I have Windows 10 installed in my laptop and i'd like to install Ubuntu 18.04 too. I just create a bootable USB and install Ubuntu (with the option 'Install alongside Windows 10')? Is there anything I need to do with Secure Boot? As i see in System Information my BIOS Mode is in Legacy and secure boot is unsupported. Do I proceed with the installation or do I have to change any values from BIOS or anywhere else?

marked as duplicate by mikewhatever, karel, Fabby, Eric Carvalho, David Foerster May 15 '18 at 8:44

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No, you don't have to do anything related to secure boot in your BIOS, thanks to shimx64.efi and grubx64.efi EFI binaries, one for Secure boot enabled and another one for not.

To read more details about the topic : What is the difference between grubx64 and shimx64?

Or here's the best answer of the above question.

Typically, EFI/ubuntu/grubx64.efi on the EFI System Partition (ESP) is the GRUB binary, and EFI/ubuntu/shimx64.efi is the binary for shim. The latter is a relatively simple program that provides a way to boot on a computer with Secure Boot active. On such a computer, an unsigned version of GRUB won't launch, and signing GRUB with Microsoft's keys is impossible, so shim bridges the gap and adds its own security tools that parallel those of Secure Boot. In practice, shim registers itself with the firmware and then launches a program called grubx64.efi in the directory from which it was launched, so on a computer without Secure Boot (such as a Mac), launching shimx64.efi is just like launching grubx64.efi. On a computer with Secure Boot active, launching shimx64.efi should result in GRUB starting up, whereas launching grubx64.efi directly probably won't work.

Note that there's some ambiguity possible. In particular, if you want to use a boot manager or boot loader other than GRUB in a Secure Boot environment with shim, you must call that program grubx64.efi, even though it's not GRUB. Thus, if you were to install rEFInd on a Secure Boot-enabled computer, grubx64.efi could be the rEFInd binary. This binary would probably not reside in EFI/ubuntu, though; both it and a shim binary would probably go in EFI/refind. Also, as you've got a Mac (which doesn't support Secure Boot), there's no need to install rEFInd in this way; it makes much more sense to install rEFInd as EFI/refind/refind_x64.efi (its default location and name).

Note that the rEFInd documentation includes a whole page on Secure Boot. Chances are you won't benefit from reading it, user190735, since you're using a Mac. I mention it only in case some other reader comes along who's trying to use rEFInd in conjunction with Secure Boot.

  • Long story short, i'm good to go? – Georgio3 May 11 '18 at 21:12
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    ..Absolutely! :) – Vishesh Gautam May 11 '18 at 21:13
  • Happy to help, would you mind to mark my answer as 'Solution' or vote it up?. – Vishesh Gautam May 11 '18 at 21:15
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    Did it, my upvote is not counted because i'm a new member. But i've marked it as 'Solution'. – Georgio3 May 11 '18 at 21:16

You can go ahead, even if secure boot was enabled Ubuntu's installer will walk you through some steps to disable it.

  • So everything's ok with it and BIOS Mode which is in 'Legacy'? – Georgio3 May 11 '18 at 21:06
  • Yes, however it is always wise to do a backup of Windows before attempting this. I had my windows partition erased a while ago while trying to dual boot with Ubuntu 12.04 because of a corrupt usb drive. – monty47 May 11 '18 at 21:14

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