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Session Manager Subsystem, or smss.exe, is a component of the Microsoft Windows NT family of operating systems, starting in Windows NT 3.1. It is executed during the startup process of those operating systems (it is the first user-mode process started by the kernel), at which time it performs the following tasks:

After the boot process is finished, the program resides in memory and can be seen running in the Windows Task Manager. It then waits for either winlogon.exe or csrss.exe to end, at which point Windows will shut down. If the processes do not end in an expected fashion, smss.exe may hang the system, or a bugcheck will occur.[2] It also initiates new user sessions when needed.

The Local Session Manager Service (lsm.exe) sends requests to SMSS through the Asynchronous Local Inter-Process Communication (ALPC) port SmSsWinStationApiPort to start new sessions.

See also


  1. ^ Matt Pietrek (1996). "Poking Around Under the Hood: A Programmer's View of Windows NT 4.0". Microsoft Systems Journal. Archived from the original on November 18, 2012.
  2. ^ a b Microsoft Corporation (2007). "Default Processes in Windows 2000". Microsoft Corporation. Retrieved 2009-06-14.

Further reading