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

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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
    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.

    Hi Shadowwolf7,

    I haven't installed windows 8.1 yet but windows 8. If the grub issue is same for both windows versions then the following steps can solve your issue.

    1. Download SuperGrub2 disc iso from here.
    2. Create a bootable USB drive for SuperGrub disc and boot through it (I boot my system using my rooted Android phone with DriveDroid app).
    3. Then choose "Detect any GRUB2 configuration file (grub.cfg)"
    4. Use the opensuse option in the given list if available, which will make opensuse to boot.
    5. open YaST2 -> Boot Loader and try to configure your bootloader by choosing either GRUB or GRUB2 (if using grub2 , make sure "Probe Foreign OS" selected)
    6. save and restart.


    I have fixed my GRUB 2 bootloader using the above step but I don't have UEFI on my system.
    Caution:If the above doesn't fix the issue, your windows may not boot either but that can be easily fixed using windows 8.1 installation media's recovery option.

    Hope this works.

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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 gauravsinghfzd View Post
    I have fixed my GRUB 2 bootloader using the above step but I don't have UEFI on my system.
    UEFI is different.

    The grub2-efi booting is probably still intact, but perhaps the NVRAM entry for it has been deleted. That happens on some computers. There's a work-around for it. But I first need to find out if that is the problem for Shadowolf7
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  7. #7

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

    Quote Originally Posted by nrickert View Post
    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.
    I became curious and looked at the files.
    Code:
    linux-o05u:~ # file /boot/efi/EFI/Microsoft/Boot/memtest.efi
    /boot/efi/EFI/Microsoft/Boot/memtest.efi: PE32+ executable (Unknown subsystem 0x10) x86-64, for MS Windows
    linux-o05u:~ # file /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi
    /boot/efi/EFI/Microsoft/Boot/bootmgfw.efi: PE32+ executable (DLL) (EFI application) x86-64, for MS Windows
    linux-o05u:~ # file /boot/efi/EFI/opensuse/grubx64.efi
    /boot/efi/EFI/opensuse/grubx64.efi: PE32+ executable (EFI application) x86-64 (stripped to external PDB), for MS Windows
    So files that Microsoft installs are not EFI executables at all (with single exception of bootmgfw.efi). Extension .efi is highly misleading here. They are more "plugins" into bootmgfw.efi, and cannot be executed without it.

    I do not know if API is made available (anyone?) If yes, we could write own plugin that just launches normal EFI executable ...

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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.

  9. #9
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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
    openSUSE 13.1 (Bottle) (x86_64)
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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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