View Full Version : [ubuntu] Handy tip if you break your BCD while installing an Ubuntu/Win8 dual boot

January 31st, 2013, 12:27 AM
Nothing particularly exciting here, but I didn't find anyone else suggesting this during the 4 hours I just spent messing about, so I thought I'd post it in case it avoids someone else paying the same price for their stupidity that I did :p

1] I initially used EasyBCD to try to set up Ubuntu 12.10 on my UEFI laptop (asus s200e), then decided to go the grub route instead

2] Unfortunately in the meantime I had somehow deleted the Windows options from the Windows bootloader

3] As a result, after installing 12.10 alongside Windows, and running boot-repair to get the Windows bootloader option back again, I was then no longer able to launch windows or any recovery options

(I tried using a friend's Win8 machine to generate a recovery USB but that didn't work for some reason)

4] However I was able to recover by doing the following:
4.1] In 12.10, mount the windows partition (ie c:\), which I found by trial and error (sda4 for me)
4.2] I found a handy EasyBCD backups in my Documents folder
4.3] Also grabbed my broken BCD file from sda1, path EFI/Microsoft/Boot/BCD
4.4] Installed EasyBCD to my work (win7) machine, and opened that BCD file File>"Select BCD Store" (very important!)
4.5] Restored from backup, saved the BCD
4.6] Copied the BCD back onto the laptop running 12.10, to the path from where I found it (EFI/Microsoft/Boot)

and rebooted!

5] Obviously I got lucky that I had a backup. However I could have easily have fixed it without the backup had I known what the parameters were ... I initially tried just creating a Windows 8 partition in my saved BCD file, but it didn't work, I got an error trying to access the bootloader path of "\windows\system32\winload.exe"

In practice the correct parameters are (the GUIDs don't matter, they get auto-generated):

Windows Boot Manager
identifier {9dea862c-5cdd-4e70-acc1-f32b344d4795}
device unknown
path \EFI\Microsoft\Boot\bootmgfw.efi
description Windows Boot Manager
locale en-US
inherit {7ea2e1ac-2e61-4728-aaa3-896d9d0a9f0e}
default {9d29de2f-314c-11e2-8999-8bfd80b6b764}
resumeobject {9d29de2e-314c-11e2-8999-8bfd80b6b764}
displayorder {9d29de2f-314c-11e2-8999-8bfd80b6b764}
toolsdisplayorder {b2721d73-1db4-4c62-bf78-c548a880142d}
timeout 30
displaybootmenu Yes

Windows Boot Loader
identifier {9d29de2f-314c-11e2-8999-8bfd80b6b764}
device unknown
path \Windows\system32\winload.efi
description Windows 8
locale en-US
inherit {6efb52bf-1766-41db-a6b3-0ee5eff72bd7}
recoverysequence {9d29de31-314c-11e2-8999-8bfd80b6b764}
recoveryenabled Yes
isolatedcontext Yes
allowedinmemorysettings 0x15000075
osdevice unknown
systemroot \Windows
resumeobject {9d29de2e-314c-11e2-8999-8bfd80b6b764}
nx OptIn
bootmenupolicy Standard

You can easily set parameters from EasyBCD by going to "useful utilities", select power console and then running commands like:

"bcdedit.exe /store <path/to>/BCD" - lists the current settings

"bcdedit.exe /store <path/to>/BCD /set path <VALUE>" - to set the path, eg after adding a new "Windows 7/8" entry use

"bcdedit.exe /store <path/to>/BCD /set path \windows\system32\winload.efi"

(For some reason I found I had to close the main EasyBCD GUI before doing any "/set"s, I then opened it up again and reloaded to double check my changes had taken)

Hope nobody gets themselves into the state I did, but that this helps if they do!

January 31st, 2013, 12:51 AM
Making a Windows 8 repair is different than the Windows 7.

Windows 8 UEFI repair USB must be FAT32

Was it the backups from EasyBCD or Boot-Repair that you used?

Older versions of EasyBCD did not work with UEFI.

February 1st, 2013, 04:48 PM
Making a Windows 8 repair is different than the Windows 7.


Was it the backups from EasyBCD or Boot-Repair that you used?

Older versions of EasyBCD did not work with UEFI.

Sorry if my ramble was unclear!

1] I downloaded the latest version of EasyBCD onto Windows 7 (I didn't have any win8 machines)

2] I then used an EasyBCD backup from my "dead" win8 dual boot (by accessing the partiton from linux), which generated a working BCD file


3] I could equally have created a loader entry with EasyBCD - this will not immediately work with Win8, but you can then use bcdedit as described to set the parameters that EasyBCD gets wrong

Point [3] is useful in case you don't get lucky and have a backup

I didn't use any win7 or win8 recovery infrastructure