A software boot loader is used to start Red Hat Linux on your computer. It can also start other operating systems, such as Windows. If you are using a Red Hat Linux software boot loader (GRUB or LILO), the boot loader will be detected automatically.
Figure 3-3. Upgrade Boot Loader Configuration
On the Boot Loader Configuration Screen, your options are:
Update boot loader configuration — Choose this option to keep your current boot loader configuration (GRUB or LILO depending on what you have currently installed) and have updates applied.
Skip boot loader updating — Choose this option if you do not want to make any changes to your current boot loader configuration. If you are using a third-party boot loader, you should skip updating your boot loader.
Create new boot loader configuration — Choose this option if you want to create a new boot loader for your system. If you currently have LILO and want to switch to GRUB, or if you have been using boot diskettes to boot your Red Hat Linux system and want to use a software boot loader such as GRUB or LILO, you will want to create a new boot loader configuration (see the “Creating a New Boot Loader Configuration” section later in this chapter for more information).
After making your selection, click Next to continue.
To boot your system without a boot diskette, you usually need to install a boot loader. A boot loader is the first software program that runs when a computer starts; it is responsible for loading and transferring control to the operating system kernel software. The kernel in turn initializes the rest of the operating system.
The installation program provides two boot loaders for you to choose from, GRUB and LILO:
GRUB (GRand Unified Bootloader), which is installed by default, is a very powerful boot loader that can load a variety of free operating systems, as well as proprietary operating systems with chain-loading (the mechanism for loading unsupported operating systems by loading another boot loader, such as DOS or Windows).
LILO (LInux LOader) is a versatile boot loader for Linux. It does not depend on a specific file system, can boot Linux kernel images from floppy diskettes and hard disks, and can even boot other operating systems.
If you do not want to install GRUB as your boot loader, click Change boot loader. You can then choose to install LILO or choose not to install a boot loader at all.
If you already have a boot loader that can boot Linux and do not want to overwrite your current boot loader, or if you plan to boot the system using boot diskettes, choose Do not install a boot loader by clicking on the Change boot loader button.
If you choose not to install GRUB or LILO for any reason, you will not be able to boot the system directly, and you will need to use another boot method (such as a boot diskette). Use this option only if you are sure you have another way of booting the system!
Every bootable partition is listed, including partitions used by other operating systems. The partition holding your the system's root file system will have a label of Red Hat Linux (for GRUB) or linux (for LILO). Other partitions may also have boot labels. If you would like to add or change the boot label for other partitions that have been detected by the installation program, click once on the partition to select it. Once selected, you can change the boot label by clicking the Edit button.
Select Default beside the preferred boot partition to choose your default bootable OS. You will not be able to move forward in the installation unless you choose a default boot image.
The Label column lists what you must enter at the boot prompt, in non-graphical boot loaders, in order to boot the desired operating system. After you have loaded the GRUB boot screen, use the arrow keys to choose a boot label or type e for edit. You will be presented with a list of items in the configuration file for the boot label you have selected. At the graphical LILO screen, press Ctrl-x to exit to the boot: prompt. If you forget the boot labels defined on your system, you can always press Tab at the prompt to display a list of defined boot labels.
Boot loader passwords provide a security mechanism in an environment where physical access to your server is available.
If you are installing a boot loader, you should create a password to protect your system. Without a boot loader password, users with access to your system can pass options to the kernel, which can compromise your system security. With a boot loader password in place, the password must first be entered in order to select any non-standard boot options.
If you choose to use a boot loader password to enhance your system security, be sure to select the checkbox labeled Use a boot loader password. Once selected, enter a password and confirm it.
To configure more advance boot loader options, such as changing the drive order or passing options to the kernel, be sure Configure advanced boot loader options is selected before clicking Next.
Now that you have chosen which boot loader to install, you can also determine where you want the boot loader to be installed. You may install the boot loader in one of two places:
The master boot record (MBR) — This is the recommended place to install a boot loader, unless the MBR already starts another operating system loader, such as System Commander. The MBR is a special area on your hard drive that is automatically loaded by your computer's BIOS, and is the earliest point at which the boot loader can take control of the boot process. If you install it in the MBR, when your machine boots, GRUB (or LILO) will present a boot prompt. You can then boot Red Hat Linux or any other operating system that you have configured the boot loader to boot.
The first sector of your boot partition — This is recommended if you are already using another boot loader on your system (Windows NT/2000/XP include boot loaders). In this case, your other boot loader will take control first. You can then configure that boot loader to start GRUB (or LILO), which will then boot Red Hat Linux.
Figure 3-5. Boot Loader Installation
If your system will use only Red Hat Linux, you should choose the MBR. For systems with Windows 95/98, you should also install the boot loader to the MBR so that it can boot both operating systems.
Click the Change Drive Order button if you would like to rearrange the drive order. Changing the drive order may be useful if you have multiple SCSI adapters or both SCSI and IDE adapters and want to boot from the SCSI device.
The Force LBA32 (not normally required) option allows you to exceed the 1024 cylinder limit for the /boot partition. If you have a system that supports the LBA32 extension for booting operating systems above the 1024 cylinder limit and you want to place your /boot partition above cylinder 1024, you should select this option.
If you wish to add default options to the boot command, enter them into the Kernel parameters field.
Any options you enter will be passed to the Linux kernel every time it boots.
If you need to use rescue mode, there are several options available to you:
Using the CD-ROM to boot, type linux rescue at the boot: prompt.
Booting your system from an installation boot diskette made from the boot.img image. This method requires that the Red Hat Linux CD-ROM #1 be inserted as the rescue image or that the rescue image be on the hard drive as an ISO image. After you have booted using this diskette, type linux rescue at the boot: prompt.
Booting from a network diskette made from the bootnet.img or PCMCIA boot diskette made from pcmcia.img. After you have booted using this diskette, type linux rescue at the boot: prompt. You can only do this if your network connection is working. You will need to identify the network host and transfer type.
For more information on Rescue Mode, see Appendix A.
If you do not wish to use the GRUB or LILO boot loaders, you have several alternatives:
Boot diskette — You can use the boot diskette created by the installation program (if you create one).
LOADLIN — You can load Linux from MS-DOS. Unfortunately, this requires a copy of the Linux kernel (and an initial RAM disk, if you have a SCSI adapter) to be available on an MS-DOS partition. The only way to accomplish this is to boot your Red Hat Linux system using some other method (for example, from a boot diskette) and then copy the kernel to an MS-DOS partition. LOADLIN is available from
and associated mirror sites.
SYSLINUX — SYSLINUX is an MS-DOS program very similar to LOADLIN. It is available from
and associated mirror sites.
Commercial boot loaders — You can load Linux using commercial boot loaders. For example, System Commander and Partition Magic are able to boot Linux (but still require GRUB or LILO to be installed in your Linux root partition).
Boot loaders such as LOADLIN and System Commander are considered to be third-party boot loaders and are not supported by Red Hat.