I have an Ubuntu USB stick and would like to be able to boot it from my UEFI laptop too (in addition to older BIOS devices). Currently, it is not shown in the list of bootable devices unless I enable the Compatibility Support Module. What do I have to change to make this work without?

I think I should add some kind of EFI folder into the boot partition, but I have no idea.

Edit: Ubuntu freezes on the startup screen and my Arch USB stick "can't access tty: job control turned off" so using CSM is not an option for me.

  • Is this a full install of Ubuntu on the USB or a Live USB that can be used to install Ubuntu on the internal drive? – user68186 Mar 12 '18 at 19:05
  • It is both a full, persistent install – piegames Mar 12 '18 at 19:08
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    See askubuntu.com/questions/559007/… The answer has a part about existing USB. – user68186 Mar 12 '18 at 19:11
  • There may be useful tips at the following link, help.ubuntu.com/community/Installation/UEFI-and-BIOS – sudodus Mar 12 '18 at 19:16
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    @user68186 The linked answer solved it for me, thanks. TL;DR: Create an EFI partition, mount it as /boot/efi and reinstall GRUB with the efi parameter. That's it – piegames Mar 17 '18 at 17:07

Mkusb will make a Persistent drive that works on BIOS and UEFI. You can confirm this on your machine before proceeding.

It is easy to change a mkusb Persistent USB to a Full install USB that also works on BIOS and UEFI.

  • Use mkusb to make a Live system on a USB (2GB or larger).
  • Use mkusb to make a Persistent system on a USB 16GB or larger, using default settings with ~12GB persistence.
  • Remove HDD before proceeding, (optional but recommended).
  • Insert both USB drives.
  • Boot Installer drive, select Install.
  • Select Something else.
  • Select sdb5, (the target drive), and click Change.
  • Select Use as: ext4, Format, Mount point /.
  • Don't touch any other partitions.
  • Select sdb5 for boot loader installation.
  • Complete installation.
  • Cut grub.cfg from sdb5/boot/grub and paste to sdb3/boot/grub, overwriting the existing grub.cfg file.
  • Delete sdb4, the ISO9660 partition and expand sdb5 into the recovered space.
  • Boot the target drive and run sudo update-grub, (optional).
  • How does this work with existing USB sticks? – piegames Mar 17 '18 at 17:04
  • I don't know of a way to convert an existing BIOS only USB stick to a UEFI stick, partitioning may not be compatible. I think you can clone the existing OS partition to sdb5 of the new drive using gparted and then overwrite the grub.cfg on sdb2 with the existing. see askubuntu.com/questions/1013917/… , similar should also work for an existing Persistent stick. – C.S.Cameron Mar 18 '18 at 16:36
  • However with an existing Persistent stick all you need to do is copy the existing casper-rw file or partition to the new mkusb BIOS/UEFI drive. – C.S.Cameron Mar 18 '18 at 18:19

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