The Windows Vista Boot Sequences
Both for the exam and for practical application, you should know how to recognize common problems with the OS and be able to make certain it is booting correctly. The sections that follow look at a number of topics related to keeping your OS booting and running properly.
Key Boot Files
Windows Vista requires only a few files, each of which performs specific tasks. These files differ from the files for Windows XP and all previous Windows operating systems. These are discussed next in the order in which they load:
BOOTMGR The Windows Boot Manager (BOOTMGR) bootstraps the system. In other words, this file starts the loading of an OS on the computer. This file replaces NTLDR (used in previous operating systems) and is responsible for switching from real to protected mode during the boot process. The latter mode provides memory protection, multitasking, and other features you expect from the operating system.
BCD The Boot Configuration Data (BCD) file holds information about OSs installed on the computer, such as the location of the OS files.
WINLOAD.EXE The program used to boot Windows Vista. It loads the operating system kernel (NTOSKRNL.EXE).
WINRESUME.EXE If the system is not starting fresh, but resuming a previous session, then WINRESUME.EXE is called by the BOOTMGR.
NTOSKRNL.EXE The Windows OS kernel. The solution to a corrupted NTOSKRNL.EXE file is to boot from a startup disk and replace the file from the setup disks or CD.
System files In addition to the previously listed files, Windows needs a number of files from its system directories (e.g., system and system32), such as the hardware abstraction layer (HAL.DLL), session manager (SMSS.EXE), user session (WINLOGON.EXE) and security subsystem (LSASS.EXE).
We’ll now look at the Windows Vista boot process from start to finish:
1. The system self-checks and enumerates hardware resources. BIOS looks for the Master Boot Record.
2. The Master Boot Record (MBR) loads and finds the volume boot sector. The MBR finds the bootable partition and searches it for the NT boot sector of that partition.
3. The MBR determines the file system and loads BOOTMGR. Information in the boot sector allows the system to locate the system partition and to find and load into memory the file located there.
4. BOOTMGR checks to see if WINRESUME.EXE is needed.
5. BOOTMGR processes BCD.
6. BOOTMGR loads and runs WINLOAD.EXE.
7. WINLOAD.EXE loads NTOSKRNL.EXE and HAL.DLL.NTOSKRNL.EXE holds the OS kernel and also what’s known as the executive subsystems. Executive subsystems are software components that parse the Registry for configuration information and start needed services and drivers. HAL.DLL enables communication between the OS and the installed hardware.
8. The HKEY_LOCAL_MACHINESYSTEM Registry hive and device drivers are loaded and control is transferred to NTOSKRNL.EXE to complete the boot process. It calls the WIN32K.SYS subsystem and the session manager SMSS.EXE.
9. WINLOGON.EXE loads. At this point, you are presented with the Logon screen. After you enter a username and password, you’re taken to the Windows Desktop.
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