Jjhou during Windows XP startup

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• X86 system-based startup process

 

This article is translated from Understanding the Startup Process in Windows XP Resource Kit Web Resource. To diagnose and fix Startup faults, you need to understand what happened during Startup. The first step is to isolate the startup problem and determine whether the problem occurs before or after Microsoft Windows XP Professional is started. The root cause of startup failure, including related factors, may come from many aspects, such as user errors, application errors, hardware problems, and virus problems. If the problem is too serious, you may need to reinstall Windows XP Professional or restore the file from the backup media. InXOn the 86 system, operating system loader (Ntldr) may mean that the startup file is lost or deleted, the Hard Disk Master Boot Record (MBR) is damaged, or the partition table is located, or the Boot Sector is damaged. If the problem occurs during startup, the system may have incompatible software or drivers, incompatible or incorrectly set hardware, or damaged system files. Enable orX86 the system is similar. For details, see "Startup Phases for Itanium-based Systems"

X86 system-based startup process

Windows XP Professional startup is similar to Microsoft Windows NT version 4.0 and Microsoft Windows 2000, unlike Microsoft MS-DOS, Microsoft Windows 95, Microsoft Windows 98, and Microsoft Windows Millennium Edition (Windows Me) these systems. All systems running Windows XP Professional follow the following startup sequence:

• Power-on self-check (POST) Stage
• Initialize the startup phase
• Start the loading phase
• Hardware Detection and setup phase
• System Core Loading phase
• Login phase

The above startup process is applicable to system startup or restart after normal shutdown, except when the system is restored from sleep or standby, for the latter, see the subsequent chapter "Resolving Power Management Problems on x86-based Systems". For Windows XP Professional to boot, system and boot partitions must contain Table 28. 1..Table 28.1 Windows XP Professional startup files on x86 systems

File Name
File Location
Description

Ntldr
System partition root directory
Operating system loader

Boot. ini
System partition root directory
This file specifies the installation path for Windows XP Professional. For a multi-Boot system, Boot. ini contains an operating system selection menu displayed on the Boot menu.

Bootsect. dos (applicable only to multi-boot systems)
System partition root directory
Ntldr will mount this file to read Windows XP Professional multi-boot system settings that may contain MS-DOS, Windows 95, Windows 98, or Windows Me OS. Bootsect. dos contains the Boot Sector of these operating systems. The file attributes are system and hidden.

Ntdetect.com
System partition root directory
This file will scan hardware settings and pass them to Ntldr

Ntbootdd. sys
System partition root directory (this file is required by devices such as SCSI or ATA that the firmware itself is disabled or do not support INT-13 interrupt extension calls ).
This driver is used to access The hard drive that is connected to SCSI or ATA without using BIOS. the contents of this file depend on The startup controller used.

Ntoskrnl.exe
SystemrootSystem32
The core of the Windows XP Professional operating system (also called kernel ). As part of the kernel, code running in the processor privileged mode allows direct access to system data and hardware.

During Windows XP Professional operating system installation, if it is a single-processor system, the setup program copies the Ntoskrnl.exe file from the operating system disc. If it is a multi-processor system, setup copies Ntoskrnlmp.exe from the installation disc and renames "ntoskrnl.exe.

Hal. dll
SystemrootSystem32
Hardware Abstraction Layer dynamic (HAL) link library files. HAL abstracts extracts underlying hardware information from the operating system and provides public programming interfaces for devices of the same type.

The Microsoft Windows XP Professional operating system CD contains several Hal files. Setup copies the files suitable for your system hardware settings to your computer and renames them Hal. dll.

System registry file
SystemrootSystem32ConfigSystem
This registry file contains the data required to create the HKEY_LOCAL_MACHINESYSTEM registry key value. This key value contains the information required for the operating system to start devices and system services.

Device drivers
SystemrootSystem32Drivers
Driver files of some hardware devices, such as the keyboard, mouse, and video card.

Note:

• Windows NT 4.0, Windows 2000, and Windows XP Professional defines that the "System" and "start" partitions are different from operating systems. The system volume contains the files required to start Windows XP Professional, such as Windows loader (Ntldr ). Start Windows XP Professional operating system files and folders suchSystemrootAndSystemrootSystem32. On an x86 system-based computer, the boot volume and system volume can be but not necessarily the same volume.

In table 28.1, systemroot is one of the many environment variables used to associate strings such as files and file paths to variables for use by Windows XP Professional applications and services. For example, by using environment variables, different scripts can run on computers with different environment settings. You can runSetCommand to view the list of environment variables. For more information about environment variables, see "To add or change the values of environment variables" in Windows XP Professional. For more information about System Files, see "System Files Reference"
Power-on self-check

When you turn on the computer, the central processor unit (CPU) begins to execute commands stored in the Basic Input/Output System (BIOS. BIOS, a firmware that contains some code. The processor starts the computer based on the Code and communicates with standard peripheral devices to form a minimal environment, so that other complex code can be loaded, it has nothing to do with the operating system installed on the computer. The first step in the computer startup process is power-on self-check (POST). POST is responsible for completing the following system and detection functions:

• Perform hardware initialization detection, such as testing the current total memory
• Verify the device required to start the operating system, such as the hard disk
• Retrieving System settings from CMOS located on the motherboard means that when you are down, some information will be maintained in the CMOS memory, for example, the hardware settings stored in CMOS memory contain startup settings and plug-and-play information.

After the motherboard power-on self-check (POST) is completed, additional boards with their own firmware (such as graphics cards and hard disk controllers) start to perform self-detection. To set firmware parameters for these systems and peripheral devices, see the system documentation provided by the relevant vendor.
Initialize the startup phase

The settings stored in CMOS memory after the POST phase, such as startup settings, indicate the devices that can boot the operating system. For example, if you specify A floppy disk as the preferred device for startup and use the hard disk as the secondary device (some firmware files are displayed as "A, C "), the following situations may occur during startup:
A floppy disk is inserted in the drive.

The BIOS sets the search as a floppy disk to start. If a floppy disk exists, it loads the 0-sided, 0-sector, and 1-sector (the Boot Sector of the floppy disk) to the memory. If a floppy disk cannot be started, the following error will be prompted:Non-system disk or disk errorReplace and press any key when readyThe computer will always display the above information until you insert a boot floppy disk or drive out a floppy disk to restart the computer.
No floppy disk in the floppy disk

If you do not insert a floppy disk after restarting the computer, the computer will load instructions in the region where the Master Boot Record (MBR) is located. The MBR is located in the first sector of the boot hard disk. It contains commands (called the Boot Code) and a table (called a partition table) that identifies the primary and extended partitions ). The BIOS loads the MBR to the memory and hands over control to the Code in the MBR. The computer then searches for the partition table and finds the active partition. The first sector of the active partition contains the startup code, which allows the computer to perform the following operations:

• Determine the file system used
• Locate and start the operating system to load files, Ntldr.

If the active partition does not exist or the startup sector information is lost or incorrect, the following message is displayed:Invalid partition tableError loading operating systemMissing operating systemBOOT: Couldnt find NTLDRNTLDR is missingIf the active partition is located successfully, the code in the Start partition will find and start Ntldr, and then the BIOS completes the Mission to release control about the disk and file system, MBR, for more details about partitions and startup slice, see "File Systems" and "Troubleshooting Disks and File Systems"
Specify the startup sequence of other startup devices

In addition, some computer firmware allows you to boot the operating system from other devices, such:

• CD-ROMs
• Nic
• Removable storage media, such as LS-120 drives or Iomega Zip drives
• Some memory connected to a portable computer

In most computers, you can specify the startup sequence, such as "CDROM, A, C ". when you specify the startup sequence such as "CDROM, A, C", the startup will be as follows:

1. The computer searches the CD-ROM as the boot medium. If a CD (CD) can be started, the computer will be used as the boot device, otherwise the computer will find the next boot device according to the set boot sequence.
2. The computer searches for a floppy disk as the boot medium. If a floppy disk can be started, the computer uses a floppy disk as the boot device. Otherwise, an error message is displayed, and the next Startup Device is searched according to the set startup sequence.
3. The computer uses the hard disk as the boot device. When both the CD-ROM drive and the floppy drive are empty, the computer will only use the hard disk as the boot device. However, the code on the boot Media controls the transmission of the hard disk. For example, when you boot the system with a bootable Windows XP Professional operating system CD, the Setup program will check whether there is a available hard disk for Windows XP Professional installation process, if retrieved, the following Press any key to boot from CD is prompted, which gives you an option to skip the CD-ROM startup without pressing any key.

You cannot use a boot CD boot system that cannot be started, and a boot CD that cannot be started may increase the system boot time. If you do not intend to boot the system from the CD, remove the disc from the CD-ROM drive before starting. For more information about the startup sequence options, see your system documentation.
Start the loading phase

To load the Startup file from the boot partition, perform the following steps:
Set the x86 system processor to run in 32-Bit Memory protection mode

Based onX86 computers run in real mode when started. In this mode, the processor disallows some features to be compatible with software running on 8-bit and 16-bit processing. Ntldr then switches the processor to 32-Bit mode, which allows access to large memory capacity and runs Windows XP Professional
Start the File System

Ntldr contains program code required to allow Windows XP Professional to read and write NTFS or file allocation table (FAT16 or FAT32) file systems.
Read the Boot. ini file

Ntldr analyzes the Boot. ini file to determine the location of the Boot partition of the operating system. If you use the single-system boot settings, Ntldr will then start Ntdetect.com to initialize the hardware detection. if a multi-system boot exists, this may include Windows XP Professional, Windows 2000, Windows NT 4.0, Windows 95, Windows 98, Windows Me, or MS-DOS and other possible operating systems, you will see an operating system selection menu at startup. Note:

• If a computer running Windows NT 4.0 needs to access the NTFS Volume attached to Windows 2000 or Windows XP Professional, install at least Service Pack 4. For information about NTFS interoperability, see "File Systems"

If you select Windows XP Professional, Windows 2000, or Windows NT 4.0, Ntldr will then start the hardware detection phase. If not, other systems in the sector will be booted. If you select Windows 95, Windows 98, Windows Me, or MS-DOS, Ntldr will scan the Bootsect. dos file, read the MBR code contained in it, and execute it. For more information about Boot. ini, see "Reviewing and Correcting Boot. ini Settings on x86-based Systems"
Detect hardware and hardware configuration files

In this phase, Ntldr starts Ntdetect.com, which performs a basic hardware scan. Ntldr then scans the Boot. ini information and stores the hardware and software information in the Registry and sends it to Ntoskrnl.exe. Ntdetect.com checks the hardware Configuration information (such as the connection or no connection settings on a portable computer) and saves the information in the Advanced Configuration and Power Interface (ACPI) table. The ACPI compatible firmware allows Windows XP Professional to detect device power management features and device resource requirements. For ACPI please refer to http://www.microsoft.com/windows/reskits/webresources.
Hardware Detection and setup phase

After reading Boot. ini and completing its tasks, Ntldr starts Ntdetect.com. On the x86 system, Ntdetect.com calls the system routine to collect installed hardware information and return the collected information to Ntldr. Ntldr collects the information and stores it in the internal database, start Ntoskrnl.exe and pass the information to it. The hardware device information collected by Ntdetect.com is as follows:

• Firmware information, such as date and time
• Bus and board types
• Graphics card
• Keyboard
• Communication Port
• Hard Disk
• Floppy Disk
• Input Device (such as mouse)
• Parallel Port
• Devices installed on the Industrial Standard Architecture (ISA) Bus

Ntdetect.com plays an important role in device scanning of non-ACPI compatible computers. For these types of computers, firmware, instead of the operating system, determines the resources allocated to the device. For computers that use ACPI firmware, Windows XP Professional allocates resources to hardware devices. At this stage, Ntdetect.com collects hardware information. Windows XP Professional creates a separate default hardware configuration file for the desktop computer and two default configuration files for the portable computer. For a portable computer, the operating system selects an appropriate configuration file based on the hardware status on the current computer.

• Desktop Computer. Profile 1
• Portable computer.
  • Docked Profile
  • Undocked Profile

Hardware configuration files are very useful for portable computers because the hardware status of these computers is usually not static, device drivers without a list in a specific hardware configuration file will not be loaded. For information on creating and using Hardware configuration files, see Windows XP Professional Help and Support Center, or refer to the knowledge base document 225810, "How to Create Hardware Profiles on Windows 2000? Based Mobile Computers, "Find this document, please query the Knowledge Base link on the Web Resources page http://www.microsoft.com/windows/reskits/webresources, and you can also view" Managing Devices "and" Supporting Mobile Users"
Core Loading phase

Ntldr is responsible for loading Windows core layer (Ntoskrnl.exe) and Hardware Abstraction Layer (HAL) to the memory. The Hal. dll file used by your system can change. During installation, the Windows XP Professional installer selects a copy from several HAL files to the system (see table 28.2 for a list of these files) and renames it Hal. dll. View computer description in Device Manager

1. In the run dialog box, enter devmgmt. msc and click OK.
2. In the Device Manager, expand the computer to view the description of your computer. By comparing the description in the Device Manager and the description in table 28.2 below, you can determine to copy the HAL file from the Windows XP Professional operating system CD to your system

Table 28.2 description of different Hal. dll files

Computer description in Device Manager
HAL file copied

ACPI multi-processor PC
Halmacpi. dll

ACPI single processor PC
Halaacpi. dll

Advanced Configuration and Power Interface (ACPI) PC
Halacpi. dll

MPS multi-processor PC
Halmps. dll

MPS single processor PC
Halapic. dll

Standard PC
Hal. dll

Compaq SystemPro multi-processor or fully compatible
Halsp. dll

The kernel layer and the Hardware Abstraction Layer HAL initialize a group of software components, collectively known as windows execution bodies. Windows executes the information stored in the registry control sets and starts services and drivers. For more information about Windows executive services, see "Common Stop Messages for Troubleshooting"

Control Sets

Ntldr reads related information from the HKEY_LOCAL_MACHINESYSTEM registry subkey. The data in this subkey is created in the System32Config System file. Therefore, Ntldr can determine which device drivers are loaded at System startup. Generally, there are several control sets in the registry. The sequence number is determined by how long the system has set .. Tip:

• Do not directly edit the Registry unless necessary. Registry Editor bypasses the system protection mechanism. Your modifications may damage the system. In serious cases, you even need to reinstall Windows. If you have to edit the Registry, back up the Registry in advance and read more about the Registry Reference chapter http://www.microsoft.com/windows/reskits/webresources in Microsoft Windows 2000 Server Resource Kit.

A typical registry control set sub-key is as follows:

• CurrentControlSet, a registered item in SelectCurrent, pointing to ControlSetXxxSub-key pointer (XxxRepresents a control set number, such as 001)
• Clone, a copy of CurrentControlSet, which is created every time you start the computer. (Gnaw0725 note: this is the case in the original article and remains to be verified)
• Select, which includes the following key values:
  • DefaultThe Pointer Points to the control set number (for example, 001 = ControlSet001) used by the system for the next login ). If no error occurs, orLastKnownGoodSet the startup item. The control set number isDefault, Current andLastKnownGoodEffect of registration items (assuming that the current user can log on successfully)
  • Current, Pointing to the control set used to start the system
  • Failed, Pointing to the control set that failed to start Windows XP Professional. When you use the LastKnownGood option to start the system, this item is updated (gnaw0725 Note: indicates the control group of data generated by Windows XP When the startup fails to be saved. This control group does not exist until the user calls the "Last correct configuration" option for the first time .)
  • LastKnownGood, Pointing to the control set used by the last user session. When a user logs on, the LastKnownGood control set is updated by the settings used by the previous user session.

Unless you select Last Known Good Configuration from the Windows Advanced Options menu, Ntldr uses the control set marked by the Default key value. The core layer uses the internal data structure provided by Ntldr to create the HKEY_LOCAL_MACHINEHARDWARE sub-key, which contains hardware information collected during the system startup phase. The data contains information including various hardware components and system resources allocated to each device. You can monitor information about Last Known Good Configuration during core layer loading by viewing the progress indicator displayed during startup, you can refer to "Tools for Troubleshooting" Windows XP Professional supports device extensions. New or updated drivers do not exist on Windows XP Professional operating system disks, but are provided by hardware vendors. The driver is the core mode component and must be Drivers are kernel-mode components required by devices to function within an operating system. The service is a component that supports operating system functions and applications. Compared with a user application, a service can run in a different context and generally does not provide options that users can set. Services, such as Print Spooler printing offline, can be run without user logon, and has nothing to do with the user logging on to the system. Windows XP Professional Drivers and service system files are usually stored in the systemrootSystem32 and systemrootSystem32Drivers directories and saved with extensions such as. exe,. sys, or. dll. The driver is also a service, so during core layer initialization, Ntldr and Ntoskrnl.exe determine the loaded driver and service order according to the values stored in the HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesservicename registry subkey. For example, Ntldr first searches for Services with a Start value of 0 in the Services subkey, such as a hard disk controller. After Ntldr starts ntoskrnl.exe, A ntoskrnl.exe component searches for and starts drivers, such as the network protocol. These startup Item Start values are 1. Table 28.3, And the Start item values are listed in decimal format ). The Start value of a Boot-Type Driver (entry with a Start value of 0) is always 0, because Windows XP Professional requires their support.

Table 28.3 <service name> Start item assignment

Value
Start type
Description of the value assignment of the Start item

0
Boot
Specify the mounted Driver Based on the firmware call mode on the x86 system Ntldr or Itanium IA64ldr. If no error occurs, the Kernel will start the driver.

1
System
Specifies the driver called by Windows XP Professional boot drivers during Kernel initialization.

2
Auto load
Specifies the driver or service that is loaded by the Session Manager (Smss.exe) or service controller (Services.exe) at system startup.

3
Load on demand
Specifies a driver or service that is manually started by a user, process, or other service.

4
Disabled
Specifies a disabled (not started) driver or service.

Table 28.4 lists some values of Type items in decimal format)
Table 28.4 <service name>TypeItem assignment

Value
Type assignment description

1
Specify a core device driver

2
Specify a file system driver (also a core device driver)

4
Specify parameters to pass to the device driver

16
Specify a service that complies with the service control protocol. The service can run in a process independently and can be started by the service controller.

32
Specify a service that can share a process with other services

Some drivers and services need to determine the dependency between them before starting. View HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesServicenameDependOnGroup andDependOnServiceYou can find the list of dependencies. For information about how to use dependency to block or delay the startup of a driver or service, see "Temporarily Disabling Services ". The service sub-key also contains information that affects how drivers and services are loaded. Table 28.5 describes some of these sub-Keys.
Table 28.5 other registry <service name> items

Item
Description

DependOnGroup
At least one project in this group must be loaded before the current service is loaded. Sub-key SYSTEMCurrentControlSetControlServiceGroupOrder contains the order of Service Group Loading

DependOnService
The service described in this list must be loaded before the current service.

Description
Component Description

DisplayName
Display name of the specified component

ErrorControl
To control a driver error, the system must use the LastKnownGood control set or prompt an error stop message.

If the value is 0x0 (ignore, no error report), no warning is displayed. Continue to start.

If the value is 0x1 (normal, report error), record the error to the system log and prompt the warning information, but continue the startup process.

If the value is 0x2 (severe), record the event to the system log, use the LastKnownGood settings, restart the system, and execute the startup process.

If the value is 0x3 (critical), log the event to the system log, use the LastKnownGood settings, and restart the system. If LastKnownGood is already used for the current startup, the error stop message is displayed.

Group
Specifies the group to which the driver or service belongs. This setting allows the driver or service to start synchronously (compared to the file system driver). The List item in HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlServiceGroupOrder specifies the sequence in which group items start.

ImagePath
If an ImagePath item exists, it indicates the path and file name of the driver or service. You can use Windows Explorer to verify these paths and file names.

ObjectName
Specify an object name. If the Type item specifies a Windows XP Professional Service, it indicates the account name used for login during service running.

Tag
Specify the startup sequence of a driver in the driver group.

Session Manager

After the sub-keys of the Registry marked as Boot and Startup data are executed, the kernel starts to load the Session Manager, which (Smss.exe) for subsequent important initialization tasks, such:

• Create System Environment Variables
• Start the Windows subsystem core protection mode (implemented through systemrootSystem32Win32k. sys), which switches Windows XP Professional from text mode to graphics mode. Windows-based applications run on the Windows subsystem. In this environment, applications are allowed to access functional functions of the operating system, such as displaying information on the screen.
• Start the Windows subsystem user mode section (implemented through systemrootSystem32Csrss.exe ).
• Start the login Manager (implemented through systemrootSystem32Winlogon.exe ).
• Create an auxiliary virtual memory page file
• To store the list of objects in the subkeys in the next column, perform the delayed renaming operation. HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSession ManagerPendingFileRenameOperations. For example, after you install a new driver or application, the system may prompt you to restart so that Windows XP Professional can replace the file currently in use.

The Windows subsystem and applications based on it are user-mode processes that cannot directly access hardware and device drivers. Process execution in user mode has a lower priority than the core process. When the operating system requires more memory, it can cache the memory used by the process in user mode to the virtual page file. For information about user mode and core mode components, see "Common Stop Messages for Troubleshooting ". Session Manager searches for the registry to obtain service information. The registry key value is as follows:

• HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSession Manager contains a list of commands run before the service is loaded. The Autochk.exe tool is specified by the value of the BootExecute item and the virtual Memory (page file) settings stored in the Memory Management subkey. Autochk is a version of the Chkdsk tool. If the operating system detects a file system error and needs to be fixed before the startup process is completed, it runs at startup. About Autochk and Chkdsk, "Troubleshooting Disks and File Systems ".
• HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSession ManagerSubsystems contains a list of valid subsystems. For example, Csrss.exe contains a part of the Windows subsystem in the user mode.
• HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesservicename. Service Control Manager initializes services set to enable automatic loading.

Logon phase

In this phase, Windows subsystem starts Winlogon.exe. This module serves the system to complete user login or logout. Winlogon.exe provides the following functions:

Start the service subsystem (Services.exe), also known as the Service Control Manager (SCM ).

Start the Local Security Authority (LSA) (Lsass.exe ).

When the logon prompt is displayed, the CTRL + ALT + DEL key combination is detected. Graphical Identification and verification Graphical Identification and Authentication (GINA) component obtains the user name and password, and sends the information to LSA for security verification. If you provide valid authentication, you can use the Kerberos V 5 authentication protocol or NTLM to obtain or access permissions. Information about security components, such as LSA, Kerberos V5 protocol or NTLM, Distributed Systems Guide of the Microsoft Windows 2000 Server Resource Kit. when Service Control Manager initializes and automatically loads Service items and drivers, Winlogon starts to initialize the security and authentication components. After a user logs on, the system performs the following actions:

• Update Control sets.The control set isLastKnownGoodRegistered items are affected andCloneItem.CloneIs a copy of The CurrentControlSet item, which is created every time you start the computer. When a user logs on, the LastKnownGood control set is updated by the settings used by the previous user session.
• Implementation Strategy. Group Policy settings are implemented on user and computer accounts. For more information about group policies, see "Planning Deployments," "management policies tops," and "Authorization and Access Control ", and the "Group Policy" section in the distributed systems Guide in Windows 2000 Server Resource Kit, you can also refer to the link to the Change and Configuration Management Deployment Guide on its website Resource site http://www.microsoft.com/windows/reskits/webresources.
• Run the Startup Program.Windows XP Professional starts the login script, starts the program group, and starts the service items associated with the following registry subkeys and startup directories:
  • HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRunonce
  • HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionpoliciesExplorerRun
  • HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
  • HKEY_CURRENT_USERSoftwareMicrosoftWindows NTCurrentVersionWindowsRun
  • HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
  • HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunOnce
  • SystemdriveDocuments and SettingsAll UsersStart MenuProgramsStartup
  • SystemdriveDocuments and SettingsusernameStart MenuProgramsStartup
  • WindirProfilesAll UsersStart MenuProgramsStartup
  • The windirProfilesusernameStart MenuProgramsStartup windirProfiles directory is only available on Windows NT 4.0.

After the user successfully logs on to the computer, the Windows XP Professional startup process is complete.
Plug-and-play Detection

Plug-and-play detection does not work in sync with the login process. It relies on system firmware, hardware, device drivers, and operating system functions to detect and enumerate new devices. Windows XP Professional optimizes plug-and-play support for devices that use ACPI firmware and allows enhancements, such as hardware resource sharing.

When plug-and-play is well coordinated, Windows XP Professional detects new devices, allocates system resources, installs or requests drivers with minimal user participation. ACPI features are very useful for mobile users. These features can well support features such as standby, sleep, and cold hot swapping.

For plug-and-play detection and system resources, see "Managing Devices" and "Supporting Mobile Users" ------------------------------------- digress: When I translate this article halfway, seeing Mr. Hou Jie's masterpiece on science and technology translation, here is 2001/12/08, Hou Jie at the invitation of the Translation Research Institute of Normal University, made an open speech (http://jjhou.csdn.net/article01-6.htm) rough look, can't stop, master zhennai! Here is his personal website http://jjhou.csdn.net/