Tuesday, August 28, 2012

Windows Vista, Windows 7 startup process

The startup process of Windows Vista, Windows Server 2008, Windows 7 and Windows Server 2008 R2 is different from previous versions of Windows. For Windows Vista, the boot sector loads the Windows Boot Manager (hidden system file BOOTMGR in the C: root directory), which first looks for an active partition, then accesses the Boot Configuration Data store and uses the information to load the operating system.

Boot Configuration Data

Boot Configuration Data (BCD) is a firmware-independent database for boot-time configuration data. It replaces the boot.ini that was used by NTLDR, and is used by Microsoft's new Windows Boot Manager.
Boot Configuration Data are stored in a data file that has the same format as the Windows Registry.[1] The file is located either on the EFI System Partition (on machines that use Extensible Firmware Interface firmware) or in \Boot\Bcd on the system volume (on machines that use IBM PC compatible firmware).

Boot Configuration Data may be altered using a command-line tool (bcdedit.exe), using Registry Editor (regedit.exe), using Windows Management Instrumentation, or with third party tools like EasyBCD.
Boot Configuration Data contain the menu entries that are presented by the Windows Boot Manager, just as boot.ini contained the menu entries that were presented by NTLDR. These menu entries can include:
  • Options to boot Windows Vista by invoking winload.exe.
  • Options to resume Windows Vista from hibernation by invoking winresume.exe.
  • Options to boot a prior version of the Windows NT family by invoking its NTLDR.
  • Options to load and to execute a volume boot record.
Boot Configuration Data allows for third party integration so anyone can implement tools like diagnostics or recovery options.

winload.exe  

The Windows Boot Manager invokes winload.exe—the operating system boot loader—to load the operating system kernel (ntoskrnl.exe) and (boot-class) device drivers. In that respect, winload.exe is functionally equivalent to the operating system loader function of NTLDR in prior versions of Windows NT.





 

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