Microsoft KB Archive/102985

= REG: CurrentControlSet Entries PART 2: SessionManager =

Article ID: 102985

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Advanced Server 3.1
 * Microsoft Windows NT Workstation 3.1
 * Microsoft Windows NT Advanced Server 3.1

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This article was previously published under Q102985



The article contains REGISTRY entries for the CurrentControlSet\Control Subkeys Part 2--Session Manager entries.

For listings of the other control subkeys under CurrentControlSet, see the articles:

CurrentControlSet Part 1, containing:


 * BootVerificationProgram
 * ComputerName
 * DisplayDriver
 * GroupOrderList
 * HiveList
 * KeyboardLayout
 * Lsa
 * NetworkProvider
 * Nls
 * PriorityControl
 * ProductOptions
 * ServiceGroupOrder

and

CurrentControlSet Part 3, containing:


 * Setup
 * TimeZoneInformation
 * VirtualDeviceDrivers
 * Windows
 * WOW

CURRENTCONTROLSET\CONTROL SUBKEYS ENTRIES
This key contains parameters that control system startup, such as subsystems to load, the size and location of paging files, and so on.

NOTE: The system must be restarted for any changes in the Control key to take effect.

SESSION MANAGER CONTROL ENTRIES
The Session Manager subkey contains the global variables used by the Session Manager. These values are stored under the following Registry path:   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager

BootExecute REG_MULTI_SZ
Default:  autocheck autochk * Specifies programs to run during startup. For example, if CONVERT.EXE has been used to convert the file system on a hard disk drive, this value is added to BootExecute so that conversion occurs when the system is restarted: BootExecute = autocheck autoconv \DosDevices\x: /FS:NTFS

CriticalSectionTimeout REG_DWORD
Default:  0x278d00 Specifies the deadlock time-out for critical sections. Usually, retail installations of Windows NT will not time-out and detect deadlocks.

GlobalFlag REG_DWORD
Default:  0x21100000 Controls various Windows NT internal operations. You can change this value to disable the OS/2 subsystem if you want to run bound applications in a VDM, rather than under the OS/2 subsystem. Set this value to 20100000 to disable the OS/2 subsystem.

ObjectDirectories REG_MULTI_SZ
Default:  \DosDevices \Windows \RPC Control Lists the object directories to create during startup. Do not edit these entries.

RegisteredProcessors REG_DWORD
Default:  0x4

ResourceTimeoutCount REG_DWORD
Default:  0x9e340 The number of 4-second ticks that need to transpire before a resource time- out occurs. Retail installations of Windows NT will never time-out.

DOS Devices Control Entries
The DosDevices subkey lists the built-in symbolic links to create at startup. The values are stored under this subkey:   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet \Control\Session Manager\DOS Devices Entries in this key have the data type of REG_SZ. The following list shows the default entries under this key.   AUX=\DosDevices\COM1 MAILSLOT=\Device\MailSlot NUL=\Device\Null PIPE=\Device\NamedPipe PRN=\DosDevices\LPT1 TELNET=\Device\Telnet UNC=\Device\Mup

Environment Control Entries
The Environment subkey defines environment variables that the system creates and that are used by Windows NT Logon and Program Manager.

CAUTION: Use extreme care in changing these entry values. If the operating system cannot find the files specified for a subsystem, you will not be able to run non-Windows NT applications.

The Registry path for these values is:   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet \Control\Session Manager\Environment

ComSpec REG_EXPAND_SZ Filename
Default: %systemRoot%\SYSTEM32\CMD.EXE Defines the path and filename for the Windows NT command interpreter (the equivalent of MS-DOS COMMAND.COM).

Os2LibPath REG_EXPAND_SZ Filename
Default: %systemRoot%\SYSTEM32\os2\dll Defines the path for the Microsoft OS/2 version 1.x library.

Path REG_EXPAND_SZ Filename
Default: %systemRoot%\SYSTEM32; %SystemRoot% Defines the path variable for Windows NT logon and Program Manager.

Windir REG_EXPAND_SZ Filename
Default: %systemRoot%\SYSTEM32\CMD.EXE Defines the path for the executable for WOW, as used by Windows NT logon and Program Manager.

FileRenameOperations Entries
Entries for the FileRenameOperation support the MoveFileEx delayed-rename and delayed-delete capabilities. Entries are stored under this Registry path: <pre class="fixed_text">  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet \Control\Session Manager\FileRenameOperations These entries should be maintained only by the system.

KnownDLLs Control Entries
The KnownDlls key defines the set of DLLs that are first searched during system startup. In general these are system DLLs that are loaded from disk into a section of memory and are checked for integrity. These DLLs consume some resources, even if no application loads them. These appear as separate entries under this Registry path: <pre class="fixed_text">  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet \Control\Session Manager\KnownDLLs

driverName REG_SZ DLL Filename
This series of entries defines a driver name and the corresponding DLL filename. The following shows the default entries: <pre class="fixed_text">  advapi32=advapi32.dll                olecli32=olecli32.dll comdlg32=comdlg32.dll               olesvr32=olesvr32.dll crtdll=crtdll.dll                   rpcrt4=rpcrt4.dll DllDirectory=%SystemRoot%\system32  shell32=shell32.dll gdi32=gdi32.dll                     user32=user32.dll kernel32=kernel32.dll               version=version.dll lz32=lz32.dll

Memory Management Control Entries
The Memory Management subkey defines paging options under the following Registry path: <pre class="fixed_text">  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet \Control\Session Manager\Memory Management The paging file parameters should be defined by using the System icon in Control Panel and choosing the Virtual Memory button.

IoPageLockLimit REG_DWORD Number of bytes
<pre class="fixed_text">Default: 512K Specifies the limit of the number of bytes that can be locked for I/O operations. When this value is 0, the system uses the default (512K). The maximum value is about the equivalent of physical memory minus pad, which is 7 MB for a small system and grows as the amount of memory grows. For a 64 MB system, pad is about 16 MB; for a 512 MB system, pad is about 64 MB.

LargeSystemCache REG_DWORD Number
<pre class="fixed_text">Default: 0 Specifies, for a nonzero value, that the system favor the system-cache working set rather than the processes working set. Set this value by choosing the Windows NT Advanced Server installation base.

NonPagedPoolSize REG_DWORD Number of bytes
<pre class="fixed_text">Default: 0 Specifies the size of nonpaged pool in bytes. When this value is 0, the system uses the default size (based on physical memory). The maximum amount is about 80 percent of physical memory.

PagedPoolSize REG_DWORD 0 to 128 MB
<pre class="fixed_text">Default:  0x3000000 (32 MB) Specifies the size of paged pool in bytes. When this value is 0, the system uses the default size (32 MB). See also the entry for RegistrySizeLimit at the beginning of this section.

PagingFiles REG_MULTI_SZ System_Paging_Files
<pre class="fixed_text">Default: C:\pagefile.sys 27 Specifies page file information set by choosing the System icon in Control Panel.

Subsystem Startup Control Entries
The following is the Registry path for the subsystem settings established at startup: <pre class="fixed_text">  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet \Control\Session Manager\SubSystems These values should only be maintained by the system. You should not need to manually define these settings.

Debug REG_EXPAND_SZ Names
<pre class="fixed_text">Default: (no value)

Optional REG_MULTI_SZ Subsystem names
<pre class="fixed_text">Default: Os2 Posix Defines subsystems that are only loaded when the user starts an application that requires this subsystem.

Os2 REG_EXPAND_SZ Path and filename
<pre class="fixed_text">Default: %SystemRoot%\system32\os2ss.exe Defines the path to the executable file used to start the Microsoft OS/2 version 1.x subsystem.

Posix REG_EXPAND_SZ Path and filename
<pre class="fixed_text">Default: %SystemRoot%\system32\psxss.exe Defines the path to the executable file used to start the POSIX subsystem. (There are no additional POSIX entries in the Registry.)

Required REG_MULTI_SZ Name
<pre class="fixed_text">Default: Debug Windows

Windows REG_EXPAND_SZ Path and filename
<pre class="fixed_text">Default: %SystemRoot%\system32\csrss.exe ObjectDirectory=\Windows SharedSection=1024,3072 Windows=On SubSystemType=Windows ServerDll=basesrv,1 ServerDll=winsrv:GdiServerDllInitialization,4 ServerDll=winsrv:UserServerDllInitialization,3 ServerDll=winsrv:ConServerDllInitialization,2 ServerDll=mmsndsrv,5 ProfileControl=Off MaxRequestThreads=16 Defines the path to the executable file used to start the Win32 subsystem.

Reference: "The Windows NT Resource Kit for Operating System Version 3.1".

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