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OK, I know that this question has been asked a lot before, but I could not find any questions that exactly relate to my case. I just got a new PC with Windows 10 on an SSD. With my previous PC I had two hard drives, one with Ubuntu, one with Windows 7. I dual booted flawlessly with that setup. Now, I have moved these two HDD's to the new PC, but I would like to know how I can use my HDD with the existing Ubuntu on it to dual boot with the new Windows 10.

In summary:

My new PC has Windows 10 installed.

I moved my HDD containing an existing Ubuntu installation to the new PC.

I would like to set this up such that I can dual boot with windows 10 and ubuntu. Note, both operating systems are already installed on different HDD's, but the ubuntu installation was installed alongside Windows 7 originally (see extra info below). I just need to make them dual boot together. I can already boot into Ubuntu through my BIOS settings (by making the HDD containing Ubuntu the primary HDD), but I would not like to do that every time.

Extra info:

When I boot from the HDD containing Ubuntu, the grub menu comes on, with Windows 7 still as an option, but I cannot boot into Windows 7 though.

Thank you

  • If your new system has Windows 10 then it is UEFI boot. And almost all Windows 7 systems with BIOS boot. UEFI has UEFI Compatibility Support Module (CSM), which emulates a BIOS mode, only available with secure boot off. But UEFI & CSM are not compatible. You can dual boot from UEFI or one time boot key, but not from grub as once you start in one mode you cannot change to other boot mode. Best to plan on full backup of data & reinstall of Ubuntu to gpt partitioned drive with UEFI. You may be able to install grub UEFI boot loader in Windows efi partition for UEFI boot, but really need gpt also. – oldfred Dec 22 '15 at 16:14
  • Best to see details, before making detailed suggestions: Post the link to the Create BootInfo summary report. Is part of Boot-Repair: help.ubuntu.com/community/Boot-Info – oldfred Dec 22 '15 at 17:35

Eventually you need to make an entry for Win10 in grub if the reconfiguration did not add one. Further, you might want to check if the BIOS (EFI or legacy) has a specific boot-order that queries your Linux HDD first. This shows Grub first and lets you decide which system you want to boot.


Try running the following:

sudoo dpkg-reconfigure grub-pc

Select your HDD that contains Ubuntu and let grub rebuild it's boot menu. It should detect and add the Windows Option in your grub menu.


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