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I'm new to Ubuntu and dual booting multiple OS's. I'm pretty noob in general so please bear with me. I've searched around for a few hours and couldn't seem to find what I was looking for, or couldn't understand the answer. Apologies if this question has been answered before.

About two months ago, for the first time, I installed Ubuntu and was dual booting using the rEFInd boot manager to select either Windows 8 or Ubuntu. I had to go through a bunch of steps like disabling secure boot, switching boot modes, etc etc on my Toshiba to get it to work properly. I don't really remember everything I did to get it to work.

Last week I did the free upgrade to Windows 10. Now when my computer boots the rEFInd boot manager does not show up, and I don't know how to access Ubuntu.

  • After updating Windows 10, the installation should not have touched the partition on which Ubuntu was installed, correct? Or do I need to completely reinstall Ubuntu?
  • Therefore, it is just a matter of fixing the boot to enable me to
    choose between OS's, right?
  • If so, how do I go about doing this? I do not see an option in BIOS to disable secure boot now.

This thread seemed pretty close to what I'm asking, but I couldn't quite make sense of it: Ubuntu 12.04 no longer boots on Toshiba Satellite after Windows upgrade

This seems pretty close too, but it seems to be giving me commands for an Ubuntu terminal, which I cannot currently access: http://howtoubuntu.org/how-to-repair-restore-reinstall-grub-2-with-a-ubuntu-live-cd

Thanks in advance!

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Paz
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2 Answers2

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Looks like the Windows update broke grub. It can be fixed using a Ubuntu live CD or USB drive. If you have one you used to install Ubuntu use it, if not - create a new one. There a different ways to proceed. you can see them in this post (different answers for different methods): How can I repair grub?

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Inga B
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Windows has reset the firmware to use its own boot loader rather than rEFInd or GRUB. You should be able to restore it as follows:

  1. Reboot and access the computer's own built-in boot manager. (You probably used this same tool to boot from your Ubuntu installation medium.) This is usually done by hitting Esc or a function key as the computer begins to start, but details vary greatly from one model to another.
  2. The EFI boot manager probably has entries for Windows, Ubuntu, rEFInd, and probably some others. Select the rEFInd or Ubuntu entry.
  3. Once Ubuntu boots, open a Terminal.
  4. Type sudo efibootmgr in the Terminal. You'll see a series of Boot#### entries, a BootOrder line, and a few more things. Note the BootOrder line; it specifies the order in which the computer will attempt to launch the various Boot#### entries. Chances are Windows will be at the top. Note the numbers associated with other boot entries -- particularly rEFInd, if you want to restore it as the default. Note that the Boot#### numbers are hexadecimal, so you might have something like Boot000B as an option.
  5. Type sudo efibootmgr -o a,b,..., where a,b,... is a list of numbers for a new boot order. For instance, sudo efibootmgr -o 5,2,3 would set Boot0005 as the default, Boot0002 to be tried if that fails, followed by Boot0003. Recently, efibootmgr has been insisting of four-digit numbers on some computers, so you might need to use something like sudo efibootmgr -o 0005,0002,0003.
  6. Reboot to test the results.

With any luck, the system will reboot into rEFInd (or GRUB, if you set it as the first entry).

There are other ways to do this. For instance, you can boot an Ubuntu emergency disk rather than boot your normal Ubuntu installation. You'd probably still need to go through the EFI's own boot manager, though, so this won't really gain you anything unless your Ubuntu installation is damaged -- and in that case, you've got a bigger problem on your hands!

Rod Smith
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