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Can I re-enable Secure Boot, Fast Start-up, or Bitlocker on Win10 on a Dell Inspiron 15 3567 Dual boot (Grub default) Ubuntu18.4 Windows10 system? What are risks or implications.

mako34
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1 Answers1

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Secure Boot

  1. Ubuntu installs differently when secure boot is disabled.

When Ubuntu is installed in the UEFI mode with secure boot disabled, it installs \EFI\ubuntu\grubx64.efi.

When Ubuntu is installed in the UEFI mode with secure boot enabled, it installs \EFI\ubuntu\shimx64.efi.

If you enable secure boot after installing Ubuntu, the Ubuntu will not not boot if the shimx64.efi does not exist.

The difference between shimx64.efi and grubx64.efi is that shimx64 is the actual Microsoft signed binary that works with Secure Boot enabled while grubx64 is the normal grub binary (Not signed).

  1. Some third party device drivers can only be installed when secure boot is disabled.

The third party device drivers may not load and thus, some specific devices will not work.

See Is re-enabling Secure Boot in UEFI secure? for more.

Fast Start-up

Fast Start-Up or fast-boot can mean two things.

I assume this is the option in Windows 10.

This is not the UEFI option that skips the boot setup and boot device select menu when the computer boots.

Fast Start-up does not shut down Windows properly, and puts it in a hibernate state when Windows is shut down. This means all the partitions that are accessible by Windows (C:\, D:\, etc) are not properly shut down. Ubuntu will not be able access these drives properly in this state. In particular, you will not be able write files, including copy, move, etc., to these partitions when you use Ubuntu. This will be an issue if you have a common partition that you share between Windows and Ubuntu.

See Unable to mount Windows (NTFS) filesystem due to hibernation this answer for more explanation.

Bitlocker

Enabling Bitlocker in Windows will also make the Windows partition inaccessible from Ubuntu.

There may be ways to get around it. See Use (Windows) BitLocker-encrypted drive on Ubuntu 14.04 LTS

Disclaimer: I have not tried any of these things. So, there may be other consequences of enabling Secure Boot, Fast Start-up, and Bitlocker I am unaware of. Use at your own risk.

user68186
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