View Full Version : Ububtu 12.04 dual boot with windows 8

April 6th, 2013, 04:28 AM

I followed the instructions found here: https://help.ubuntu.com/community/UEFI
Here's the pastbin: http://paste.ubuntu.com/5681729/

Windows 8 is not booting from Grub. Error is:
error: Unknown command `drivemap'
error: Invalid EFI file path

Thanks for the help!

April 6th, 2013, 04:54 AM
Boot-Repair normally adds correct efi chain boot stanza. Grub2 is still creating old BIOS entries that do not work with UEFI.

If Boot-Repair does not add entries to 25_custom you can manually add to 40_custom. Examples in bug report if needed.

grub2's os-prober creates wrong style (BIOS) chain boot entry
type of entry from Boot-Repair that should work.
'Windows UEFI loader'
Type of entry that does not work:
'Windows ...) (on /dev/sdXY)'
Some info in Post #3 on cleaning up menus, if desired.

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

# To clear cache and get new view:
sudo blkid -c /dev/null -o list

This version needs your UUID for the efi partition:

menuentry "Windows bootmgfw.efi " {
search --fs-uuid --no-floppy --set=root 18FE-69D8
chainloader (${root})/EFI/Microsoft/Boot/bootmgfw.efi

/dev/sda2 BC04-26CA vfat SYSTEM

April 6th, 2013, 06:18 AM
Thanks! That did the trick.

For the sake of others:

sudo vim /etc/grub.d/40_custom
edit it to add the ff:

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

To clean grub entries:

sudo vim /etc/default/grub
then add the ff line:


Do this to let grub pick-up the changes

sudo update-grub

Then that's it!

April 6th, 2013, 06:31 AM
@oldfred: By the way, 25_custom was not added to /etc/grub.d/ when I run boot-repair. Might be something with my system set-up or boot-repair