Ubuntu – How to install Ubuntu on an (U)EFI device with existing GPT

Ubuntu's been making slow but steady improvements in its EFI support for the last several versions, so yes, there are differences between 12.04 and 12.10 that could be important. That said, the fact that you got a bunch of dependency errors when you tried to install grub-efi suggests that a more fundamental problem might be the root cause -- perhaps there was a network problem that prevented a string of other packages from installing, for instance. If so, trying again at a later time might correct matters.

That said, on an EFI system, IMHO it's better to use 12.10 than 12.04. This is especially true if it's a recent computer that shipped with Windows 8, since such computers also invariably use Secure Boot, which Ubuntu 12.10 supports but Ubuntu 12.04 doesn't. This isn't the root cause of your problem, though, since 12.04's installation disc won't boot at all if Secure Boot is active; I mention it only for the benefit of others who might read this page.

First, you're missing an EFI System Partition (ESP), which is used to hold EFI boot loaders. Most computers that ship with Windows 8 use /dev/sda2 as the ESP, and your /dev/sda2 is about the right size for that; but your /dev/sda2 holds a Linux filesystem and has no EFI boot loaders. My hunch is therefore that you've accidentally trashed your ESP, rendering the computer unbootable.

Related to the first point, you don't seem to have any EFI boot loader programs on either your hard disk or your SSD.

Your /dev/sda11 is about the right size to be an ESP and does have a FAT filesystem (which an ESP must have), but it's marked as a BIOS Boot Partition.

As a first step, you must create a proper ESP. There are two relatively easy ways to do this:

• Adjust the type code on /dev/sda11. In GParted, you can do this by removing the "bios_grub flag" and setting the "boot flag." In gdisk, you'd do this by setting the type code to EF00.
• Adjust the type code on /dev/sda2 and make it FAT32. In GParted, you'd do this by setting a "boot flag" and creating a FAT32 filesystem on it. In gdisk, you'd set the type code to EF00 and then use the separate mkdosfs utility to create a FAT32 filesystem on the partition.

Once that's done, you can begin recovery. In theory, you can use Boot Repair to do the task, at least for Linux; but as it appears it led you down the wrong path before, you might want to do something different:

1. Download and prepare a bootable USB flash drive or CD-R version of my rEFInd boot manager.
2. Boot with rEFInd. It should show you at least one option for booting Linux.
3. Boot to Linux.
4. Open a Terminal window.
5. Edit your /etc/fstab file to mount your ESP (/dev/sda2 or /dev/sda11) to /boot/efi.
6. Type sudo mount -a.
7. Type df -h and ensure that there's a line for /boot/efi, showing the correct partition mounted. If not, go back to step #5.
8. Download and install the Debian-package version of rEFInd.

At this point, rEFInd should enable you to boot Linux. Your Windows installation will remain unbootable, though, until you run a Windows recovery tool. You should be able to download something from Microsoft's site to repair the Windows boot loader, but I don't happen to have a URL or instructions handy. I recommend you ask on a Windows site if you have problems with this part of the task. Note that after you're done, the Windows boot loader will be set as the default, so you'll need to change that. You can either follow steps 2 and 10-11 in this procedure or use the USB flash drive to boot to Linux and then re-install rEFInd from there. Alternatively, you could repair Windows before you repair Linux, but you'll need to fix the ESP before you do either OS-specific repair.