Index Introduction The BCD Store The System BCD Store Default Paths\Setup (BIOS) Default Paths\Setup (UEFI) BCDEdit - The Basics Check Entries in a BCD Store Devices Devices - locate Backing up the BCD Store Examples - Part 1 Examples - Part 2 Examples - Part 3 Examples - Part 4 BCDEdit Commands BCDEdit Versions Mounting the BCD Store... Acknowledgements Appendices ========= Glossary BCDEdit (version 6.0.6001) BCDEdit (version 6.1.7601) BCDEdit (version 6.3.9600) Device Partition - Data Objects and Elements Alternatives to bcdedit UEFI, BIOS, GPT and MBR

Default Paths/Setup (UEFI)

This page contains the following sections -

• Default System Setup
• UEFI Boot Process
• Locating the BCD Store

Default System Setup

Windows will automatically partition a hard disk during the installation process if an unpartitioned hard disk is selected as the target drive for the operating system. The partition structure and location of the boot files will depend on the version of Windows that is being installed. To illustrate this, 64-bit versions of Windows Vista (SP1), Windows 7 (SP1) and Windows 8.1 were installed on a virtual machine with one unpartitioned disk. The following screenshots were captured from the respective operating system after the installation was complete -

• Windows Vista (SP1) - three partitions were created, only two of which are visible in disk manager -
  
  All three partitions are listed in diskpart -
  

• Windows 7 (SP1) - three partitions were created, only two of which are visible in disk manager. The Windows Recovery Environment (WinRE) was installed on the same partition as the Operating System files -
  
  All three partitions are listed in diskpart -
  

• Windows 8.1 - four partitions were created, only three of which are visible in disk manager. The Windows Recovery Environment (WinRE) was installed to a dedicated partition -
  
  All four partitions are listed in diskpart -
  

Microsoft specifies the use of a Microsoft System Reserved (MSR) partition on systems configured with UEFI firmware on GPT disks. In all of the examples above it's the MSR partition that is missing from the Disk Manager display. As far as I am aware the UEFI specification does not require a MSR partition, however I'm unsure whether Windows will function fully without one.

The following output was obtained using the command line Diskpart tool to check for more detailed information about each partition on the Windows 8.1 installation -
Microsoft Windows [Version 6.3.9600] (c) 2013 Microsoft Corporation. All rights reserved. C:\Windows\system32>diskpart Microsoft DiskPart version 6.3.9600 Copyright (C) 1999-2013 Microsoft Corporation. On computer: USER DISKPART> sel disk 0 Disk 0 is now the selected disk. DISKPART> list part Partition ### Type Size Offset ------------- ---------------- ------- ------- Partition 1 Recovery 300 MB 1024 KB Partition 2 System 99 MB 301 MB Partition 3 Reserved 128 MB 400 MB Partition 4 Primary 39 GB 528 MB DISKPART> sel part 1 Partition 1 is now the selected partition. DISKPART> detail part Partition 1 Type : de94bba4-06d1-4d40-a16a-bfd50179d6ac Hidden : Yes Required: Yes Attrib : 0X8000000000000001 Offset in Bytes: 1048576 Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- * Volume 2 Recovery NTFS Partition 300 MB Healthy Hidden DISKPART> sel part 2 Partition 2 is now the selected partition. DISKPART> detail part Partition 2 Type : c12a7328-f81f-11d2-ba4b-00a0c93ec93b Hidden : Yes Required: No Attrib : 0X8000000000000000 Offset in Bytes: 315621376 Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- * Volume 3 FAT32 Partition 99 MB Healthy System DISKPART> sel part 3 Partition 3 is now the selected partition. DISKPART> detail part Partition 3 Type : e3c9e316-0b5c-4db8-817d-f92df00215ae Hidden : Yes Required: No Attrib : 0X8000000000000000 Offset in Bytes: 419430400 There is no volume associated with this partition. DISKPART> sel part 4 Partition 4 is now the selected partition. DISKPART> detail part Partition 4 Type : ebd0a0a2-b9e5-4433-87c0-68b6b72699c7 Hidden : No Required: No Attrib : 0000000000000000 Offset in Bytes: 553648128 Volume ### Ltr Label Fs Type Size Status Info ---------- --- ----------- ----- ---------- ------- --------- -------- * Volume 1 C NTFS Partition 39 GB Healthy Boot

UEFI Boot Process

The UEFI system boot menu is stored in NVRAM (Non-volatile Random Access Memory) - this is not the Windows boot menu, although a boot menu option for Windows will be added to it during the installation process. A UEFI system boot menu will typically contain entries for all disks/drives attached to the system.

For a GPT type hard disk to boot in UEFI mode it must contain an EFI System Partition - or ESP. The UEFI specification states that the ESP must be formatted with the FAT file system - either FAT12, FAT16 or FAT32.

GPT disks use Globally Unique Identifiers (GUID) for partitions - a ESP type partition will use the C12A7328-F81F-11D2-BA4B-00A0C93EC93B identifier.

Unlike BIOS firmware, UEFI firmware includes file system support - the UEFI specification designates support for FAT32 on fixed disks and FAT12/FAT16 on removable media. Support for additional file systems can be added by vendors. During the boot process the firmware will scan the selected disk for an EFI System Partition and will attempt to load the UEFI Boot Manager -

• On 32-bit UEFI systems the firmware will load \EFI\boot\bootia32.efi
• On (amd64) 64-bit UEFI systems the firmware will load\EFI\boot\bootx64.efi

During the Windows installation process a boot menu option will be added to the UEFI system boot menu - the boot menu stored in NVRAM. On the test system this menu option (titled Windows Boot Manager) pointed to the \EFI\Microsoft\boot\bootmgfw.efi file on the EFI System Partition.

On Windows systems \EFI\boot\bootx64.efi (or \EFI\boot\bootia32.efi) is a copy of the Windows Boot Manager (bootmgfw.efi). During the installation of Windows 7 or 8, two identical copies of the Windows Boot Manager will be added to the EFI System Partition -

• \EFI\boot\boot*.efi (either bootia32.efi or bootx64.efi)
• \EFI\Microsoft\boot\bootmgfw.efi

The Windows Boot Loader will scan the BCD file for boot menu options and settings.

Note on Windows Vista - Windows Vista will not create a copy of bootmgfw.efi as \EFI\boot\boot*.efi. Attempting to boot the disk containing the Windows Vista installation directly from the UEFI System menu will therefore fail as the UEFI Specification is not adhered to (\EFI\boot\boot*.efi is missing). On Windows Vista systems the Windows Boot Manager option in the UEFI System Menu must be used.

Locating the BCD Store

The BCD store can be found at the following path in the EFI System Partition -

• \EFI\Microsoft\boot\BCD

The ESP will probably need to be mounted in order to access it - Windows will not automatically allocate a mount point. The ESP can be mounted using the command-line diskpart tool. Example commands for mounting the second partition on disk 0 (the default setup when Windows 8.1 was installed in a VM - see above) -

• Select Disk 0
• Select Partition 2
• Assign