BCDBOOT what is this ?

BCDBOOT

BCDboot is a tool used to quickly set up a system partition, or to repair the
boot environment located on the system partition. The system partition is set
up by copying a small set of boot environment files from an installed
Windows® image. BCDboot also creates a Boot Configuration Data (BCD)
store on the system partition with a new boot entry that enables you to boot to
the installed Windows image.

You can run BCDboot from Windows® PE. For information on Windows PE,
see Windows PE Walkthroughs.

BCDboot is included with Windows® 7 and Windows Server® 2008 R2 in the
%WINDIR%\System32 folder. BCDboot is also available in the Windows
OEM Preinstallation Kit (OPK) and Windows Automated Installation Kit
(AIK) under the %Program Files%\\Tools directory, where
is either Windows OPK or Windows AIK.
BCDboot copies a set of boot environment files from a Windows image that is
already on the computer. BCDboot can copy boot environment files from
images of Windows Vista®, Windows Server® 2008, Windows 7, or Windows
Server 2008 R2. For information on applying a Windows image to a system, see
Capture and Apply Windows Images.

BCDboot uses the file: %WINDIR%\System32\Config\BCD-Template file to
create a new BCD store and initialize the BCD boot-environment files on the
system partition. Specific BCD settings can be defined in the BCD-Template
file. The tool also copies the most recent versions of boot-environment files

from the operating system image %WINDIR%\boot folder and
%WINDIR%\System32 folder to the system partition.
BCDboot copies files to the default system partition identified by the firmware.
You can create this partition by using a partitioning tool such as DiskPart. You
do not have to assign a drive letter to this partition for BCDboot to locate it.
For more information, see the DiskPart Help from the command line, or
Diskpart Command line syntax.

On BIOS-based systems, the system partition is the active partition on disks
using the Master Boot Record (MBR) disk format. BCDboot creates the \Boot
directory on the system partition and copies all required boot-environment files
to this directory.

On Unified Extensible Firmware Interface (UEFI)-based systems, the EFI
system partition is the system partition on disks using the GUID Partition Table
(GPT) disk format. BCDboot creates the \Efi\Microsoft\Boot directory and
copies all required boot-environment files to this directory.
BCDboot can update an existing boot environment to the system partition.
Newer file versions from the Windows image will be copied to the system
partition.

If a BCD store already exists on the system partition:
BCDboot will create a new boot entry in the existing BCD store, based
on settings in the BCD-Template file, and remove any duplicate boot
entries that reference the same Windows image.

If there is already a boot entry for the Windows image, and additional
BCD settings are enabled for that boot entry beyond the default values,
these settings can be retained the next time BCDboot is run by using
the /m option to merge the existing boot entry, identified by the OS
Loader GUID into the new boot entry created by BCDboot.