As soon as we turn on the computer, it immediately starts running a miniature operating system, which we know as BIOS. It deals with testing devices, memory, loading operating systems, and distributing hardware resources. Many of the features of this set of programs (usually about 256-512 KB in size) allow you to support older operating systems like MS-DOS, giving them many features. Since the days of the PC/AT-8086, the BIOS has changed very little, and by the time the first Pentiums were launched, its development had almost stopped. Actually, there was nothing to change in it except dual BIOS, support for network tools and the ability to flash the firmware. But there were a lot of disadvantages: initial entry into the real processor mode, 16-bit addressing and 1 MB of available memory, the inability to have a “repair” console. And, of course, the eternal problem of support hard drives. Even now, disks up to 2.2 TB are guaranteed to be supported, no more.

Back in 2005, Intel decided to change the BIOS to EFI/UEFI (Unified Extensible Firmware Interface). The EFI system is a more advanced base operating system. UEFI has been working on some Unix and Windows platforms for a long time, but a mass transition has not yet occurred, despite good intentions. And they are like this:

• Availability of the notorious console for repairing system parameters and installing the OS;
• The EFI partition makes it possible to perform some actions without loading the OS (watching movies, playing music);
• Internet access and therefore availability installed drivers network, TCP/IP stack, etc.);
• Presence of graphic mode and user scripts;
• Support for gigantic disks;
• UEFI storage on new format partitions (GPT);
• Full support for all equipment from the moment of launch.

UEFI can use a general-purpose execution engine like the JVM to run hardware-independent code, which opens up enormous possibilities for creating bootable software.

There is also criticism of this technology. In particular, its implementation may lead to cutting off new players from the operating system market: for this purpose there will always be some technological loophole in the code. Like, for example, the inability to boot Windows 98 from modern BIOSes. But what’s worse is that you’ll have to forget about the millions of MS-DOS programs and other systems that relied on BIOS functions to operate. Perhaps they will still be emulated, but there are doubts about this. And among them there are probably important programs that there will be no one to rewrite. However, all these issues can be resolved – at least through virtual operating systems. But what is certain is that new types of viruses will appear, and we will be able to see this quite soon.

When we install Windows to empty (unlabeled) HDD or formatted partition in the usual way - using installation media, we don’t need to bother about creating EFI partitioning operating system. All necessary partitions, in particular the boot EFI, are created automatically if the computer is running in BIOS UEFI mode. But if you need to install Windows in a different way.

And to another hard drive with its own independent bootloader, if there is a question about restoring the system after deletion hard drive with a boot partition, in such non-standard situations manual work will be required.

Windows does not install on a second GPT disk connected to the computer with its own EFI-structure. During a normal installation from installation media, the bootloader of the second system is registered on the existing one. EFI-partition – the one located on the first disk.

What makes the second Windows vulnerable is that it will not be able to exist independently if the bootloader of the first system is damaged. Or if the first hard drive fails or is simply disconnected. To second Windows had its own independent EFI- markup, during its installation you need to make the first system invisible - disable its media in BIOS settings, if possible, or in hardware. This is not always convenient, and sometimes even impossible in the case of laptops.

A second Windows with its own independent boot loader can be installed by those running in the environment current system programs like or WinToHDD. But they will require you to specify the bootloader EFI-chapter.

It's very easy to create one on an empty hard drive.

1. Create an EFI partition on an empty hard drive in the command line

So, we have a medium initialized as GPT without markup and data.

Let's launch command line.

Be sure to do this on behalf of the administrator.

We enter one by one:

diskpart lis disk sel disk 1 (instead of 1, indicate the number under which the hard drive you need is listed above) creat par efi size=100 format fs=FAT32

lis disk sel disk 1 (instead of 1 indicates the number under which the hard drive you need is listed above) creat par efi size = 100 format fs = FAT32

In the disk management utility we see that on the second hard drive appeared EFI-section on 100 MB. Now we can create a regular partition to indicate it to programs like or WinToHDD as system partition WITH.

2. Creating an EFI partition on an empty hard drive using the Bootice utility

Who doesn't like the command line to create EFI-to mark up empty media, you can use the utility with graphical interface. It is free and can be downloaded from any software portal on the Internet. In the main window, select the second hard one. Click.

Then - “Re-Partitioning”.

First of all, check the GPT box in the “Partition table type” column. Then check the box “Create ESP partition”. And at the top in the “Settings” column we remove all “Size” values except the last one. Click "Ok".

As a result, we get a disk layout with EFI-section on 128 MB and a partition that contains the rest of the disk space.

But what if the hard drive is not empty? If it has a structure and stored user data. Or we want to restore Windows that has lost its boot boot EFI-partition after failure or disconnection of the hard drive on which its bootloader previously existed. And there are solutions for this case. To restore a system without a bootloader, we naturally need an environment to perform certain operations. In one case, regular Windows installation media will do. In another case, we will work with a disk space manager, so we will need a functional and reliable LiveDisk WinPE. One of these is Sagittarius LiveDisk. Image download site - Sergeistrelec.Ru.

Note: The following operations cannot be performed on disks dynamic type. The disk of a Windows mirror that is left without a bootloader must first be converted to a basic type. This can only be done through third-party means.

3. Creating an EFI partition at the end of Windows

So, we have, for example, a second Windows that has lost EFI-bootloader after the failure of the disk with the first system.

How to launch it? The simplest and quick way- create EFI-partition at the end of the system partition and recreate the bootloader. You don't need anything more than a command line to do this. Boot from the Windows installation media, immediately press Shift + F10. This combination will launch the command prompt. If we use LiveDisk Sagittarius, we start, accordingly, from it.

And already on board we use the command line.

In it we enter:

diskpart lis vol sel vol 1 (instead of 1, indicate the number under which your partition with the system is listed above) shrink desired=100 creat par efi format fs=FAT32

Here is the specified section compressed to 100 MB and in the vacant place was created EFI-chapter.

Now we can recreate the bootloader.

On the command line, exit :

That's it - Windows functionality has been restored.

4. Creating an EFI partition before Windows

The boot partition usually exists at the beginning of the disk, before the system partition. It doesn't have to be this way, but it's done to speed things up. Windows startup. To make UEFI find the bootloader faster. On an SSD, such optimization is unlikely to be noticeable, but in the case of an HDD, you can compete even for a fraction of performance.

On board LiveDisk Sagittarius let's launch. Click on the system partition, and on the side operations panel click “Resize”.

Pull the slider on the map a little to the right so that in the column below “Unallocated space in front” several MB. Next, instead of the drawn number, we enter 105 . To make it work 105 MB. Click "Ok".

As a result, the program will release the correct amount of disk space, in our case 102.01 MB. And it will leave a small tail at the back of the section. Click.

We confirm.

Now let's launch the command line. And we create EFI-section exactly the same as described in paragraph 1 of the article.

Here EFI-the section has been created.

All that remains is to recreate the bootloader, as described at the end of paragraph 3 of the article.

Updated: October 2013

Purpose: Windows 8, Windows 8.1, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2

This section describes how to configure disk partitions, including hard disks(HDD), solid state drives(SSD) and other drives for BIOS-based Unified EFI Interface (UEFI) computers.

In this section

Partition configurations

This section describes the default partition configuration and the recommended partition configuration.

Default configuration: environment tools section Windows recovery, system partition, MSR partition and Windows partition

The default Windows installation configuration includes the Windows Recovery Environment Tools partition, the System partition, the MSR partition, and the Windows partition. This configuration is shown in the following diagram. This configuration allows you to enable BitLocker drive encryption and store the Windows Recovery Environment on a hidden system partition.

Using this configuration, utilities such as Encryption can be added to a custom Windows installation Windows disk BitLocker and Windows Recovery Environment.

Recommended configuration: Windows Recovery Environment partition, system partition, MSR partition, Windows partition, and recovery image partition

The recommended configuration includes: Windows Recovery Environment partition, system partition, MSR partition, Windows partition, and recovery image partition. This configuration is shown in the following figure.

The Windows Recovery Environment Tools partition and the System partition are added before the Windows partition is added. The last partition to be added is the recovery image. This partition order will help keep the system partition and the Windows Recovery Environment partition safe during actions such as deleting the recovery image partition or resizing the Windows partition.

How to repair EFI bootloader of Windows 7 and Windows 10?

In this article we will try to repair the EFI boot loader for Windows 7/8/10. We already looked at it a little earlier. Now let me immediately note that bootloader damage in our case is most often (among other things) caused by:

• installing a second operating system
• incorrect system recovery operations (or unsuccessful completion)
• deleting some data from hidden sections
• bad sectors
• the action of malware.

Using the tools presented, you can try to restore the EFI bootloader, which refuses to boot the system due to a missing or broken configuration file at:

Hidden drive:\EFI\Microsoft\Boot\BCD

Here, by the way, is its approximate content from:

To be clear...

The partition structure in a GPT table on Windows booted in UEFI mode most often looks like this:

• EFI - ESP (Extensible Firmware Interface) partition - partition where software with drivers to boot Windows;
• MSR – also known as Microsoft Reserved – partition reserved during Windows installation; it may well not be on your machine
• The primary partition is the volume where system files are stored: the registry, services, system utilities, settings files, etc.

Windows 10 also adds a Recovery disk here. By default (i.e. when Windows installation to an UNFORMATTED disk), the first two partitions have a clear volume. And therefore, if necessary, it is easy to isolate them, focusing only on the sizes of both. In Windows 7, for example, this is 100 MB and 128 MB, respectively. And that being said, typical configuration. Some computer manufacturers create partitions at their own discretion, for example, by putting the Windows PE recovery environment in a file winre.wim. If you find such a file, know that it contains a system recovery image from the manufacturer. An EFI partition is required on GPT disks with UEFI support. When the computer turns on, the UEFI environment loads the boot loader ( EFI\Microsoft\Boot\bootmgfw.efi) from the EFI (ESP) partition, giving it control over loading Windows itself. No section - no download.

The MSR partition on the disk is created to facilitate the overview of partitions and is used for system operations (such as converting a disk from simple to dynamic). This is a spare partition that Windows never assigns identification marks to. And it does not contain user data. In Windows 10, the MSR partition size is 16 MB (in Windows 8 – 128 MB), the file system type is NTFS.

Windows Boot Configuration Data

You may be notified that the file at the above address EFI\Microsoft\Boot\BCD is damaged blue screen BSOD death with the following error:

The boot configuration data for your PC is missing or contains errors. File:\EFI\Microsoft\Boot\BCD Error code: 0xc0000***

This means that the data in the Boot Configuration Data file does not recognize your Windows boot loader configuration. However, users familiar with the bootloader recovery utility in MFT bcdedit.exe, this time she won’t help out. When trying to launch it, the user will see something unusual:

The boot configuration data store could not be found. The requested system device cannot be found

Like, neither the data nor the device itself exists. There is only one reason: since the configuration of the BCD bootloader in UEFI boot mode lies in a special EFI section:

efi partition in Windows 7

efi partition in Windows 10

...then our utility simply does not see it. Those. The bootloader itself does not see, or even the entire partition. In general, traditional recovery tools created for such a case do not help:

Is yours also misspelled?

How to restore the Windows 10 EFI bootloader: straight to the point.

• select the boot device by calling up the quick boot menu using the keys in zone F or

• load from ;
• exit to the command line by holding Shift + F10 after the window appears Windows installation
• as in the previous mode, we need to decide on the list of computer partitions. Next, I assume that the hard drive is installed in a single copy:

diskpart list volume

• We find the EFI partition. Its size, again, is small (100 MB in W7 and W10), and it has file system FAT32:

I have EFI - this is the unnamed Volume 3

• by default it is hidden, which means it does not have a letter. For further work we will need it. So let's assign a letter right now:

select volume * assign letter Y: exit

After closing the program, go to this section:

cd /d Y:\EFI\Microsoft\Boot\

There is a slight digression here. This path exists by default, and there is no reason for the console to deny you access to the specified folder. If an error appears, see paragraph Possible mistakes or go straight to the next part How to restore the EFI bootloader of Windows 7/10: rebuilding the EFI.

I got the Access Denied error right away

• we recreate the boot sector of the partition of the same name:

bootrec/fixboot

• using the utility bcdedit.exe let's create the storage again, copying the boot files from the system folder:

bcdboot C:\Windows /l ru-ru /s k: /f ALL

/f ALL – copies boot files (both UEFI and BIOS modes) for possible support for booting to EFI and BIOS;

/l ru– ru – will indicate the language locale of the system that will be used, i.e. into Russian. If everything goes without errors, skip the paragraph.

• execute the following commands sequentially:

bootrec /scanos bootrec /rebuildbcd

We reboot into Windows 10 on the hard drive and check.

Possible mistakes

The administrator may encounter some errors here. Among them, the most frequently appearing are:

• BFSVC Error: Cannot open the BCD template store. status – –
  you need to check the entered commands and the path to storing system Windows files; sometimes the error appears due to incorrectly specifying the language locale;
• BFSVC Error: Error copying boot files from Last Error = 0x570 – the error is a consequence of the very phenomenon that Windows does not boot. It is likely that bad sectors appeared not only in the EFI boot partition, but also on the system disk; run the hard drive with the utility chkdsk.exe immediately from the console with the command

chkdsk from: /a

where c is the disk with the system

• Access is denied - there are many reasons for this: from the presence of bad sectors to an incorrectly set boot mode (Legacy is used instead of UEFI; only UEFI is needed) from a flash drive. However. UEFI would not be UEFI if everything went so smoothly: the fact that the EFI partition does not allow access to its files is more a pattern than an exception. So, if you are denied access, I advise you to simply delete the EFI partition itself first (we don't need that anymore), recreate it with the only directory necessary for it to work, and then rely on the repair bootrec to allow it to complete work. So, if the need arises, we continue to work from the moment the team fails

bootrec /fixboot How to restore the EFI bootloader of Windows 7/10: rebuild the EFI.

The most important thing here is not to miss the partition/s and do not delete the one in which they are stored. Windows data and your information. So once bootrec.exe I couldn’t get into the section we needed, so we’re removing the section. To do this, we will need to return to diskpart.exe, again decide on the partitions and select the one with 100 MB. Returning to the repair console:

Cd/dx:

And we start again:

Diskpart select disk 0 list partition select partition 2

remove it:

Delete partition override

you can check the result:

List partition

We have some unallocated space left, in which we re-create the just deleted partition:

Create partition efi size=100 list partition select partition 1 format quick fs=fat32 label="System"

But when I tried to assign the previously used letter Y, the console refused (it had to be restarted). I'll give the partition the letter Z :

Assign letter=Z exit

Let's prepare the way for bootrec.

• create a download folder:

mkdir Z:\EFI\Microsoft\Boot

• copy the files from the EFI environment there from the folder installed Windows(C is the drive letter with Windows system files):

xcopy /s C:\Windows\Boot\EFI\*.* Z:\EFI\Microsoft\Boot

• let bootrec from your flash drive check the disks for system files Windows:

bootrec /scanos

They won’t go anywhere unless you accidentally delete them or they fall into the bad sector zone. It remains...

• ... force you to write the “correct” BCD file and other “configs”:

bootrec /rebuildbcd

Turn off the computer, remove the flash drive and turn on the machine. We wait emergence of Windows. Let it boot to the Desktop and check if everything is in place.

The error appears again...

Do not worry. If you delved into the process and entered all commands consciously and correctly, the situation has most likely already been corrected. You just need to take into account the peculiarities of the unique security filters adopted for the UEFI mode, and not confuse the drive letters. They can be completed by following these steps:

• Wake up BIOS:
  – remove the side cover of the computer or the bottom of the laptop
  – disconnect the hard drive (by disconnecting both cables on the “stationary” or by removing them from the connectors on the laptop)
  – turn on the machine, waiting for the boot error;
  – after turning off the computer, reconnect the hard drive and again, turning on the computer, check;
• check the UEFI menu of the computer board for the correct order of boot partitions; the first one should be, as you understand, EFI;
• make sure that the Boot label is only next to the EFI partition, and nothing else. Unfortunately, it is not possible to check and correct the situation from Windows PE. And for this you will have to use additional tools as bootable flash drive. Do this using any convenient option from the article Bootable disk label: how to add or remove?

That's all I wanted to say. Good luck.

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