Overview of the boot.ini File

The boot.ini file is a text file that stores boot options for x86-based computers running NT-based Windows operating systems.

When the computer starts, the operating system loader, Ntldr, reads the boot.ini file and displays the entries for each operating system in the boot menu. Then Ntldr loads the selected operating system in accordance with the settings in boot.ini.

The boot.ini file is located at the root of the system partition. By default, on NTFS drives, the system, hidden, archived, and read-only attributes are set to protect the file, but members of the Administrators group can change these attributes. The file attributes do not affect the operation of Ntldr.

The boot.ini file has two main sections:

• The boot loader section contains options that apply to all operating systems installed on the computer. It includes timeout, the boot menu timeout value, and default, the location of the default operating system.

  The following sample shows the boot loader section of a boot.ini file.

  [boot loader]
  timeout=3
  default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
  

• The operating systems section contains one or more boot entries for each operating system or bootable program installed on the computer.

  A boot entry is a set of options that defines a load configuration for an operating system or bootable program. Formerly called operating system entries, the name is changed to indicate that this section can now include entries for bootable program and devices, such as the Windows Recovery Console, as well as those for operating systems.

  The following sample shows the operating systems section of a boot.ini file on a computer with two operating systems, Microsoft Windows XP and Microsoft Windows 2000. It has two boot entries, one for each operating system.

  [operating systems]
  multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
  multi(0)disk(0)rdisk(0)partition(2)\WINNT="Microsoft Windows 2000 Professional" /fastdetect
  

Each boot entry includes the following elements:

• The location of the operating system. The boot.ini file uses the Advanced Risk Computing (ARC) naming convention to display the path to the disk partition and directory where the operating system resides. For example, multi(0)disk(0)rdisk(0)partition(1)\WINDOWS.
• A friendly name for the boot entry (for example,"Microsoft Windows XP Professional") that represents the boot entry in the boot menu. The friendly name is surrounded by quotation marks and.represents the boot entry in the boot menu.
• Boot entry parameters, or boot parameters, are commands to the boot loader that enable, disable, and configure features of the operating system. The boot parameters look like command-line parameters, each beginning with a forward slash (/), such as /fastdetect. You can have zero or more boot parameters on each boot entry.

  For a list of boot parameters relevant to driver test and debugging, see the Boot Parameter Reference.

You can have multiple boot entries for the same operating system, each with a different set of boot parameters. Windows creates a standard boot entry when you install the operating system, and you can create additional, customized entries for an operating system by editing the boot.ini file.

For a detailed description of the boot.ini file on x86-based systems, including a complete list of supported boot.ini file parameters, see Reviewing and Correcting Boot.ini Settings on x86-based Systems in the Windows XP Professional Resource Kit Documentation.