INSTALL WINDOWS XP PROFESSIONAL FROM A MASTER IMAGEIN THIS EXERCISE, Y...

4-11Lesson 1 Explaining the Startup Process

HKEY_LOCAL_MACHINE\SYSTEM\Select subkey of the Registry. The Clone con-

trol set is never modified because it is intended to be an identical copy of the data

used to configure the computer and should not reflect changes made during the

startup process.

Device drivers are loaded and initialized. After creating the Clone control set, the

kernel initializes the low-level device drivers that were loaded during the kernel

load phase. The kernel then scans the HKEY_LOCAL_MACHINE\ SYSTEM\Cur-

rentControlSet\Services subkey of the Registry for device drivers with a value of

0x1 for the Start entry. As in the kernel load phase, a device driver’s value for the

Group entry specifies the order in which it loads. Device drivers initialize as soon

as they load. If an error occurs while loading and initializing a device driver, the

boot process proceeds based on the value specified in the ErrorControl entry for

the driver. Table 4-4 describes the possible ErrorControl values and the resulting

boot sequence actions.

Table 4-4

ErrorControl Values and Resulting Action

ErrorControl

Value Action

0x0 (Ignore) The boot sequence ignores the error and proceeds without displaying an

error message.

0x1 (Normal) The boot sequence displays an error message, but ignores the error and pro-

ceeds.

0x2 (Severe) The boot sequence fails and then restarts using the Last Known Good control

set. If the boot sequence is currently using the Last Known Good control set,

the boot sequence ignores the error and proceeds.

0x3 (Critical) The boot sequence fails and then restarts using the Last Known Good control

set. However, if the Last Known Good control set is causing the critical error,

the boot sequence stops and displays an error message.

Note ErrorControl values appear in the Registry under the subkey HKEY_LOCAL_MACHINE\

SYSTEM\CurrentControlSet\Services\name_of_service_or_driver\ErrorControl.

Services are started. After the kernel loads and initializes device drivers, Session

Manager (SMSS.EXE) starts the higher-order subsystems and services for Windows

XP Professional. Session Manager executes the instructions in the BootExecute

data item, and in the Memory Management, DOS Devices, and SubSystems keys.

Table 4-5 describes the function of each instruction set and the resulting Session

Manager action.

Table 4-5

Session Manager Reads and Executes These Instruction Sets

Data Item or Key Action

Session Manager executes the commands specified in this data item before

BootExecute

it loads any services.

data item

Session Manager creates the paging file information required by the Virtual

Memory Manage-

Memory Manager.

ment key

DOS Devices key Session Manager creates symbolic links that direct certain classes of com-

mands to the correct component in the file system.

SubSystems key Session Manager starts the Win32 subsystem, which controls all input/out-

put (I/O) and access to the video screen, and starts the WinLogon process.

What Happens During the Logon Phase

The logon phase begins at the conclusion of the kernel initialization phase. The Win32

subsystem automatically starts WINLOGON.EXE, which in turn starts the Local Security

Authority (LSASS.EXE) and displays the Logon dialog box. You can log on at this time,

even though Windows XP Professional might still be initializing network device drivers.

Next, the Service Control Manager executes and makes a final scan of the HKEY_

LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services subkey, looking for services

with a value of 0x2 for the Start entry. These services, including the Workstation service

and the Server service, are marked to load automatically.

The services that load during this phase do so based on their values for the DependOn-

Group or DependOnService entries in the HKEY_LOCAL_MACHINE\ SYSTEM\Cur-

rentControlSet\Services Registry subkey.

A Windows XP Professional startup is not considered good until a user successfully

logs on to the system. After a successful logon, the system copies the Clone control set

to the Last Known Good control set.

Note For more information on Last Known Good configuration, see Lesson 3 later in this

chapter.

Lesson Review

Use the following questions to help determine whether you have learned enough to

move on to the next lesson. If you are unable to answer a question, review the lesson

materials and try the question again. You can find answers to the questions in the

“Questions and Answers” section at the end of this chapter.