I have a new computer that comes with UEFI but I'm unable to use Windows 10 and Linux in dual boot, after installation of Linux+GRUB and reboot it loads Windows without showing GRUB, notice that first I install Windows and then Linux, as usual. If I erase all the disk and install only a standalone Linux the GRUB works perfectly. I don't know if the problem is related to Windows 10 or the BIOS configuration.

In the BIOS setup I have UEFI mode active, the SECURE BOOT is disabled and the boot order is USB, CD/DVD, hard disk, OS boot loader and finally network.

My hard disk is 500Gb.

I used 50Gb to install Windows (partitions generated by Windows are EFI System, Microsoft reserved, Microsoft basic data and Windows recovery)

For Linux, I created /boot/efi 500Mb, / 50Gb and swap 8Gb (no /home partition, all in / root).

FIRST TRY: I created an EFI partition mounted in /boot/efi, installed linux, GRUB is installed without errors, but after boot it loads windows instead of GRUB.

SECOND TRY: I used the EFI partition created by Windows and mounted it in /boot/efi, installed linux, GRUB is installed without errors, but after boot it still loads windows instead of GRUB.

I thought it was a problem with the Fedora distro and tried with KALI and Mint, but still the GRUB is not loading, windows always start automatically.

Any idea of what can be wrong? As far as I understand, Linux can coexist with Windows in a UEFI based system, but it does not work on my laptop.

  • 1
    Can you add the contents of your /boot/efi/EFI/fedora/grub.cfg? – bgregs Jan 2 '19 at 16:19
  • your grub.cfg should have a windows entry otherwise you need to let grub find other bootloaders, you did run os-prober and grub-mkconfig -o /boot/grub/grub.cfg right ? – MADforFUNandHappy Jan 2 '19 at 18:25
  • It may be useful to edit your question, adding the exact commands you run when installing/configuring GRUB, your partition listing (e.g. fdisk -l) and the mount points you had back then. Since you mentioned Fedora: did you follow the guide from it's wiki? Also, you may find useful guidance in Arch Wiki - Dual boot with Windows, which also points you to How to configure GRUB to boot Windows on UEFI. – fra-san Jan 2 '19 at 19:45

The problem seems to be that as you installed Windows first, it's boot entry is above the Linux boot entry, which needs to be loaded for GRUB to show up. To fix this order, try following these steps:

  1. Go into your boot settings, accessible by pressing a specific key during boot (check your laptop's manual)
  2. Find the option to change the OS boot order (Most likely accessible by pressing enter on the OS boot loader entry in the boot order list).
  3. Move the Linux entry above Windows.
  4. Press the key for save & exit and reboot.

This will make Linux boot by default, and GRUB should show up, with an option to boot into windows.

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  • It should be noted that in UEFI, permanently installed operating system get their own dedicated boot entries: in addition to selecting a disk to boot from, the boot entry will also specify the ESP partition on the disk and the bootloader file within the partition. There are also in-OS command line tools to list and manipulate the boot entries: efibootmgr in Linux, and bcdedit in Windows. The firmware configuration menu ("BIOS settings") will not always allow full manipulation of UEFI boot entries. – telcoM Jan 3 at 9:07

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