Boot Loader Configuration
In order to boot the 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. GRUB 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.
 | Caution |
|---|
| | 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.
 | Note |
|---|
| | 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. Once 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.
Advanced Boot Loader Configuration
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. 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.
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 which 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.
Rescue Mode
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.
By 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. Once you have
booted using this diskette, type linux rescue
at the boot: prompt.
By booting from a network diskette made from the
bootnet.img or PCMCIA boot diskettes made from
pcmcia.img. Once 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 an explanation of how to specify this information,
see the Section called Preparing for a Network Installation.
For more information, refer to the Official Red Hat Linux Customization Guide.
Alternative Boot Loaders
If you do not wish to use a boot loader, 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
ftp://metalab.unc.edu/pub/Linux/system/boot/dualboot/ |
and associated mirror sites.
- SYSLINUX
SYSLINUX is an MS-DOS program very similar to LOADLIN. It is
also available from
ftp://metalab.unc.edu/pub/Linux/system/boot/loaders/ |
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).
| Note |
|---|
| | Boot loaders such as LOADLIN and System Commander are considered to
be third-party boot loaders and are not supported by Red Hat. |
SMP Motherboards, GRUB, and LILO
This section is specific to SMP motherboards only. SMP, short for
Symmetric Multiprocessing, is a computer architecture providing fast
performance by making multiple CPUs available to complete individual
processes simultaneously (multiprocessing).
If the installation program detects an SMP motherboard on your system,
it will automatically create two boot loader entries.
| Note |
|---|
| | IntelŪ PentiumŪ 4 systems with
hyperthreading will have an SMP kernel installed by default. |
The two GRUB entries will be Red Hat Linux
(kernel version) and
Red Hat Linux (kernel
version-smp). The Red Hat
Linux (kernel version-smp)
will boot by default. However, if you have trouble with the SMP kernel,
you can elect to boot the Red Hat Linux
(kernel version) entry
instead. You will retain all the functionality as before, but you will
only be operating with a single processor.
The two LILO entries will be linux
and linux-up. The
linux entry will boot by
default. However, if you have trouble with the SMP kernel, you can elect
to boot the linux-up entry instead. You
will retain all the functionality as before, but you will only be
operating with a single processor.
