Windows 7 / Getting Started

Session Manager

After all entries that have Boot and Startup data types are processed, the kernel starts the Session Manager (Smss.exe), a user process that continues to run until the operating system is shut down. The Session Manager performs important initialization functions, such as:

  • Creating system environment variables.
  • Starting the kernel-mode portion of the Win32 subsystem (implemented by %SystemRoot%\System32\Win32k.sys), which causes Windows to switch from text mode (used to display the Windows Boot Manager menu) to graphics mode (used to display the Starting Windows logo). Windows-based applications run in the Windows subsystem. This environment allows applications to access operating system functions, such as displaying information to the screen.
  • Starting the user-mode portion of the Win32 subsystem (implemented by %SystemRoot%\System32\Csrss.exe). The applications that use the Windows subsystem are user-mode processes; they do not have direct access to hardware or device drivers. Instead, they have to access Windows APIs to gain indirect access to hardware. This allows Windows to control direct hardware access, improving security and reliability. User-mode processes run at a lower priority than kernel-mode processes. When the operating system needs more memory, it can page to disk the memory used by usermode processes.
  • Starting the Logon Manager (%SystemRoot%\System32\Winlogon.exe).
  • Creating additional virtual memory paging files.
  • Performing delayed rename operations for files specified by the registry entry HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager \PendingFileRenameOperations. For example, you might be prompted to restart the computer after installing a new driver or application so that Windows can replace files that are currently in use.

Session Manager searches the registry for service information contained in the following subkeys:

  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager contains a list of commands to run before loading services. The Autochk.exe tool is specified by the value of the registry entry BootExecute and virtual memory (paging file) settings stored in the Memory Management subkey. Autochk, which is a version of the Chkdsk tool, runs at startup if the operating system detects a file system problem that requires repair before completing the startup process.
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager \SubSystems stores a list of available subsystems. For example, Csrss.exe contains the user-mode portion of the Windows subsystem.

If startup fails during the kernel loading phase after another operating system was installed on the computer, the cause of the problem is likely an incompatible boot loader. Boot loaders installed by versions of Windows prior to Windows Vista cannot be used to start Windows Vista or Windows 7. Use System Recovery to replace startup files with Windows startup files.

Otherwise, if startup fails during the kernel loading phase, use boot logging to isolate the failing feature. Then use safe mode to disable problematic features (if possible) or use System Recovery to replace problematic files. For more information, see the section titled "Startup Troubleshooting Before the Starting Windows Logo Appears" later in this tutorial. If you experience a Stop error during this phase, use the information provided by the Stop message to isolate the failing feature.

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In this tutorial:

  1. Configuring Startup and Troubleshooting Startup Issues
  2. What is New with Windows Startup
  3. Boot Configuration Data
  4. BCD Stores
  5. System Recovery
  6. Windows Boot Performance Diagnostics
  7. Understanding the Startup Process
  8. Power-on Self Test Phase
  9. Initial Startup Phase
  10. Initial Startup Phase for BIOS Computers
  11. Initial Startup Phase for EFI Computers
  12. Windows Boot Manager Phase
  13. Windows Boot Loader Phase
  14. Kernel Loading Phase
  15. Control Sets
  16. Values for the Start Registry Entry
  17. Value Descriptions for Type Entries
  18. Other Registry Entries in the Servicename Subkeys
  19. Session Manager
  20. Logon Phase
  21. Important Startup Files
  22. How to Configure Startup Settings
  23. How to Use the Startup And Recovery Dialog Box
  24. How to Use the System Configuration Tool
  25. How to Use BCDEdit
  26. How to Interpret BCDEdit Output
  27. How to Back Up and Restore Settings
  28. How to Change the Default Operating System Entry
  29. How to Change the Boot Menu Time-Out
  30. How to Change the Order of Boot Manager Menu Items
  31. How to Create an Entry for Another Operating System
  32. How to Remove a Boot Entry
  33. How to View and Update Global Debugger Settings
  34. How to Remove the Windows 7 Boot Loader
  35. How to Configure a User Account to Automatically Log On
  36. How to Disable the Windows Startup Sound
  37. How to Speed Up the Startup Process
  38. The Process of Troubleshooting Startup
  39. Startup Troubleshooting Before the Starting Windows Logo Appears
  40. How to Start the System Recovery Tools
  41. How to Run Startup Repair
  42. How to Use BootRec.exe
  43. How to Diagnose Hardware Problems
  44. How to Use System Restore
  45. How to Manually Repair the Boot Sector
  46. How to Manually Update the BCD Registry File
  47. How to Manually Replace Files
  48. How to Reinstall Windows
  49. Startup Troubleshooting After the Starting Windows Logo Appears
  50. How to Restore the Last Known Good Configuration
  51. How to Enable Boot Logging
  52. How to Start in Safe Mode
  53. How to Identify Failing Drivers and Services
  54. How to Analyze Startup Problems in Safe Mode
  55. Event Viewer (Eventvwr.msc)
  56. System Information
  57. Error Reporting Service
  58. How to Use Device Manager to View or Change Resources
  59. How to Analyze Boot Logs
  60. How to Roll Back Drivers
  61. How to Temporarily Disable a Service
  62. Troubleshooting Startup Problems After Logon
  63. How to Temporarily Disable Startup Applications and Processes
  64. How to Disable Startup Applications Using the Shift Key
  65. How to Disable Startup Programs Using the System Configuration Utility
  66. How to Disable Startup Applications Configured Using Group Policy or Logon Scripts
  67. How to Permanently Disable Startup Applications and Processes
  68. Manually Remove the Entry