Install Ubuntu as dual boot after Windows 8 with UEFI secure boot on - aancel/admin GitHub Wiki

This small page is designed to counter problems arising when installing Ubuntu after Windows 8 and using a dual-boot.

First, if Windows is installed in UEFI mode, you should install Ubuntu in the same mode, otherwise you will have to switch modes to go from one system to the other.

  • Use a live image

  • When the live image boots, if you have a list of items then you are in UEFI, but if you have two icons at the bottom the BIOS is not set for UEFI mode (check here)

  • Select try Ubuntu

  • Check the available partitions, there should be a relatively small partition (< 500Mo) marked as bootable. This is the UEFI partition.

  • You can mount it to check the UEFI files.

  • Install Ubuntu

    • Automatic install should ensure that the the /boot/efi partition is taken into account
    • When performing a manual install (notably to separate / from /home), you will have to check if it has been correctly taken into account. After the installation, you can do this either by looking for an entry in /etc/fstab for /boot/efi or by mounting the EFI partition and check that an "ubuntu" directory exists in the "EFI" directory. If it is not present, you can try the boot-repair tool https://help.ubuntu.com/community/Boot-Repair. Check right after that is is present, if not, you might have to search the internet for your specific computer.

  • If the PC doesn't boot up in grub, then Windows might have taken hold of the UEFI boot, to fix this:

    • First take note of the position of the windows boot path in the UEFI bootloader, or better make a backup of UEFI files,
    • Boot into Windows, and check the current configuration of the boot manager with the bcdedit command in an administrator terminal. There is a chance that the path entry of the boot manager references the efi file of Windows.
    • Edit the configuration of the bootloader in an administrator terminal to change the path taken by the boot manager: (ensure that the directory you use exists !)
# Use this line if you have secure boot disabled (recommended)
bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi

# Use this line if you have secure boot enabled
bcdedit /set {bootmgr} path \EFI\ubuntu\shimx64.efi

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