About BCD

About BCD

When you start your computer, the first code that executes is the BIOS.

The BIOS reads the master boot record (MBR) from the boot device and transfers control to the boot code stored in the MBR.

 (The Windows setup program writes the MBR to the first sector on the hard disk during installation.)

The boot manager reads the boot entries from the Boot Configuration Data (BCD) store

so they are available to the loader and displays a boot menu to the user.

The boot environment provides a native application programming interface for primitive graphics and other system support.

Boot applications are pieces of code that are located on a boot device and run in the boot environment.

 

Each BCD element represents a specific boot option.

All elements share a common header that describes the element type and data format.

The remainder of the element is determined by the element's data format.

An application can define its own elements or use one of the predefined element types.

 

The BcdElement class is the base for all elements.

A BCD object is a collection of elements that describes the settings for the object that are used during the boot process. There are three main types of objects: application, device, and inherited.

The following are examples of application objects:

• The Windows Boot Manager
• The Windows OS Loader
• The Windows Memory Tester

A device object describes the device-specific properties that are not stored in an application object. Inheritable objects contain elements that contain settings that can apply to more than one object. An object can add the GUID for an inheritable object to its inherited object list. The BcdObject class represents an object.

A BCD store contains objects. Each object is identified by a GUID. The BcdStore class represents a store. The system store is the store that will be read at the next system boot.

See Also

Mapping Boot Options to Elements

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Build date: 1/10/2008

 

 

 

Mapping Boot Options to Elements

The following table provides a mapping from the boot options in Boot.ini to the BCD elements.

Option	Element type
/3GB	BcdOSLoaderInteger_IncreaseUserVa
/BASEVIDEO	BcdOSLoaderBoolean_UseVgaDriver
/BAUDRATE=	BcdLibraryInteger_SerialDebuggerBaudRate
/BOOTLOG	BcdOSLoaderBoolean_BootLogInitialization
/BOOTLOGO
/BREAK	BcdOSLoaderBoolean_DebuggerHalBreakpoint
/BURNMEMORY=	BcdOSLoaderInteger_RemoveMemory
/CHANNEL=	BcdLibraryInteger_1394DebuggerChannel
/CLKLVL
/CMDCONS
/CRASHDEBUG
/DEBUG, BOOTDEBUG	BcdLibraryBoolean_DebuggerEnabled
/DEBUG	BcdOSLoaderBoolean_KernelDebuggerEnabled
/DEBUGPORT=	BcdLibraryInteger_DebuggerType
/DEBUGPORT=	BcdLibraryInteger_SerialDebuggerPort
/EXECUTE	BcdOSLoaderInteger_NxPolicy
/FASTDETECT
/HAL=	BcdOSLoaderString_HalPath
/INTAFFINITY
/KERNEL=	BcdOSLoaderString_KernelPath
/LASTKNOWNGOOD	BcdOSLoaderBoolean_UseLastGoodSettings
/MAXMEM=	BcdLibraryInteger_TruncatePhysicalMemory
/MAXPROCSPERCLUSTER=	BcdOSLoaderInteger_ClusterModeAddressing
/MININIT	BcdOSLoaderBoolean_WinPEMode
/NODEBUG
/NOEXECUTE	BcdOSLoaderInteger_NxPolicy
/NOGUIBOOT	BcdOSLoaderBoolean_DisableBootDisplay
/NOLOWMEM	BcdOSLoaderBoolean_NoLowMemory
/NOPAE	BcdOSLoaderInteger_PAEPolicy
/NOSERIALMICE=
/NUMPROC=	BcdOSLoaderInteger_NumberOfProcessors
/onECPU	BcdOSLoaderBoolean_UseBootProcessorOnly
/PAE	BcdOSLoaderInteger_PAEPolicy
/PCILOCK	BcdOSLoaderInteger_UseFirmwarePciSettings
/RDRPATH=
/REDIRECT	BcdOSLoaderBoolean_EmsEnabled
/SAFEBOOT:	BcdOSLoaderInteger_SafeBoot
/SCIORDINAL:
/SDIBOOT=
/SOS
/TIMERES=
/USE8254
/USERVA=	BcdOSLoaderInteger_IncreaseUserVa
/WIN95
/WIN95DOS
/YEAR=

See Also

BcdLibraryElementTypes
BcdOSLoaderElementTypes

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Build date: 1/10/2008