Boot non EFI MS-DOS Windows 7 partition with grub2-gpt

As an IT administrator, learning how to boot a non-EFI MS-DOS/Windows 7 partition with GRUB2 on a GPT disk can be a valuable skill. This method is useful when a single disk contains multiple operating systems, or when an older version of Windows is needed for compatibility reasons.

When setting up a non-EFI MS-DOS/Windows 7 partition on a GPT disk, the first step is to install GRUB2. GRUB2 is an open source boot loader that can be used to boot multiple operating systems from a single disk. It is the successor to the GRUB Legacy boot loader, and is the default boot loader for many Linux distributions.

Once GRUB2 has been installed, the next step is to configure it to boot the non-EFI MS-DOS/Windows 7 partition. This can be done in two ways; either manually editing the GRUB2 configuration file, or using the GRUB2 command line.

The first method involves editing the GRUB2 configuration file. This file is typically located in the /etc/default/grub directory. The file contains various settings that can be adjusted to boot the non-EFI MS-DOS/Windows 7 partition. The settings that need to be adjusted are the ‘GRUB_DEFAULT’ and ‘GRUB_TIMEOUT’ settings.

The ‘GRUB_DEFAULT’ setting is used to determine which operating system will be booted by default. To boot the non-EFI MS-DOS/Windows 7 partition, this setting should be set to ‘saved’. This tells GRUB2 to boot the operating system that was last used.

The ‘GRUB_TIMEOUT’ setting is used to determine how long GRUB2 will wait before automatically booting the default operating system. This setting should be set to a value that is long enough to allow users to select the non-EFI MS-DOS/Windows 7 partition from the GRUB2 menu.

The second method involves using the GRUB2 command line. This can be done by pressing the ‘c’ key when the GRUB2 menu is displayed. This will open the GRUB2 command line, which can be used to enter various commands. To boot the non-EFI MS-DOS/Windows 7 partition, the ‘set root=’ command should be used to set the root device to the non-EFI MS-DOS partition, followed by the ‘linux’ and ‘initrd’ commands to load the necessary files.

Once the non-EFI MS-DOS/Windows 7 partition has been configured, it can be booted by selecting it from the GRUB2 menu or by setting it as the default operating system with the ‘GRUB_DEFAULT’ setting. When booting the non-EFI MS-DOS/Windows 7 partition, it is important to remember that it will not be able to access the other partitions on the disk.

In summary, booting a non-EFI MS-DOS/Windows 7 partition with GRUB2 on a GPT disk is a relatively straightforward process. The main steps involve installing GRUB2, configuring the GRUB2 settings, and using the GRUB2 command line to boot the non-EFI MS-DOS/Windows 7 partition. With these steps in place, IT administrators should be able to successfully boot a non-EFI MS-DOS/Windows 7 partition from a GPT disk.