This article provides an overview of boot options in Windows. You'll learn about the key components of the boot process, including:

• The Windows Boot Manager, operating system loader, and resume loader.
• The Boot Configuration Data (BCD) store where boot options are kept.
• The BCDEdit tool used to modify boot options.

During development, you can use this information to configure boot options for debugging, testing, and troubleshooting your driver.

Boot Loading Architecture

Windows uses three primary components to load the operating system quickly and securely:

• Windows Boot Manager: Starts the system, displays the boot menu to the user, and loads the selected operating system loader.
• Windows operating system loader: Resides in the Windows partition, takes over the boot process, and loads the operating system.
• Windows resume loader: Resumes the system from hibernation.

The Windows Boot Manager is generic, while the system-specific boot loaders are optimized for the OS they load. The Boot Manager passes boot parameters to the selected loader, which then completes the boot process.

For additional detail on the Windows startup process, refer toWindows Internals, published by Microsoft Press.

Boot Configuration Data

Windows stores boot options in the Boot Configuration Data (BCD) store on BIOS-based and EFI-based computers. The BCD store uses GUIDs and names like "Default" to identify boot-related applications.

Key BCD capabilities for driver development:

• Access BCD at run time and during system setup
• Manage BCD remotely for troubleshooting
• Restore BCD from USB media or Startup Repair

For a complete list of BCD boot options, seeBCD Boot Options Reference.

Edit boot options with BCDEdit

To edit boot options in Windows, use BCDEdit (BCDEdit.exe), a command-line tool included in Windows.

Prerequisites

• Administrator privileges on the computer
• BitLocker and Secure Boot disabled or suspended (if enabled)

Alternative tools for editing boot options

• System Configuration utility (MSConfig.exe) - GUI-based boot settings editor
• Advanced Startup settings UI - Built into Windows settings
• Boot Configuration Data WMI Provider - For programmatic changes

Next steps

• Learn BCDEdit commands and syntax
• View all BCD boot options
• Set up boot parameters for debugging