Windows 10 - dual boot partitioning


We have had a fair amount of issues relating to Windows 10 and dual-booting.

I believe a lot of trouble comes from using BIOS partition scheme with UEFI and we also say - my self included - the combining BIOS partition scheme with UEFI boot is a no go.

But how true is the statement? I am in a state of confusion right now regarding this issue.

I have been asked to rework a computer to dual boot with Windows 10 / Ubuntu and because Windows 10 needs to be reinstalled and I would have Windows not placing partitions outside a defined size of 64GiB - I have cleaned the disk and used cgdisk to create a GPT partition scheme with a 64GiB partition at the very beginning of the disk and a placeholder partition for the rest.

Now, starting the Windows installation and selecting the 64GiB partition - Windows refuse to install because the partition scheme is GPT.

The system setup in the firmware to boot UEFI and with secure boot disabled.

OK then, let’s tell windows to use a 32GiB partition for install and see what it does.

Reboot into live Manjaro and do a sudo fdisk -l

Two partitions has been created

  • One 549MiB Type HPFS/NTFS/exFAT
  • One 31.5G Type FAT16

What? Confused? Indeed I am!

November 14, 2018 8:42 AM
Checking with BIOS - sneaked in CSM boot - disabled - trying again.
It seems disabling secure boot enabled CSM - retry.

1 Like


We may need some Windows experts for troubleshooting.:sweat_smile:
I guess this should go to OtherOS category?
I don’t see a linux problem here… :wink:

1 Like


Solution 2 maybe helps you(Be careful). I encountered the problem, I used a third-party application on the Windows 10 to convert to all disk without clearing it. I don’t know how to do it on the Linux.



I have to ask if you used Rufus (with UEFI option) or WoeUSB to create your Windows installation media. Also deleting partition and selecting corresponding empty space in Windows installer as the installation destination may help too.



Just wipe that disk and let Win10 take it all. After that use the windows disk manager to shrink the partition to 64GB and install ubuntu on the remaining free space. Don’t be stubborn and try to do it with linux tools. It is not worth the time to dig into this.



To those with concerns relating to the USB stick and it’s method of creation I can tell it was made using Windows own create USB media tool.

With this particular hardware - Medion AIO - when disabling secure boot - csm became active and the Windows ISO was booted in MBR mode.

This was not obvious so for anyone after me - look out for that before booting for installation.

This was fixed by disabling CSM without enabling secure boot and ensuring booting in UEFI mode.

After installing Linux the system would continue to boot into Windows and no changes to the EFI boot order either using Windows bootmgr or the Linux efibootmgr could change that.

After some trial and error I found I had to disable the Windows boot manager in the firmware. Only then Grub was booted.



I really thankful to you for sharing such useful ideas here. I want to Fix Windows 10 Automatic Repair. Can anyone have any ideas?


closed #9

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.