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Automatically Starting Services

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During system boot, the SCM starts all auto-start services and the services on which they depend. For example, if an auto-start service depends on a demand-start service, the demand-start service is also started automatically.

The load order is determined by the following:

  1. The order of groups in the load ordering group list. This information is stored in the List value in the following registry key:

    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\ServiceGroupOrder

    To specify the load ordering group for a service, use the lpLoadOrderGroup parameter of the CreateService or ChangeServiceConfig function.

  2. The order of services within a group specified in the tags order vector. This information is stored in the following registry key:

    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\GroupOrderList

  3. The dependencies listed for each service.

When the boot is complete, the system executes the boot verification program specified by the ImagePath value of the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\BootVerificationProgram.

By default, this value is not set. The system simply reports that the boot was successful after the first user has logged on. You can supply a boot verification program that checks the system for problems and reports the boot status to the SCM using the NotifyBootConfigStatus function.

After a successful boot, the system saves a clone of the database in the last-known-good (LKG) configuration. The system can restore this copy of the database if changes made to the active database cause the system reboot to fail. The following is the registry key for this database:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSetXXX\Services

where XXX is the value saved in the following registry value: HKEY_LOCAL_MACHINE\System\Select\LastKnownGood.

If an auto-start service with a SERVICE_ERROR_CRITICAL error control level fails to start, the SCM reboots the computer using the LKG configuration. If the LKG configuration is already being used, the boot fails.

An auto-start service can be configured as a delayed auto-start service by calling the ChangeServiceConfig2 function with SERVICE_CONFIG_DELAYED_AUTO_START_INFO. This change takes effect after the next system boot. For more information, see SERVICE_DELAYED_AUTO_START_INFO.