Introduction to the reading sequence of Windows XP startup system files

Windows XP Professional computer Startup Process Overview

--------------------------------------------------------------------------------

Overview

This article describes how to start Microsoft Windows XP on an x86 architecture computer. It aims to give readers a better understanding of the basics of Windows XP Professional Edition. After learning this knowledge, you can find a solution faster when a problem occurs during startup to avoid potential losses. However, it should be noted that this article does not involve troubleshooting and any explanation of the fault. This article only introduces the boot/Startup Process of Windows XP.

--------------------------------------------------------------------------------

Directory
1. Windows XP startup stage Overview
2. Detailed introduction of each startup phase

--------------------------------------------------------------------------------

Windows XP startup stage Overview

From pressing the computer switch to start the computer, to logging on to the desktop to complete the startup, it has gone through the following phases:

1. Pre-Boot phase;

2. Pilot phase;

3. kernel loading phase;

4. initialize the kernel;

5. log on.

--------------------------------------------------------------------------------

Detailed introduction of each startup phase

A) pre-guided phase
This is called the Pre-Boot phase during which the computer is started by pressing the power of the computer and before the Windows XP Professional operating system is started, the computer first runs Power On Self Test (POST) to check the total memory of the system and the status of other hardware devices. If the BIOS of the computer system (Basic Input/Output System) is out-of-the-box, the computer hardware device will be inspected and configured. The computer's Basic Input/Output System (BIOS) locates the computer's Boot device, and the MBR (Master Boot Record) is loaded and run. In the pre-boot phase, the computer will load the NTLDR file of Windows XP.

B) Guiding phase
The Windows XP Professional boot phase contains four small phases.

First, the computer needs to go through the Initial Boot Loader phase (Initial Boot Loader). In this phase, NTLDR converts the computer microprocessor from the real mode to the 32-bit flat memory mode. In real mode, the system reserves KB of memory for the MS-DOS, and the rest of the memory is considered as extended memory, while in 32-bit flat memory mode, the system (Windows XP Professional) regards all memory as available memory. Then, NTLDR starts the built-in mini-file system drivers. Through this step, NTLDR can identify every partition formatted with the NTFS or FAT file system to detect and load Windows XP Professional, here, the initial Boot Loader stage is over.

Then the system comes to the operating system selection stage. If more than one operating system (that is, multiple systems) is installed on the computer, and the boot is correctly set. when ini enables the system to provide the OS selection, the computer display displays an OS menu, Which is NTLDR reads boot. ini result. (For the Operating System menu, there is no way because of the lack of temporary conditions, but I have simulated one, see .)

Boot. ini contains the following content:

[Boot loader]
Timeout = 30
Default = multi (0) disk (0) rdisk (0) partition (1) \ WINDOWS
[Operating systems]
Multi (0) disk (0) rdisk (0) partition (1) \ WINDOWS = "Microsoft Windows XP Professional"/fastdetect
Multi (0) disk (0) rdisk (0) partition (2) \ WINNT = "Windows 2000 Professional"

Here, multi (0) indicates the disk controller, disk (0) rdisk (0) indicates the disk, and partition (x) indicates the partition. NTLDR is used to find the location of the system files of Windows XP Professional. (* This article will not explain in detail the structure of boot. ini, because it has little to do with this topic. If you want to know, you can go to some special websites to query relevant information .) If. if there is only one operating system option in ini or the value of timeout is set to 0, the system does not display the operating system selection menu and directs directly to the unique or default system. After you select to start Windows XP Professional, the operating system selection phase ends and the hardware detection phase begins.

In the hardware detection phase, ntdetect.com collects the computer hardware information list and returns the list to NTLDR, so that the hardware information can be added to the hardware in the Registry HKEY_LOCAL_MACHINE.

After the hardware detection is complete, enter the configuration selection stage. If the computer contains a list of multiple hardware configuration files, you can click the up or down button to select. If there is only one hardware configuration file, the computer will load Windows XP Professional Edition directly with the default configuration file without displaying this screen.

The boot phase ends. During the boot phase, the system will use a total of Files: ntldr, boot.ini, ntdetect.com, ntoskrnl.exe, Ntbootdd. sys, bootsect. dos (optional ).

C) kernel loading stage

During kernel loading, ntldr loads ntoskrnl.exe, which is called the Windows XP kernel. The system loads the Windows XP kernel but does not initialize it. Then, ntldr loads the hardware abstraction layer (HAL, hal. dll), and the system continues to load the HKEY_LOCAL_MACHINE \ system key. NTLDR reads the select key to determine which Control Set will be loaded. The control set contains the driver of the device and the services to be loaded. NTLDR loads the driver of the underlying device whose start key value is 0 under HKEY_LOCAL_MACHINE \ system \ service. When the Current Control Set of the image used as the Control Set is loaded, ntldr passes the Control to the kernel and the kernel initialization starts.

D) initialize the kernel.

At the beginning of the kernel initialization stage, the color Windows XP logo and progress bar are displayed in the center of the screen. At this stage, the system has completed the following four tasks:

The kernel uses the data collected during HARDWARE detection to create the HKEY_LOCAL_MACHINE \ HARDWARE key.

The kernel creates a Clone Control Set by referencing the default value of HKEY_LOCAL_MACHINE \ system \ Current. The Clone Control Set configuration is a backup of computer data, and does not include changes during startup.

The system initializes and loads device drivers. The kernel initializes the underlying drivers that are loaded during kernel loading, and then the kernel scans HKEY_LOCAL_MACHINE \ system \ CurrentControlSet \ service \... the device driver with the start key value of 1. These device drivers are initialized when loaded. If an error occurs, the kernel uses the ErrorControl key value to determine how to handle the error. If the value is 3, the error mark is crisis/critical, the system restarts with LastKnownGood Control Set when an error occurs for the first time. If an error still occurs when you start with LastKnownGood Control Set, the system reports that the startup failed, the error message is displayed, and the system stops the startup; if the value is 2, the error is serious. The system fails to start and restarts with LastKnownGood Control Set. If the system is already started with the value of LastKnownGood, the system ignores the error and continues to start; when the value is 1, the error is normal. The system will generate an error message, but it will still ignore this error and continue to start; when the value is 0, it will be ignored, the system does not display any error information and continues running.

Session Manager starts Windows XP advanced subsystems and services. Session Manager starts Win32 subsystems and Winlogon processes that control all input and output devices and access the display screen. kernel Initialization is complete.

E) Login

Winlogon.exe starts the Local Security Authority, and the Windows XP Professional welcome screen or Login Dialog Box is displayed. At this time, the system may continue to initialize the unfinished driver in the background.

Prompt to enter a valid user name or password.

The Service Controller finally executes and scans HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ Servives to check whether there are services that need to be loaded. The Service Controller searches for services whose start key value is 2 or higher, the service is loaded according to the value of start and the value of DependOnGroup and DepandOnService.

The startup of Windows XP is considered complete only after the user successfully logs on to the computer. After Successful Logon, the system copies the Clone Control Set to the LastKnownGood Control Set. After this step is completed, the system is successful.