UEFI Dual booting issues [Solved]

I've finally built my new system, which new for me uses a UEFI bios. But I'm having some issues trying to install alongside windows 10.

Win 10 is already installed, with its own EFI partition, on /dev/sdc. This was also an upgrade from Win 7 to 10, so the partition layout is somewhat new. In the past I've always had problems with dual booting and windows, namely windows update would refuse to complete unless the BIOS was configured to boot from the windows drive (IE skipping the GRUB menu).

Windows 10 has created the following:

/dev/sdc1 -- Recovery
/dev/sdc2 -- EFI
/dev/sdc3 -- Reserved
/dev/sdc4 -- C:\ drive

I installed windows by first disabling my nvme drive in the BIOS.

My first attempt at installing Manjaro, to /dev/nvme0n1, prompted me to create a fat32 /boot/efi with a guid partition table. I did this and all seemed fine, windows was in the GRUB menu, but I had no mouse or keyboard upon booting into Manjaro.

I reinstalled Manjaro, which fixed the mouse problem, but now Windows is missing from the GRUB menu. Also, I get errors when trying to boot from the Linux EFI, but booting from the nvme drive itself works. I have a feeling EFI was not used during the second install. I manually set up the partitions and mount points:

/dev/nvmeOn1p4 -- /boot/efi (fat32)
/dev/nvmeOn1p2 -- / (ext4)
/dev/nvmeOn1p3 -- /home
/dev/nvmeOn1p1 -- swap

Did I miss something during the install to cause a non EFI boot loader? Would this also be the reason GRUB, and os-prober/grub-update, cannot find my Windows installation?


Ok, a few blog posts later, I managed to boot Manjaro using the EFI loader. Then ran

sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=manjaro --recheck
sudo update-grub

which added Windows to the GRUB menu. But selecting the Windows option result in an error:

no such device: 6C01-0891
disk 'hd2,gpt2' not found.


Disable "Fast Boot" in the BIOS.

Take a look at this.
Provide info as stated in link if you have problems
What is windows $esp (efi partition) ? Is it sdc2 or /dev/nvmeOn1p4 ?
Is windows really uefi? Do you know how to find that out? Use this if unsure.

[edit] - just saw your edit.
Is windows really bootable before installing manjaro?
Please be honest. It's important (for you).
and provide contents of $esp (if both, then both sdc2 & /dev/nvmeOn1p4) down to .efi file levels.

What happens if you choose Windows as your boot device during startup ? (depending on your PC F12, or another funktion key, another option would be to temporarily alter the boot order within the BIOS)

Are you able to boot into Windows then?

If I configure the BIOS to boot from the Windows EFI, it boots without a problem. Booting the NVME EFI loads GRUB, and boots into Manjaro, but cannot boot into windows. I've verified that the UUID of the Windows EFI partition is correct. But GRUB is having a problem finding that drive.

I've found a few Arch threads with a similar problem, but they all seem to be unsolved. I'm wondering if GRUB has issues when installed on an NVME with the other EFI being on a regular drive.

I am just about to reboot and see if anything in the BIOS is preventing that drive from powering up.

When disabling your drive in the BIOS during the installation of Manjaro it probably failed to "see" Windows when initializing Grub, and therefore Windows is not in the Grub menu as a boot option by default...

You could try to re-install grub: Restore_the_GRUB_Bootloader


Disabling "Fast Boot" in the BIOS fixed the problem. To me, this is a new BIOS with new technology. I'm not sure what this "Fast Boot" is or does, but one thing it does is prevent GRUB from seeing my hard drives.

I disabled the NVME drive during the installation of Windows, which I installed before Manjaro. I didn't want that crappy OS tainting my brand new 970 Pro. I then re-enabled it for the Manjaro install, knowing that its GRUB installer should detect windows.

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