Red Hat LINUX 7.2 - OFFICIAL LINUX CUSTOMIZATION GUIDE Guida di Installazione Scaricare il pdf (Pagina 57)

Chapter 3. Boot Process, Init, and Shutdown 57

• The existence of prompt tells LILO to show you whatever is referenced in the message line. While

it is not recommended that you remove the prompt line, if you do remove it, you can still get a

prompt by holding down the [Shift] key while your machine starts to boot.

• timeout=50 sets the amount of time that LILO will wait for user input before proceeding with

booting the default line entry. This is measured in tenths of a second, with 50 as the default.

• message=/boot/message refers to the screen that LILO displays to let you select the operating

system or kernel to boot.

• lba32 describes the hard disk geometry to LILO. Another common entry here is linear. You

should not change this line unless you are very aware of what you are doing. Otherwise, you could

put your system in an unbootable state.

• default=linux refers to the default operating system for LILO to boot from the options listed

below this line. The name linux refers to the label line below in each of the boot options.

• image=/boot/vmlinuz-2.4.0-0.43.6 speciﬁes the linux kernel to boot with this particular

boot option.

• label=linux names the operating system option in the LILO screen. In this case, it is also the

name referred to by the default line.

• initrd=/boot/initrd-2.4.0-0.43.6.img refers to the initial ram disk image that is used at

boot time to actually initialize and start the devices that makes booting the kernel possible. The

initial ram disk is a collection of machine-speciﬁc drivers necessary to operate a SCSI card, hard

drive, or any other device needed to load the kernel. You should never try to share initial ram disks

between machines.

• read-only speciﬁes that the root partition (see the root line below) is read-only and cannot be

altered during the boot process.

• root=/dev/hda5 tells LILO what disk partition to use as the root partition.

LILO then shows the Red Hat Linux initial screen with the different operating systems or kernels it

has been conﬁgured to boot. If you only have Red Hat Linux installed and have not changed anything

in /etc/lilo.conf, you will only see linux as an option. If you install SMP kernel support, you

will see linux-up as an option. If you have set up LILO to boot other operating systems as well, this

screen is your chance to select what operating system will boot. Use your arrow keys to highlight the

operating system and press [Enter]

If you would like to have a command prompt to enter commands to LILO, press [Ctrl]-[X]. LILO

displays a LILO: prompt on the screen and waits for input from the user. (The amount of time LILO

waits is set by the timeout line in the /etc/lilo.conf ﬁle.) If your /etc/lilo.conf is set

to give LILO a choice of operating systems, at this time you could type in the label for whichever

operating system you want to boot.

If LILO is booting Linux, it ﬁrst loads the kernel into memory, which is a vmlinuz ﬁle (for example,

vmlinuz-2.4.0-xx) located in the /boot/ directory. Then the kernel passes control to init.

Warning

Do not remove the /initrd/ directory for any reason. Removing this directory will cause your system

to fail to boot with a kernel panic error message.

At this point, with the kernel loaded into memory and operational, Linux is already started, although

at a very basic level. However, with no applications utilizing the kernel and with no ability for the user

to provide meaningful input to the system, not much can be done with it. The init program solves

this problem by bringing up the various services that allow the system to perform its particular role.

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Red Hat LINUX 7.2 - OFFICIAL LINUX CUSTOMIZATION GUIDE Guida di Installazione Pagina 57

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