever Windows takes over
    booting, it boots into the grub menu.


    Hi
    Wouldn't you also need to ensure the system (Windows) does a full
    shutdown, not a hybrid one....

    For example;
    http://www.howtohaven.com/system/how...indows-8.shtml

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