can't boot to Windows 8 after Ubuntu installation

**parminides** · November 18th, 2012

I just bought a a Samsung series 5 Ultra laptop (NP520U4C-A01UB). I was able to disable the secure boot feature in the bios and install Ubuntu 12.04 (as dual boot with Windows eight). Ubuntu works fine, but I can't boot to Windows in Grub. I get the following messages:

Code:

error: unknown command 'drivemap'
error: invalid EFI filepath

Does anyone know how to fix or work around this?

**darkod** · November 18th, 2012

Did you install ubuntu in uefi mode or the older legacy mode?

With uefi boot you actually don't use grub as far as I know. You use the uefi bootloader.

But you have to make sure you install ubuntu in uefi mode, in other words boot the ubuntu cd/usb as uefi device, not as standard bios device.

**oldfred** · November 18th, 2012

If you are booting in UEFI mode, grub-efi has a bug and finds the Windows install, but thinks it still is a BIOS install and creates an incorrect BIOS boot when it should be an efi chain boot entry.

grub-update fails to detect windows bootloader on a uefi system
https://bugs.launchpad.net/ubuntu/+s...b2/+bug/807801
Wrong style chain boot entry
https://bugs.launchpad.net/ubuntu/+s...2/+bug/1024383

You can use Boot-Repair to automatically create the correct entry (or convert from BIOS Ubuntu boot to UEFI boot) or manually add a UEFI chain load entry.

You can just install into your current Ubuntu, use liveCD or USB or download a full repairCD.
Boot Repair -Also handles LVM, GPT, separate /boot and UEFI dual boot.:
https://help.ubuntu.com/community/Boot-Repair
You can repair many boot issues with this or 'Create BootInfo' report (Other Options) & post the link it creates, so we can see your exact configuration and diagnose advanced problems.Install in Ubuntu liveCD or USB or:
Full RepairCD with Boot-Repair (for newer computers)
https://help.ubuntu.com/community/UbuntuSecureRemix

Code:

menuentry "Windows 7 UEFI" {
  search --file --no-floppy --set=root /efi/Microsoft/Boot/bootmgfw.efi
  chainloader (${root})/efi/Microsoft/Boot/bootmgfw.efi
}

So grub does not add the incorrect entries (you can turn on if reconfiguring in the future with other systems).
In /etc/default/grub I added this:
gksudo gedit /etc/default/grub
GRUB_DISABLE_OS_PROBER=true
or turn off executeable bit
sudo chmod a-x /etc/grub.d/30_os-prober

Copy above entry into 40_custom:
gksudo gedit /etc/grub.d/40_custom
Then do:
sudo update-grub

**parminides** · November 19th, 2012

I don't know if I installed in uefi or legacy mode. I did what old fred suggested and it worked. Thank you so much.

Specifically, I booted up to an Ubuntu 12.04.1 liveCD and opened a terminal. Then,

Code:

sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

In boot-repair, I did the recommended repair. When it finished, it gave me the url http://paste.ubuntu.com/1369049/.

There were two new entries in the grub menu,

Code:

Windows UEFI loader
Windows Boot UEFI boot64.efi

which both booted to Windows 8.

The old entries were still in grub,

Code:

Windows 8 (loader) (on /dev/sda2)
Windows Recovery Environment (loader) (on /dev/sda6)

and they still don't work. I can get to the recovery option with the F4 key after powering up, so I'm going to mark the thread solved. But it would be nice to have recovery mode as a grub option if there's an easy fix.