Device Manager Registry Keys (Compact 2013)
3/26/2014
Device Manager uses the Active and BuiltIn subkeys of the HKEY_LOCAL_MACHINE\Drivers registry key. Device drivers should never modify the values placed in this part of the registry by Device Manager.
The HKEY_LOCAL_MACHINE\Drivers\Active registry key contains subkeys that track currently active drivers that Device Manager loaded. Device driver setup routines should not modify the Active key's contents, nor should they rely on the presence of any specific values within the Active key other than those listed in the table below. When a driver is loaded, Device Manager passes the path to the driver's Active key with the dwContext parameter to the initialization function. The initialization function can read and create new values in the Active key; however, it is not permitted to access the key after the initialization function returns. The following table shows the subkeys available in the Active registry key.
Subkey |
Description |
|---|---|
BusDriver |
Driver's bus name. The bus driver adds this subkey for its subordinate device. |
BusName |
Device's bus name. The bus driver adds this subkey for its subordinate device. |
DevID |
Unique device identifier added by Device Manager. Unlike the handle value already in the registry, this value is not reused frequently. |
FullName |
Name added by Device Manager and used in conjunction with the \$device namespace. For COM7:, this value is "COM7". For \$device\COM23, this value is "COM23" and there is no "Name" value. |
Name |
Device driver's device file name, for example COM1: or SCR7:. Some devices are unnamed and might not contain this value. This subkey is only present for drivers that specify a prefix. |
Order |
Bus enumerator examines keys according to the Order value. Order can be any DWORD value. Order values do not have to be sequential, and there can be gaps between Order values. If multiple devices have the same Order, there is no guarantee of the load sequence of devices with the same Order value. |
Key |
Registry path to the device. |
Remarks
The Device Manager always starts in boot phase one. Previously, the DWORD boot registry value HKEY_LOCAL_MACHINE \Init\BootVars\Flags specified the boot phase in which the Device Manager was started.
Drivers specified in the boot registry under the HKEY_LOCAL_MACHINE\Drivers\BuiltIn registry key will now be started in boot phase 1. If a driver is not in the boot registry then it will be started in boot phase 2. User-mode drivers cannot be started in boot phase 1 even if they are in the boot registry.
A driver is registered in the boot registry if the registry entry in a .reg file is surrounded by the following lines:
; HIVE BOOT SECTION
; END HIVE BOOT SECTION