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Several tutorials and how-to's on ask ubuntu re uefi booting refer to efibootmgr as being capable of controlling a uefi boot. In all cases I have seen the tutorial asks you to

modprobe efivars

How can this be done when the kernel module efivars.ko does not exist in any Ubuntu kernel that I can find. If you doubt me do these two things, firstly run the command

sudo modprobe -l | grep efivars

You will get no results. Next go to packages.ubuntu.com and enter the search term efivars.ko in 'search the contents of packages'. Again you will get no results.

Debian have kernels with this module in it and so to Arch. Ubuntu however do not. Or if they do they conceal them remarkably effectively.

Am I missing something - it is not unknown!

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1 Answer

A cursory examination of an Ubuntu 12.10 installation I've got suggests that the efivars kernel module is now built into the kernel rather than installed as a module. Most notably, here's an entry from /usr/src/linux-headers-3.5.0-19-generic/.config:

CONFIG_EFI_VARS=y

This indicates that the support is built into the kernel. The effect of this module is to create the /sys/firmware/efi directory, and it's present on the system in question.

When a module is built into the kernel, you don't need to load it, so you can ignore any instruction to do so, so long as you're sure the module is built into the kernel. In the case of efivars, just check for the presence of /sys/firmware/efi.

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