BCD provides a firmware-independent mechanism for manipulating boot environment data for any type of Windows system. Windows Vista and later versions of Windows will use it to load the operating system or to run boot applications such as memory diagnostics. Some key characteristics include:
BCD abstracts the underlying firmware. BCD currently supports both PC/AT BIOS and EFI systems. BCD interfaces perform all necessary interaction with firmware. For example, on EFI systems, BCD creates and maintains EFI NVRAM entries.
BCD provides clean and intuitive structured storage for boot settings.
BCD interfaces abstract the underlying data store.
BCD is available at run time and during the boot process.
BCD manipulation requires elevated permissions.
BCD is designed to handle systems with multiple versions and configurations of Windows, including versions earlier than Windows Vista. It can also handle non-Windows operating systems.
BCD is the only boot data store that is required for Windows Vista and later versions of Windows. BCD can describe NTLDR and the boot process for loading of earlier versions of Windows, but these operating systems are ultimately loaded by Ntldr and must still store their boot options in a boot.ini file.
Note: If a system includes earlier versions of Windows along with Windows Vista, the earlier versions should be installed first.
There are two approaches to modifying the settings that are contained in BCD:
Users can interact with BCD through several tools. The details of what can be modified depend on the particular tool.
Developers can programmatically manipulate a BCD store through the BCD WMI provider. The WMI provider supports a unified programming interface that can be used for both local and remote management of BCD stores. The interface is independent of the underlying firmware, so developers can write one application that works on any type of system.
Note: BCD’s data store is a registry hive, but that hive should not be accessed with the registry API. Interaction with the underlying firmware occurs in the supported BCD interfaces. For this reason, BCD stores should be accessed only through the associated tools or WMI API.
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