smss.exe is the first user mode process that is started by the Windows kernel (and is therefore sometimes compared to Linux' init). Required under registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\SubSystems. BootExecute under the registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\driverName.