Boot Configuration Data (BCD) Objects
Application object is the most common type of BCD object. Application object is the object type for Windows Boot Manager, Windows boot loader objects including NTLDR, Windows resume loader, and Windows memory tester.
The following table gives the GUID for some commonly used application objects.
Description |
Alias |
GUID |
Windows Boot Manager |
{bootmgr} |
9dea862c-5cdd-4e70-acc1-f32b344d4795 |
Firmware Boot Manager |
{fwbootmgr} |
a5a30fa2-3d06-4e9f-b5f4-a01df9d1fcba |
Windows Memory Tester |
{memdiag} |
b2721d73-1db4-4c62-bf78-c548a880142d |
Windows Resume Application |
No alias |
147aa509-0358-4473-b83b-d950dda00615 |
Legacy Windows Loader |
{ntldr} |
466f5a88-0af2-4f76-9038-095b170dc21c |
Current boot entry |
{current} |
fa926493-6f1c-4193-a414-58f0b2456d1e |
Default boot entry |
{default} |
|
BCD application objects can have two characteristics and they are image type and application type. Image type specifies how the executable is loaded. The following table lists the valid image types, along with the associated numerical value.
Description |
Value |
Firmware application |
0x1 |
Boot application |
0x2 |
Ntldr-based loader object |
0x3 |
Real-mode application |
0x4 |
Application type specifies what the application does. The following table lists the standard application types, along with their associated numerical value.
Description |
Value |
Description |
Firmware boot manager |
0x1 |
Applies only to EFI systems. |
Windows boot manager |
0x2 |
Controls boot flow. In a dual-boot system, displays a boot selection menu to the user. |
Windows boot loader |
0x3 |
Loads a particular version or configuration of Windows. |
Windows resume application |
0x4 |
Restores Windows to its running state when a computer resumes from hibernation. |
Windows memory tester |
0x5 |
A memory diagnostics application. |
Ntldr |
0x6 |
Applies only to PC/AT BIOS systems. Loads versions of Windows earlier than Windows Vista. |
Boot sector |
0x8 |
A 16-bit real-mode application. Applies only to PC/AT BIOS systems. Can be used to restart the boot process and load a non-Windows operating system. |
BCD inheritable objects are containers for elements that are shared across multiple BCD object instances. Some of these inheritable objects are listed below.
Alias |
GUID |
Description |
{badmemory} |
5189b25c-5558-4bf2-bca4-289b11bd29e2 |
Global RAM defect list. |
{bootloadersettings} |
6efb52bf-1766-41db-a6b3-0ee5eff72bd7 |
Global settings that should be inherited by all Windows boot loader applications. |
{dbgsettings} |
4636856e-540f-4170-a130-a84776f4c654 |
Global debugger settings that can be inherited by any boot application. |
{emssettings} |
0ce4991b-e6b3-4b16-b23c-5e0d9250e5d9 |
Global Emergency Management Services settings that can be inherited by any boot application. |
{globalsettings} |
7ea2e1ac-2e61-4728-aaa3-896d9d0a9f0e |
Global settings that should be inherited by all boot applications. |
{resumeloadersettings} |
1afa9c49-16ab-4a5c-901b-212802da9460 |
Global settings that should be inherited by all resume applications. |
There are complicated devices that require more than one element to describe. A BCD device object is a container for BCD elements for a complex device.
Source of Information: Microsoft White Paper on Boot Configuration Data
