Linux Unleashed, Third Edition:Using LILO





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Removing or Disabling LILO
To prevent LILO from booting the system, the boot sector must be disabled (by using fdisk to change the active partition) or removed completely. Most versions of LILO can be quickly disabled with the following command:


/etc/lilo/lilo -u


If you are using the newer directory structure, substitute the pathname as necessary.

When removing a LILO boot sector in the Master Boot Record of the disk, the MBR must be replaced with another record. If you want to replace the MBR with a DOS MBR from a booted DOS disk, enter the following command:


fdisk /mbr


Because backup copies of the boot sector are created whenever LILO creates a new version, the older versions of the boot sector can be copied back in place (assuming they are still available). For example, to restore the Master Boot Record saved in a file called boot.0800 (800 is the device number of a SCSI drive), issue the following command:


dd if=/etc/lilo/boot.0800 of=/dev/sda bs=446 count=1


If you are using another device, substitute the name of the saved boot file and the device name.

Troubleshooting LILO
LILO displays error messages when it can’t function properly. These error messages should be sufficient to identify the problem. The most common error messages and their solutions are shown in Table 4.4.

Table 4.4.LILO error messages.



Message
Solution



Can’t put the boot sector on logical partition X
LILO attempted to put the boot sector on the correct root file system on a logical partition. MBRs can only boot primary partitions by default. Override with the -b option and an explicit boot partition value or use the configuration variable boot=device.

Got bad geometry
The disk controller (mostly SCSI) doesn’t support automatic geometry detection. Use the file /etc/lilo/disktab to provide the disk parameters.

Invalid partition table, entry X
The sector/head/cylinder and linear addresses of the first sector of the partition don’t match. This usually occurs when an operating system creates partitions not aligned to tracks. Try the fix table option.

First sector doesn’t have a valid boot signature
The first sector of the device doesn’t seem to be a valid boot sector. Check the device name or rerun LILO to install the boot sector.

Cylinder number of too big
A file is located beyond the 1,024th cylinder which LILO can’t access because of BIOS limitations.

XXX doesn’t have a valid LILO signature
XXX was located but isn’t a valid LILO entry. If XXX is the boot sector, you should use the -I option or the install option to install the LILO boot sector.

XXX has an invalid stage code
The entry at XXX is corrupted. Rerun LILO.

Kernel XXX is too big
The kernel is larger than 512 Kb, which LILO can’t handle. Remove some unused drivers and recompile the kernel.

Partition entry not found
The partition is not in the partition table.

Sorry, don’t know how to handle device XXX
LILO can’t determine the disk parameters. Use the file /etc/lilo/disktab to specify them.



Summary
This chapter includes all the information you need to install and use LILO to create your boot sectors for Linux. LILO is quite versatile and can handle several different configurations with ease. It allows you to tailor your installation to boot the best way for your use.

Although LILO is used only when first setting up your Linux system and after kernel changes, you should know the basics of its operation so you know what is happening to your hard disks and their boot sectors. This is especially true when you use other operating systems on the same system. From here, you may want to jump ahead to other chapters:

To start using your Linux system, read Chapter 6, “Getting Started.”
To configure X so you can work with a GUI instead of character-based terminals, see Chapter 22, “Installing and Configuring XFree86.”
To administer your newly installed Linux system, see Chapter 32, “System Administration Basics.”





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