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Главная » Статьи » Системное администрирование » Об ОС Windows

How to repair the EFI Bootloader in Windows 8

How to repair the EFI Bootloader in Windows 8

 
 

Are you hungry right now?

Yes?

Then this analogy will make sense because I’m going to reference my favorite sandwich of all time: A Prosciutto, Soppressata, Italian hero with Banana peppers, fresh mozzarella and oregano.

Think of EFI like the palatable center of my Italian sandwich.  Your system board is the bottom part of the roll and the OS, Windows 8, is the top half.

EFI, short for Extensible Firmware Interface, forms a delicious layer of protection against pernicious badware (Rootkits anyone?) by requiring valid digital signatures from the bootloader.  It also replaces the antiquated Master Boot Record (MBR) with the modern GUID Partition Table (GPT) so your computer can stop ignoring hard disks larger than 2TB.

The bootloader is the program that “kicks off the show”.

After the PC finishes a sequence of hardware health checks known as a Power On Self Test (POST), the bootloader enters the scene and galvanizes the OS.

But what happens when the computer fails to boot?  What do we do when the bootloader becomes damaged and the OS refuses to obey the ordinance to start?

The example I adduced above is a good reason to have a Windows 8 USB recovery drive on hand.  If you don’t have that, see if you can boot to the original Windows 8 DVD that came with the system.  If you can’t find that either then take a breath, stay composed and get Easy Recovery Essentials.

EasyRE is a great utility because it automatically detects and repairs common problems with the bootloader, BOOTMGR and winload.exe.  The only draw back is that it costs between $20 and $40 depending on your flavorof Windows.  You can view the 4 minute Youtube demo to see if it’s worth it but first I want to show you something that might fix your problem for free…

The fix

Start up your dilapidated computer with the USB or DVD Windows 8 recovery media in the system.  You want to get to the Advanced options screen so you can open the beloved command prompt.

When the computer boots off the recovery media, pick the Troubleshoot option

Windows 8 Advanced Startup Troubleshoot

Then choose Advanced Options

Windows 8 Advanced Options

and head on over to the Command Prompt.

Windows 8 Advanced options Command Prompt

The computer should reboot and then ask you for the account.  Click your account to continue.

Windows 8 Command Prompt Account

Then login to get started

Windows 8 Command Prompt Account Login

We’re going to use the built in partitioning tool called diskpart to confirm that:

  1. We have all the right partitions
  2. EFI partition is formatted correctly.

In the black screen that looks like a dark abyss, type:

diskpart

and enter this command:

sel disk 0

Now that the first disk is selected we need to view all the partitions

list vol

Windows 8 diskpart

Verify that the EFI partition is using the FAT32 file system then select the volume and assign a drive letter to it.

Since i’m using Windows 8 from a VirtualBox image you won’t see the FAT32 partition on the screenshot above; but on yours you can select it by noting the Volume Number.

1. Assign the Drive Letter

Let’s say your EFI partition is on Volume 3, the next thing you would type is:

sel vol 3

Then assign an arbitrary drive letter to the parition.  Let’s use v.

assign letter=v:

You should see a message saying: DiskPart successfully assigned the drive letter or mount point.

Exit the diskpart tool by typing:

exit

You should still be in the command prompt but outside of the DISKPART> prompt.

2. Repair the Boot Record

We need to repair the boot record.  We can pull that off like so:

cd /d v:\EFI\Microsoft\Boot\
bootrec /fixboot

The CD command tells the command line interpreter to change the directory to the volume label that has the EFI boot record.

Then the bootrec /fixboot command attempts to repair the selected volume.

Alright, still with me?

3. Rebuild the BCD store

Now we need to recreate the Boot Configuration Data (BCD) store, so let’s backup the existing store first

Type:

ren BCD BCD.old

Now that we backed it up, let’s recreate the BCD store:

bcdboot c:\Windows /l en-us /s v: /f ALL

BCDBoot is little tool that lets you manage the system partition files.  In plain english, this command says:

Hey Windows, I’m going to use C:\Windows as the source for copying all my boot-environment files and I’m going to use the English locale and select the volume letter that begins with v:  

The /f ALL thingy updates all the BIOS settings.

Now remove the recovery media and reboot and you should be all set.

 
 


Источник: http://www.fixedbyvonnie.com/2013/06/how-to-create-a-windows-8-recovery-usb-flash-drive-in-5-minutes/
Категория: Об ОС Windows | Добавил: admin (26.12.2014)
Просмотров: 479 | Теги: UEFI, USB, recovery, BIOS, efi, Bootloader, flash | Рейтинг: 0.0/0
Всего комментариев: 0
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