LILO - Generic Boot Loader for Linux ("LInux LOader") by Werner Almesberger
===========================================================================

Important: The file INCOMPAT contains vital (in)compatibility information
           for this release of LILO. Read it before proceeding.

Installing boot loaders is inherently dangerous. Be sure to have some means
to boot your system from a different media if you install LILO on your hard
disk.


There is also a LaTeX version of this document in the "doc" directory.
It is much easier nicer to read than pure ASCII.


Installation
------------

Please read the file INCOMPAT for compatibility notes.

The installation procedure is described in the section "Normal first-time
installation". Please read "Booting basics" for the whole story.

*** QUICK INSTALLATION ***

    If you want to install LILO on your hard disk and if you don't want
    to use all its features, you can use the quick installation script.
    Read QuickInst for details.


 
 LILO is a versatile boot loader for Linux. It does not depend on a 
specific file system, can boot Linux kernel images from floppy disks and 
from hard disks and can even boot other operating systems.*

  *  PC/MS-DOS, DR DOS, OS/2, 386BSD, SCO UNIX, Unixware, ...

One of up to sixteen different images can be selected at boot time. Various 
parameters, such as the root device, can be set independently for each 
kernel. LILO can even be used as the master boot record.

This document introduces the basics of disk organization and booting, 
continues with an overview of common boot techniques and finally describes 
installation and use of LILO in greater detail. The troubleshooting section 
at the end describes diagnostic messages and contains suggestions for most 
problems that have been observed in the past.

Please read the sections about installation and configuration if you're 
already using an older version of LILO. This distribution is accompanied by 
a file named INCOMPAT that describes further incompatibilities to older 
versions.

For the impatient: there is a quick-installation script to create a simple 
but quite usable installation. See section "Quick installation" for 
details.

But wait ... here are a few easy rules that will help you avoiding most 
problems people experience with LILO:

  - _Don't panic._ If something doesn't work, try to find out what is 
    wrong, try to verify your assumption and only then attempt to fix it. 
  - Read the documentation. Especially if what the system does doesn't 
    correspond to what you think it should do. 
  - Make sure you have an emergency boot disk, that you know how to use it, 
    and that it is always kept up to date. 
  - Run /sbin/lilo _whenever_ the kernel or any part of LILO, including its 
    configuration file, has changed. 
  - If using LILO as the MBR, de-install it _before_ performing a 
    destructive upgrade and/or erasing your Linux partitions. 
  - Don't trust setup scripts. Always verify the /etc/lilo.conf they create 
    before booting. 
  - If using a big disk, be prepared for inconveniences: you may have to 
    use the LINEAR option. 


Introduction
============

The following sections describe how PCs boot in general and what has to be 
known when booting Linux and using LILO in particular.


Disk organization
-----------------

When designing a boot concept, it is important to understand some of the 
subtleties of how PCs typically organize disks. The most simple case are 
floppy disks. They consist of a boot sector, some administrative data (FAT 
or super block, etc.) and the data area. Because that administrative data 
is irrelevant as far as booting is concerned, it is regarded as part of the 
data area for simplicity.

            +---------------------------+
            |Boot sector|               |
            |-----------+               |
            |                           |
            |         Data area         |
            |                           |
            |                           |
            +---------------------------+

The entire disk appears as one device (e.g. /dev/fd0) on Linux.

The MS-DOS boot sector has the following structure:

                    +------------------------+
              0x000 |Jump to the program code|
                    |------------------------|
              0x003 |                        |
                    |    Disk parameters     |
                    |                        |
                    |------------------------|
        0x02C/0x03E |                        |
                    |      Program code      |
                    |                        |
                    |                        |
                    |------------------------|
              0x1FE | Magic number (0xAA55)  |
                    +------------------------+

LILO uses a similar boot sector, but it does not contain the disk 
parameters part. This is no problem for Minix, Ext2 or similar file 
systems, because they don't look at the boot sector, but putting a LILO 
boot sector on an MS-DOS file system would make it inaccessible for MS-DOS.

Hard disks are organized in a more complex way than floppy disks. They 
contain several data areas called partitions. Up to four so-called primary 
partitions can exist on an MS-DOS hard disk. If more partitions are needed, 
one primary partition is used as an extended partition that contains 
several logical partitions.

The first sector of each hard disk contains a partition table, and an 
extended partition and _each_ logical partition contains a partition table 
too.

        +--------------------------------------------+
        | Partition table                  /dev/hda  |
        | +------------------------------------------|
        | | Partition 1                    /dev/hda1 |
        | |                                          |
        | |------------------------------------------|
        | | Partition 2                    /dev/hda2 |
        | |                                          |
        +--------------------------------------------+

The entire disk can be accessed as /dev/hda, /dev/hdb, /dev/sda, etc. The 
primary partitions are /dev/hda1 ... /dev/hda4.

        +--------------------------------------------+
        | Partition table                  /dev/hda  |
        | +------------------------------------------|
        | | Partition 1                    /dev/hda1 |
        | |                                          |
        | |------------------------------------------|
        | | Partition 2                    /dev/hda2 |
        | |                                          |
        | |------------------------------------------|
        | | Extended partition             /dev/hda3 |
        | | +----------------------------------------|
        | | | Extended partition table               |
        | | |----------------------------------------|
        | | | Partition 3                  /dev/hda5 |
        | | |                                        |
        | | |----------------------------------------|
        | | | Extended partition table               |
        | | |----------------------------------------|
        | | | Partition 4                  /dev/hda6 |
        | | |                                        |
        +--------------------------------------------+

This hard disk has two primary partitions and an extended partition that 
contains two logical partitions. They are accessed as /dev/hda5 ...

Note that the partition tables of logical partitions are not accessible as 
the first blocks of some devices, while the main partition table, all boot 
sectors and the partition tables of extended partitions are.

Partition tables are stored in partition boot sectors. Normally, only the 
partition boot sector of the entire disk is used as a boot sector. It is 
also frequently called the master boot record (MBR).

                    +------------------------+
              0x000 |                        |
                    |      Program code      |
                    |                        |
                    |                        |
                    |------------------------|
              0x1BE |    Partition table     |
                    |                        |
                    |------------------------|
              0x1FE | Magic number (0xAA55)  |
                    +------------------------+

The LILO boot sector is designed to be usable as a partition boot sector. 
(I.e. there is room for the partition table.) Therefore, the LILO boot 
sector can be stored at the following locations:

  - boot sector of a Linux floppy disk. (/dev/fd0, ...) 
  - MBR of the first hard disk. (/dev/hda, ...) 
  - boot sector of a primary Linux file system partition on the first hard 
    disk. (/dev/hda1, ...) 
  - partition boot sector of an extended partition on the first hard disk. 
    (/dev/hda1, ...)* 

  *  Most FDISK-type programs don't believe in booting from an extended 
    partition and refuse to activate it. LILO is accompanied by a simple 
    program (activate) that doesn't have this restriction. Linux fdisk also 
    supports activating extended partitions.

It _can't_ be stored at any of the following locations:

  - boot sector of a non-Linux floppy disk or primary partition. 
  - a Linux swap partition. 
  - boot sector of a logical partition in an extended partition.* 
  - on the second hard disk. (Unless for backup installations, if the 
    current first disk will be removed or disabled, or if some other boot 
    loader is used, that is capable of loading boot sectors from other 
    drives.) 

  *  LILO can be forced to put the boot sector on such a partition by using 
    the  -b  option or the BOOT variable. However, only few programs that 
    operate as master boot records support booting from a logical 
    partition.

LILO typically doesn't detect attempts to put its boot sector at an invalid 
location.


Booting basics
--------------

When booting from a floppy disk, the first sector of the disk, the 
so-called boot sector, is loaded. That boot sector contains a small program 
that loads the respective operating system. MS-DOS boot sectors also 
contain a data area, where disk and file system parameters (cluster size, 
number of sectors, number of heads, etc.) are stored.

When booting from a hard disk, the very first sector of that disk, the 
so-called master boot record (MBR) is loaded. This sector contains a loader 
program and the partition table of the disk. The loader program usually 
loads the boot sector, as if the system was booting from a floppy.

Note that there is no functional difference between the MBR and the boot 
sector other than that the MBR contains the partition information but 
doesn't contain any file system-specific information (e.g. MS-DOS disk 
parameters).

The first 446 (0x1BE) bytes of the MBR are used by the loader program. They 
are followed by the partition table, with a length of 64 (0x40) bytes. The 
last two bytes contain a magic number that is sometimes used to verify that 
a given sector really is a boot sector.

There is a large number of possible boot configurations. The most common 
ones are described in the following sections.


MS-DOS alone
- - - - - -

        +-------------------------------------------------------+
        | Master Boot Record    Boot sector    Operating system |
        |-------------------------------------------------------|
        | DOS-MBR ------------> MS-DOS ------> COMMAND.COM      |
        +-------------------------------------------------------+

This is what usually happens when MS-DOS boots from a hard disk: the 
DOS-MBR determines the active partition and loads the MS-DOS boot sector. 
This boot sector loads MS-DOS and finally passes control to COMMAND.COM. 
(This is greatly simplified.)


BOOTLIN*
- - - - 

  *  A more recent program called LOADLIN uses the same approach. Those who 
    wish to use this method of booting are advised to use LOADLIN instead 
    of BOOTLIN.

    +------------------------------------------------------------+
    | Master Boot Record    Boot sector    Operating system      |
    |------------------------------------------------------------|
    | DOS-MBR ------------> MS-DOS ------> COMMAND.COM           |
    |                                 ---> BOOTLIN ------> Linux |
    +------------------------------------------------------------+

A typical BOOTLIN setup: everything happens like when booting MS-DOS, but 
in CONFIG.SYS or AUTOEXEC.BAT, BOOTLIN is invoked. Typically, a program 
like BOOT.SYS is used to choose among configuration sections in CONFIG.SYS 
and AUTOEXEC.BAT. This approach has the pleasant property that no boot 
sectors have to be altered.

Please refer to the documentation accompanying the package for installation 
instructions and further details.


LILO started by DOS-MBR
- - - - - - - - - - - -

        +-------------------------------------------------------+
        | Master Boot Record    Boot sector    Operating system |
        |-------------------------------------------------------|
        | DOS-MBR ------------> LILO --------> Linux            |
        |                  ---> other OS                        |
        +-------------------------------------------------------+

This is a "safe" LILO setup: LILO is booted by the DOS-MBR. No other boot 
sectors have to be touched. If the other OS (or one of them, if there are 
several other operating systems being used) should be booted without using 
LILO, the other partition has to be marked "active" with fdisk or activate.

Installation: 

  - install LILO with its boot sector on the Linux partition. 
  - use fdisk or activate to make that partition active. 
  - reboot. 

Deinstallation: 

  - make a different partition active. 
  - install whatever should replace LILO or Linux. 


Several alternate branches
- - - - - - - - - - - - -

    +------------------------------------------------------------+
    | Master Boot Record    Boot sector    Operating system      |
    |------------------------------------------------------------|
    | DOS-MBR ------------> MS-DOS ------> COMMAND.COM           |
    |                                 ---> BOOTLIN ------> Linux |
    |                  ---> LILO --------> Linux                 |
    |                                 ---> MS-DOS --- ...        |
    +------------------------------------------------------------+

An extended form of the above setup: the MBR is not changed and both 
branches can either boot Linux or MS-DOS. (LILO could also boot any other 
operating system.)


LILO started by BOOTACTV*
- - - - - - - - - - - - -

  *  Other, possibly better known boot switchers, e.g. OS/2 Bootmanager 
    operate in a similar way. The installation procedures typically vary.

        +-------------------------------------------------------+
        | Master Boot Record    Boot sector    Operating system |
        |-------------------------------------------------------|
        | BOOTACTV -----------> LILO --------> Linux            |
        |                  ---> other OS                        |
        +-------------------------------------------------------+

Here, the MBR is replaced by BOOTACTV (or any other interactive boot 
partition selector) and the choice between Linux and the other operating 
system(s) can be made at boot time. This approach should be used if LILO 
fails to boot the other operating system(s).*

  *  And the author would like to be notified if booting the other 
    operating system(s) doesn't work with LILO, but if it works with an 
    other boot partition selector.

Installation: 

  - boot Linux. 
  - make a backup copy of your MBR on a floppy disk, e.g.
     dd if=/dev/hda of=/fd/MBR bs=512 count=1 
  - install LILO with the boot sector on the Linux partition. 
  - install BOOTACTV as the MBR, e.g.
     dd if=bootactv.bin of=/dev/hda bs=446 count=1 
  - reboot. 

Deinstallation: 

  - boot Linux. 
  - restore the old MBR, e.g.
     dd if=/MBR of=/dev/hda bs=446 count=1
     or FDISK /MBR under MS-DOS. 

If replacing the MBR appears undesirable and if a second Linux partition 
exists (e.g. /usr, _not_ a swap partition), BOOTACTV can be merged with the 
partition table and stored as the "boot sector" of that partition. Then, 
the partition can be marked active to be booted by the DOS-MBR.

Example:

# dd if=/dev/hda of=/dev/hda3 bs=512 count=1
# dd if=bootactv.bin of=/dev/hda3 bs=446 count=1

_WARNING:_ Whenever the disk is re-partitioned, the merged boot sector on 
that "spare" Linux partition has to be updated too.


LILO alone
- - - - -

            +----------------------------------------+
            | Master Boot Record    Operating system |
            |----------------------------------------|
            | LILO ---------------> Linux            |
            |                  ---> other OS         |
            +----------------------------------------+

LILO can also take over the entire boot procedure. If installed as the MBR, 
LILO is responsible for either booting Linux or any other OS. This approach 
has the disadvantage, that the old MBR is overwritten and has to be 
restored (either from a backup copy, with FDISK /MBR on recent versions of 
MS-DOS or by overwriting it with something like BOOTACTV) if Linux should 
ever be removed from the system.

You should verify that LILO is able to boot your other operating system(s) 
before relying on this method.

Installation: 

  - boot Linux. 
  - make a backup copy of your MBR on a floppy disk, e.g.
     dd if=/dev/hda of=/fd/MBR bs=512 count=1 
  - install LILO with its boot sector as the MBR. 
  - reboot. 

Deinstallation: 

  - boot Linux. 
  - restore the old MBR, e.g.
     dd if=/fd/MBR of=/dev/hda bs=446 count=1 

If you've installed LILO as the master boot record, you have to explicitly 
specify the boot sector (configuration variable BOOT=...) when updating the 
map. Otherwise, it will try to use the boot sector of your current root 
partition, which may even work, but will probably leave your system 
unbootable.


Names
- - -

The following names have been used to describe boot sectors or parts of 
operating systems:

  "DOS-MBR"  is the original MS-DOS MBR. It scans the partition table for a 
    partition that is marked "active" and loads the boot sector of that 
    partition. Programs like MS-DOS' FDISK, Linux fdisk or activate 
    (accompanies LILO) can change the active marker in the partition table. 
  "MS-DOS"  denotes the MS-DOS boot sector that loads the other parts of 
    the system (IO.SYS, etc.). 
  "COMMAND.COM"  is the standard command interpreter of MS-DOS. 
  "BOOTLIN" and "LOADLIN"  are programs that load a Linux kernel image from 
    an MS-DOS partition into memory and execute it. They are usually 
    invoked from CONFIG.SYS and used in combination with a CONFIG.SYS 
    configuration switcher, like BOOT.SYS.* 
  "LILO"  can either load a Linux kernel or the boot sector of any other 
    operating system. It has a first stage boot sector that loads the 
    remaining parts of LILO from various locations.** 
  "BOOTACTV"  permits interactive selection of the partition from which the 
    boot sector should be read. If no key is pressed within a given 
    interval, the partition marked active is booted. BOOTACTV is included 
    in the pfdisk package. There are also several similar programs, like 
    PBOOT and OS-BS.*** 

  *  BOOTLIN is available for anonymous FTP from
     nic.funet.fi:/pub/OS/Linux/tools/bootlin.zip
     LOADLIN is available for anonymous FTP from
     sunsite.unc.edu:/pub/Linux/system/Linux-boot/lodlin15.tgz
     BOOT.SYS is available for anonymous FTP from
     sunsite.unc.edu:/pub/Linux/system/Linux-boot/boot142.zip or
     nic.funet.fi:/pub/OS/Linux/tools/boot142.zip

  **  LILO can be found in
     tsx-11.mit.edu:/pub/linux/packages/lilo/lilo.<n>.tar.gz
     sunsite.unc.edu:/pub/Linux/system/Linux-boot/lilo/lilo.<n>.tar.gz
     nic.funet.fi:/pub/OS/Linux/tools/lilo.<n>.tar.gz

  ***  pfdisk is available for anonymous FTP from
     sunsite.unc.edu:/pub/Linux/utils/disk-management/pfdisk.tar.Z or
     nic.funet.fi:/pub/OS/Linux/tools/pfdisk.tar.Z
     PBOOT can be found in
     nic.funet.fi:/pub/OS/Linux/tools/pboot.zip


Choosing the "right" boot concept
-----------------------------------

Although LILO can be installed in many different ways, the choice is 
usually limited by the present setup and therefore, typically only a small 
number of configurations which fit naturally into an existing system 
remains.

The configuration file /etc/lilo.conf for the examples could look like 
this:

boot = /dev/hda2
compact
image = /vmlinuz
image = /vmlinuz.old
other = /dev/hda1
  table = /dev/hda
  label = msdos

It installs a Linux kernel image (/vmlinuz), an alternate Linux kernel 
image (/vmlinuz.old) and a chain loader to boot MS-DOS from /dev/hda1. The 
option COMPACT on the second line instructs the map installer to optimize 
loading.

In all examples, the names of the IDE-type hard disk devices (/dev/hda...) 
are used. Everything applies to other disk types (e.g. SCSI disks; 
/dev/sda...) too.


BIOS restrictions
- - - - - - - - -

Nowadays, an increasing number of systems is equipped with comparably large 
disks or even with multiple disks. At the time the disk interface of the 
standard PC BIOS has been designed (about 15 years ago), such 
configurations were apparently considered to be too unlikely to be worth 
supporting.

The most common BIOS restrictions that affect LILO are the limitation to 
two hard disks and the inability to access more than 1024 cylinders per 
disk. LILO can detect both conditions, but in order to solve the underlying 
problems, manual intervention is necessary.

The drive limit does not exist in every BIOS. Some modern motherboards and 
disk controllers are equipped with a BIOS that supports more (typically 
four) disk drives. When attempting to access the third, fourth, etc. drive, 
LILO prints a warning message but continues. Unless the BIOS really 
supports more than two drives, the system will _not_ be able to boot in 
that case.*

  *  If only "unimportant" parts of the system are located on the "high" 
    drives, some functionality may be available.

The cylinder limit is a very common problem with IDE disks. There, the 
number of cylinders typically exceeds 1024 if the drive has a capacity of 
more than 504 MB. Many SCSI driver BIOSes present the disk geometry in a 
way that makes the limit occur near 1 GB. Modern disk controllers may even 
push the limit up to about 8 GB. All cylinders beyond the 1024th are 
inaccessible for the BIOS. LILO detects this problem and aborts the 
installation (unless the LINEAR option is used, see section "Global 
options").

Note that large partitions that only partially extend into the "forbidden 
zone" are still in jeopardy even if they appear to work at first, because 
the file system does not know about the restrictions and may allocate disk 
space from the area beyond the 1024th cylinder when installing new kernels. 
LILO therefore prints a warning message but continues as long as no 
imminent danger exists.

There are four approaches of how such problems can be solved: 

  - use of a different partition which is on an accessible disk and which 
    does not exceed the 1024 cylinder limit. If there is only a DOS 
    partition which fulfills all the criteria, that partition can be used 
    to store the relevant files. (See section "/boot on a DOS partition".) 
  - rearranging partitions and disks. This is typically a destructive 
    operation, so care should be taken to make good backups. 
  - if the system is running DOS, LOADLIN can be used instead of LILO. 
  - if all else fails, installation of a more capable BIOS, a different 
    controller or a different disk configuration. 

LILO depends on the BIOS to load the following items: 

  - /boot/boot.b 
  - /boot/map (created when running /sbin/lilo) 
  - all kernels 
  - the boot sectors of all other operating systems it boots 
  - the startup message, if one has been defined 

Normally, this implies that the Linux root file system should be in the 
"safe" area. However, it is already sufficient to put all kernels into 
/boot and to either mount a "good" partition on /boot or to let /boot be a 
symbolic link pointing to or into such a partition.

See also /usr/src/linux/drivers/block/README.ide for a detailed description 
of problems with large disks.


One disk, Linux on a primary partition
- - - - - - - - - - - - - - - - - - -

If at least one primary partition of the first hard disk is used as a Linux 
file system (/, /usr, etc. but _not_ as a swap partition), the LILO boot 
sector should be stored on that partition and it should be booted by the 
original master boot record or by a program like BOOTACTV.

            +--------------------------+
            | MBR            /dev/hda  |
            | +------------------------|
            | | MS-DOS       /dev/hda1 |
            | |------------------------|
        --> | | Linux /      /dev/hda2 |
            +--------------------------+

In this example, the BOOT variable could be omitted, because the boot 
sector is on the root partition.


One disk, Linux on a logical partition
- - - - - - - - - - - - - - - - - - -

If no primary partition is available for Linux, but at least one logical 
partition of an extended partition on the first hard disk contains a Linux 
file system, the LILO boot sector should be stored in the partition sector 
of the extended partition and it should be booted by the original master 
boot record or by a program like BOOTACTV.

            +--------------------------+
            | MBR            /dev/hda  |
            | +------------------------|
            | | MS-DOS       /dev/hda1 |
            | |------------------------|
        --> | | Extended     /dev/hda2 |
            | | +----------------------|
            | | | Linux      /dev/hda5 |
            | | |----------------------|
            | | | ...        /dev/hda6 |
            +--------------------------+

Because many disk partitioning programs refuse to make an extended 
partition (in our example /dev/hda2) active, you might have to use 
activate, which comes with the LILO distribution.

OS/2 BootManager should be able to boot LILO boot sectors from logical 
partitions. The installation on the extended partition itself is not 
necessary in this case.


Two disks, Linux (at least partially) on the first disk
- - - - - - - - - - - - - - - - - - - - - - - - - - - -

This case is equivalent to the configurations where only one disk is in the 
system. The Linux boot sector resides on the first hard disk and the second 
disk is used later in the boot process.

Only the location of the boot sector matters - everything else 
(/boot/boot.b, /boot/map, the root file system, a swap partition, other 
Linux file systems, etc.) can be located anywhere on the second disk.


Two disks, Linux on second disk, first disk has an extended partition
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

If there is no Linux partition on the first disk, but there is an extended 
partition, the LILO boot sector can be stored in the partition sector of 
the extended partition and it should be booted by the original master boot 
record or by a program like BOOTACTV.

                 FIRST DISK                     SECOND DISK
        +--------------------------+    +--------------------------+
        | MBR            /dev/hda  |    | MBR            /dev/hdb  |
        | +------------------------|    | +------------------------|
        | | MS-DOS       /dev/hda1 |    | | Linux        /dev/hdb1 |
        | |------------------------|    | |------------------------|
    --> | | Extended     /dev/hda2 |    | | ...          /dev/hdb2 |
        | | +----------------------|    | |                        |
        | | | ...        /dev/hda5 |    | |                        |
        | | |----------------------|    | |                        |
        | | | ...        /dev/hda6 |    | |                        |
        +--------------------------+    +--------------------------+

The program activate, that accompanies LILO, may have to be used to set the 
active marker on an extended partition, because MS-DOS' FDISK and some 
older version of Linux fdisk refuse to do that. (Which is generally a good 
idea.)


Two disks, Linux on second disk, first disk has no extended partition
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

If there is neither a Linux partition nor an extended partition on the 
first disk, then there's only one place left, where a LILO boot sector 
could be stored: the master boot record.

In this configuration, LILO is responsible for booting all other operating 
systems too.

                 FIRST DISK                     SECOND DISK
        +--------------------------+    +--------------------------+
    --> | MBR            /dev/hda  |    | MBR            /dev/hdb  |
        | +------------------------|    | +------------------------|
        | | MS-DOS       /dev/hda1 |    | | Linux        /dev/hdb1 |
        | |------------------------|    | |------------------------|
        | | ...          /dev/hda2 |    | | ...          /dev/hdb2 |
        +--------------------------+    +--------------------------+

You should back up your old MBR before installing LILO and verify that LILO 
is able to boot your other operating system(s) before relying on this 
approach.

The line boot = /dev/hda2 in /etc/lilo.conf would have to be changed to 
boot = /dev/hda in this example.


More than two disks
- - - - - - - - - -

On systems with more than two disks, typically only the first two can be 
accessed. The configuration choices are therefore the same as with two 
disks.

When attempting to access one of the extra disks, LILO displays a warning 
message ( Warning: BIOS drive 0x<number> may not be accessible ) but does 
not abort. This is done in order to allow the lucky few whose BIOS (or 
controller-BIOS) does support more than two drives to make use of this 
feature. By all others, this warning should be considered a fatal error.

Note that the two disks restriction is only imposed by the BIOS. Linux 
normally has no problems using all disks once it is booted.


/boot on a DOS partition
- - - - - - - - - - - -

Recent kernels support all the functions LILO needs to map files also on 
MS-DOS (or UMSDOS) file systems. Since DOS partitions tend to occupy 
exactly the places where BIOS restrictions (see section "BIOS 
restrictions") are invisible, they're an ideal location for /boot if the 
native Linux file systems can't be used because of BIOS problems.

In order to accomplish this, the DOS partition is mounted read-write, a 
directory (e.g. /dos/linux) is created, all files from /boot are moved to 
that directory, /boot is replaced by a symbolic link to it, the kernels are 
also moved to the new directory, their new location is recorded in 
/etc/lilo.conf, and finally /sbin/lilo is run.

From then on, new kernels must always be copied into that directory on the 
DOS partition before running /sbin/lilo, e.g. when recompiling a kernel, 
the standard procedure changes from

# make zlilo

to

# make zImage
# mv /dos/linux/vmlinuz /dos/linux/vmlinuz.old
# mv arch/i386/boot/zImage /dos/linux/vmlinuz
# /sbin/lilo

_WARNING:_ De-fragmenting such a DOS partition is likely to make Linux or 
even the whole system unbootable. Therefore, the DOS partition should 
either not be de-fragmented, or a Linux boot disk should be prepared (and 
tested) to bring up Linux and to run /sbin/lilo after the 
de-fragmentation.*

  *  Setting the "system" attribute from DOS on the critical files (e.g. 
    everything in C:\LINUX) may help to protect them from being rearranged. 
    However, the boot floppy should still be ready, just in case.


The boot prompt
===============

Immediately after it's loaded, LILO checks whether one of the following is 
happening:

  - any of the [Shift], [Control] or [Alt] keys is being pressed. 
  - [CapsLock] or [ScrollLock] is set. 

If this is the case, LILO displays the boot: prompt and waits for the name 
of a boot image (i.e. Linux kernel or other operating system). Otherwise, 
it boots the default boot image* or - if a delay has been specified - waits 
for one of the listed activities until that amount of time has passed.

  *  The default boot image is either the first boot image, the image 
    specified with the DEFAULT variable, or the image that has been 
    selected at the boot prompt.

At the boot prompt, the name of the image to boot can be entered. Typing 
errors can be corrected with [BackSpace], [Delete], [Ctrl U] and [Ctrl X]. 
A list of known images can be obtained by pressing [?] (on the US keyboard) 
or [Tab].

If [Enter] is pressed and no file name has been entered, the default image 
is booted.


Boot command-line options
-------------------------

LILO is also able to pass command-line options to the kernel. Command-line 
options are words that follow the name of the boot image and that are 
separated by spaces.

Example:

boot: linux single root=200


Standard options
- - - - - - - -

The 1.1.90 kernel recognizes the options  debug ,  no387 ,  no-hlt ,  
ramdisk=<size> ,  reserve=<base>,<size>,... ,  root=<device> ,  ro , and  
rw , and all current init programs also recognize the option  single . The 
options  lock  and  vga  are processed by the boot loader itself. Boot 
command-line options are always case-sensitive.

 single  boots the system in single-user mode. This bypasses most system 
initialization procedures and directly starts a root shell on the console. 
Multi-user mode can typically be entered by exiting the single-user shell 
or by rebooting.

 root=<device>  changes the root device. This overrides settings that may 
have been made in the boot image and on the LILO command line. <device> is 
either the hexadecimal device number or the full path name of the device, 
e.g. /dev/hda3.*

  *  The device names are hard-coded in the kernel. Therefore, only the 
    "standard" names are supported and some less common devices may not be 
    recognized. In those cases, only numbers can be used.

 reserve=<base>,<size>,...  reserves IO port regions. This can be used to 
prevent device drivers from auto-probing addresses where other devices are 
located, which get confused by the probing.

 ro  instructs the kernel to mount the root file system read-only.  rw  
mounts it read-write. If neither  ro  nor  rw  is specified, the setting 
from the boot image is used.

 no-hlt  avoids executing a  HLT  instructions whenever the system is idle.  
HLT  normally significantly reduces power consumption and therefore also 
heat dissipation of the CPU, but may not work properly with some clone 
CPUs.  no387  disables using the hardware FPU even if one is present.

 debug  enables more verbose console logging.

 vga=<mode>  alters the VGA mode set at startup. The values  normal ,  
extended ,  ask  or a decimal number are recognized. (See also "Booting 
kernel images from a file".)

Finally,  lock  stores the current command-line as the default 
command-line, so that LILO boots the same image with the same options 
(including  lock ) when invoked the next time.


Device-specific options
- - - - - - - - - - - -

There is also a large number of options to specify certain characteristics 
(e.g. IO and memory addresses) of devices. The 1.1.90 kernel understands 
the following device options (if the corresponding devices are included):  
ether ,  max_scsi_luns ,  hd ,  hda ,  hdb , hdc ,  hdd ,  st ,  bmouse ,  
st0x ,  tmc8xx ,  t128 ,  pas16 ,  ncr5380 ,  aha152x ,  aha1542 ,  aha274x 
,  buslogic ,  xd ,  mcd ,  aztcd ,  sound ,  sbpcd , and  cdu31a . The 
usage of these options is  <option>=<number>,... . Please consult the 
corresponding FAQs and HOWTOs for details.


Other options
- - - - - - -

Options of the type  <variable>=<value>  which are neither standard options 
nor device-specific options, cause the respective variables to be set in 
the environment passed to init. The case of the variable name is preserved. 
(I.e. it's not automatically converted to upper case.)

Note that environment variables passed to init are typically available in 
system initialization scripts (e.g. /etc/rc.local), but they're not visible 
from ordinary login sessions, because the login program removes them from 
the user's environment.


Repeating options
- - - - - - - - -

The effect of repeating boot command-line options depends on the options.* 
There are three possible behaviours:

  *  Options are frequently repeated when a string defined with APPEND or 
    LITERAL is prepended to the parameters typed in by the user. Also, LILO 
    implicitly prepends the options  ramdisk ,  ro ,  root , or  rw  when 
    RAMDISK, READ-ONLY, READ-WRITE, or ROOT, respectively, are set in the 
    configuration file. ( lock  and  vga  are handled by a different 
    internal mechanism.)

Options that only enable or disable a certain functionality can be repeated 
any number of times.  debug ,  lock ,  no-hlt , and  no387  fall into this 
category.

Other options change a global setting whenever they appear, so only the 
value or presence of the last option matters. The antagonists  ro  and  rw  
are such options. Also,  ramdisk ,  root , and  vga  work this way. 
Example:  ro rw  would mount the root file system read-write.

Finally, when  reserve  and many device-specific options are repeated, each 
occurrence has its own meaning, e.g.  hd=... hd=...  would configure two 
hard disks, and  reserve=0x300,8 reserve=0x5f0,16  would reserve the ranges 
0x300 to 0x307 and 0x5f0 to 0x5ff (which is equivalent to writing  
reserve=0x300,8,0x5f0,16 ).


Implicit options
- - - - - - - -

LILO always passes the string  BOOT_IMAGE=<name>  to the kernel, where 
<name> is the name by which the kernel is identified (e.g. the label). This 
variable can be used in /etc/rc to select a different behaviour, depending 
on the kernel.

When booting automatically, the word  auto  is also passed on the command 
line. This can be used by init to suppress interactive prompts in the boot 
phase.


Boot image selection
--------------------

The details of selecting the boot image are somewhat complicated. The 
following tables illustrate them. First, if neither PROMPT is set nor a 
shift key is being pressed:

Externally  Command   |  Auto-  Booted image             
 provided   line in   |  matic                           
cmd. line* map file** | boot***                          
---------------------------------------------------------
    No         No     |   Yes   Default image            
   Yes         -      |   Yes   Specified by external    
                      |         command line             
    No        Yes     |   Yes   Specified by command line
                      |         in map file              
       

  *  Externally provided command lines could be used to add front-ends to 
    LILO. They would pass the respective command string to LILO, which 
    would then interpret it like keyboard input. This feature is currently 
    not used.

  **  This command line is set by invoking the map installer with the  -R  
    option or by using the boot command-line option  lock .

  ***  I.e. the keyword  auto  is added.

If PROMPT is not set and a shift key is being pressed:

 Input  Empty  Extern. Cmd.l. | Auto- Booted image         
timeout cmd.l. cmd.l.  in map | matic                      
                        file  | boot                       
-----------------------------------------------------------
  No      No      -      -    |  No   Specified by the user
  No     Yes      -      -    |  No   Default image        
  Yes    n/a      -      -    |  Yes  Default image        

Finally, if the configuration variable PROMPT is set:

 Input  Empty  Extern. Cmd.l. | Auto- Booted image         
timeout cmd.l. cmd.l.  in map | matic                      
                        file  | boot                       
-----------------------------------------------------------
  No      No     No      No   |  No   Specified by the user
  No     Yes     No      No   |  No   Default image        
  Yes    n/a     No      No   |  Yes  Default image        
  n/a    n/a     Yes     -    |  Yes  Specified by external
                              |       command line         
  n/a    n/a     No     Yes   |  Yes  Specified by command 
                              |       line in map file     

Note that LILO pauses for the amount of time specified in DELAY when at the 
end of a default command line. The automatic boot can then be interrupted 
by pressing a shifting key.

The default image is the first image in the map file or the image specified 
with the DEFAULT variable. However, after an unsuccessful boot attempt, the 
respective image becomes the default image.


Map installer
=============

The map installer program /sbin/lilo updates the boot sector and creates 
the map file. If the map installer detects an error, it terminates 
immediately and does not touch the boot sector and the map file.

Whenever the map installer updates a boot sector, the original boot sector 
is copied to /boot/boot.<number>, where <number> is the hexadecimal device 
number. If such a file already exists, no backup copy is made. Similarly, a 
file  /boot/part.<number>  is created if LILO modifies the partition table. 
(See "General per-image options".)


Command-line options
--------------------

The LILO map installer can be invoked in the following ways:


Show current installation
- - - - - - - - - - - - -

The currently mapped files are listed. With  -v , also many parameters are 
shown.

  /sbin/lilo [ -C <config_file> ] [ -q ] [ -m <map_file> ] [ -v ... ]  

   -C <config_file>    
     Specifies the configuration file that is used by the map installer 
    (see section "Configuration"). If  -C  is omitted, /etc/lilo.conf is 
    used. 
   -m <map_file>    
     Specifies an alternate map file. See also sections "Options 
    corresponding to configuration variables" and "Global options". 
   -q    
     Lists the currently mapped files. 
   -v ...    
     Increase verbosity. See also sections "Options corresponding to 
    configuration variables" and "Global options". 


Create or update map
- - - - - - - - - -

A new map is created for the images described in the configuration file 
/etc/lilo.conf and they are registered in the boot sector.

  /sbin/lilo [ -C <config_file> ] [ -b <boot_device> ] [ -c ] [ -l ] [ -i 
    <boot_sector> ] [ -f <disk_tab> ] [ -m <map_file> ] [ -d <delay> ] [ -v 
    ... ] [ -t ] [ -s <save_file> | -S <save_file> ] [ -P fix | -P ignore ] 
    [ -r <root_dir> ]  

   -b <boot_device>    
     Specifies the boot device. See also sections "Options corresponding to 
    configuration variables" and "Global options". 
   -c    
     Enables map compaction. See also sections "Options corresponding to 
    configuration variables" and "Global options". 
   -C <config_file>    
     Specifies an alternate configuration file. See also section "Show 
    current installation". 
   -d <delay>    
     Sets the delay before LILO boots the default image. Note that the 
    delay is specified in _tenths_ of a second. See also sections "Options 
    corresponding to configuration variables" and "Global options". 
   -f <disk_tab>    
     Specifies a disk parameter table file. See also sections "Options 
    corresponding to configuration variables" and "Global options". 
   -i <boot_sector>    
     Specifies an alternate boot file. See also sections "Options 
    corresponding to configuration variables" and "Global options". 
   -l    
     Enables linear sector addresses. See also sections "Options 
    corresponding to configuration variables" and "Global options". 
   -m <map_file>    
     Specifies an alternate map file. See also sections "Options 
    corresponding to configuration variables" and "Global options". 
   -P <mode>    
     Specifies how invalid partition table entries should be handled. See 
    also sections "Options corresponding to configuration variables" and 
    "Global options". 
   -r <root_directory>    
     Chroots to the specified directory before doing anything else. This is 
    useful when running the map installer while the normal root file system 
    is mounted somewhere else, e.g. when recovering from an installation 
    failure with a recovery disk. The  -r  option is implied if the 
    environment variable  ROOT  is set.* The current directory is changed 
    to the new root directory, so using relative paths may not work. 
   -s <save_file>    
     Specifies an alternate boot sector save file. See also sections 
    "Options corresponding to configuration variables" and "Global 
    options". 
   -S <save_file>    
     Like  -s , but overwrites old save file. 
   -t    
     Test only. This performs the entire installation procedure except 
    replacing the map file, writing the modified boot sector and fixing 
    partition tables. This can be used in conjunction with the  -v  option 
    to verify that LILO will use sane values. 
   -v ...    
     Increase verbosity. See also sections "Options corresponding to 
    configuration variables" and "Global options". 

  *  E.g. if your root partition is mounted on /mnt, you can update the map 
    by simply running  ROOT=/mnt /mnt/sbin/lilo 


Change default command line
- - - - - - - - - - - - - -

Changes LILO's default command line. See also section "Boot image 
selection".

  /sbin/lilo [ -C <config_file> ] [ -m <map_file> ] [ -R [ <word> ... ] ]  

   -C <config_file>    
     Specifies an alternate configuration file. See also section "Show 
    current installation". 
   -m <map_file>    
     Specifies an alternate map file. See also sections "Options 
    corresponding to configuration variables" and "Global options". 
   -R <word ...>    
     Stores the specified words in the map file. The boot loader uses those 
    words as the default command line when booting the next time. That 
    command line is removed from the map file by the boot loader by 
    overwriting the sector immediately after reading it. The first word has 
    to be the name of a boot image. If  -R  is not followed by any words, 
    the current default command line in the map file is erased.* An error 
    message is issued and a non-zero exit code is returned if the command 
    line is not accepted. 

  *   -R  is typically used in reboot scripts, e.g.
     #!/bin/sh
     cd /
     if /sbin/lilo -R "$*"; then
         echo | shutdown -r now
     fi


Kernel name translation
- - - - - - - - - - - -

Determines the path of the kernel.

  /sbin/lilo [ -C <config_file> ] -I <name> [ <options> ]  

   -C <config_file>    
     Specifies an alternate configuration file. See also section "Show 
    current installation". 
   -I <name> [ <options> ]    
     Translates the specified label name to the path of the corresponding 
    kernel image and prints that path on standard output. This can be used 
    to synchronize files that depend on the kernel (e.g. the ps database). 
    The image name can be obtained from the environment variable  
    BOOT_IMAGE . An error message is issued and a non-zero exit code is 
    returned if no matching label name can be found. The existence of the 
    image file is verified if the option character  v  is added. 


De-installation
- - - - - - - -

Restores the boot sector that was used before the installation of LILO. 
Note that this option only works properly if LILO's directories (e.g. 
/boot) have not been touched since the first installation. See also section 
"LILO de-installation".

  /sbin/lilo [ -C <config_file> ] [ -s <save_file> ] -u | -U [ 
    <boot_device> ]  

   -C <config_file>    
     Specifies an alternate configuration file. See also section "Show 
    current installation". 
   -s <save_file>    
     Specifies an alternate boot sector save file. See also sections 
    "Options corresponding to configuration variables" and "Global 
    options". 
   -u [ <device_name> ]    
     Restores the backup copy of the specified boot sector. If no device is 
    specified, the value of the boot variable is used. If this one is also 
    unavailable, LILO uses the current root device. The name of the backup 
    copy is derived from the device name. The -s option or the backup 
    variable can be used to override this. LILO validates the backup copy 
    by checking a time stamp. 
   -U [ <device_name> ]    
     Like -u, but does not check the time stamp. 


Print version number
- - - - - - - - - -

  /sbin/lilo -V  

   -V    
     Print the version number and exit. 


Options corresponding to configuration variables
- - - - - - - - - - - - - - - - - - - - - - - -

There are also many command-line options that correspond to configuration 
variables. See section "Global options" for a description.

Command-line option | Configuration variable    
------------------------------------------------
-b <boot_device>    | boot=<boot_device>        
-c                  | compact                   
-d <tsecs>          | delay=<tsecs>             
-D <name>           | default=<name>            
-i <boot_sector>    | install=<boot_sector>     
-f <disktab_file>   | disktab=<disktab_file>    
-l                  | linear                    
-m <map_file>       | map=<map_file>            
-P fix              | fix-table                 
-P ignore           | ignore-table              
-s <backup_file>    | backup=<backup_file>      
-S <backup_file>    | force-backup=<backup_file>
-v ...              | verbose=<level>           


Configuration
-------------

The configuration information is stored in the file /etc/lilo.conf and 
consists of variable assignments.


Syntax
- - -

The following syntax rules apply:

  - flag variables consist of a single word and are followed by whitespace 
    or the end of the file. 
  - string variables consist of the variable name, optional whitespace, an 
    equal sign, optional whitespace, the value and required whitespace, or 
    the end of the file. 
  - a non-empty sequence of blanks, tabs, newlines and comments counts as 
    whitespace. 
  - variable names are case-insensitive. Values are usually case-sensitive, 
    but there are a few exceptions. (See below.) 
  - tabs and newlines are special characters and may not be part of a 
    variable name or a value. The use of other control characters and 
    non-ASCII characters is discouraged. 
  - blanks and equal signs may only be part of a variable name or a value 
    if they are escaped by a backslash or if the value is embedded in 
    double quotes. An equal sign may not be the only character in a name or 
    value. 
  - an escaped tab is converted to an escaped blank. An escaped newline is 
    removed from the input stream. An escaped backslash (i.e. two 
    backslashes) is converted to a backslash. Inside quoted strings, only 
    double quotes and backslashes can be escaped. 
  - comments begin with a number sign and end with the next newline. All 
    characters (including backslashes) until the newline are ignored. 


Global options
- - - - - - -

/etc/lilo.conf begins with a possibly empty global options section. Many 
global options can also be set from the command line, but storing permanent 
options in the configuration file is more convenient.

The following global options are recognized:

  BACKUP=<backup_file>  Copy the original boot sector to <backup_file> 
    (which may also be a device, e.g. /dev/null) instead of 
    /boot/boot.<number> 
  BOOT=<boot_device>  Sets the name of the device (e.g. a hard disk 
    partition) that contains the boot sector. If BOOT is omitted, the boot 
    sector is read from (and possibly written to) the device that is 
    currently mounted as root. 
  COMPACT  Tries to merge read requests for adjacent sectors into a single 
    read request. This drastically reduces load time and keeps the map 
    smaller. Using COMPACT is especially recommended when booting from a 
    floppy disk. 
  DEFAULT=<name>  Uses the specified image as the default boot image. If 
    DEFAULT is omitted, the image appearing first in the configuration file 
    is used. 
  DELAY=<tsecs>  Specifies the number of tenths of a second LILO should 
    wait before booting the first image. This is useful on systems that 
    immediately boot from the hard disk after enabling the keyboard. LILO 
    doesn't wait if DELAY is omitted or if DELAY is set to zero. 
  DISK=<device_name>  Defines non-standard parameters for the specified 
    disk. See section "Disk geometry" for details. 
  DISKTAB=<disktab_file>  Specifies the name of the disk parameter table 
    (see section "Disk parameter table"). The map installer looks for 
    /etc/disktab if DISKTAB is omitted. The use of disktabs is discouraged; 
    see section "Disk geometry" for a vastly superior approach. 
  FIX-TABLE  allows LILO to adjust 3D addresses in partition tables. Each 
    partition entry contains a 3D (sector/head/cylinder) and a linear 
    address of the first and the last sector of the partition. If a 
    partition is not track-aligned and if certain other operating systems 
    (e.g. PC/MS-DOS or OS/2) are using the same disk, they may change the 
    3D address. LILO can store its boot sector only on partitions where 
    both address types correspond. LILO re-adjusts incorrect 3D start 
    addresses if FIX-TABLE is set.

     _WARNING:_ This does not guarantee that other operating systems may 
    not attempt to reset the address later. It is also possible that this 
    change has other, unexpected side-effects. The correct fix is to 
    re-partition the drive with a program that does align partitions to 
    tracks. Also, with some disks (e.g. some large EIDE disks with address 
    translation enabled), under some circumstances, it may even be 
    unavoidable to have conflicting partition table entries. 
  FORCE-BACKUP=<backup_file>  Like BACKUP, but overwrite an old backup copy 
    if it exists. BACKUP=<backup_file> is ignored if FORCE-BACKUP appears 
    in the same configuration file. 
  IGNORE-TABLE  tells LILO to ignore corrupt partition tables. 
  INSTALL=<boot_sector>  Install the specified file as the new boot sector. 
    If INSTALL is omitted, /boot/boot.b is used as the default. 
  LINEAR  Generate linear sector addresses instead of sector/head/cylinder 
    addresses. Linear addresses are translated at run time and do not 
    depend on disk geometry. Note that boot disks may not be portable if 
    LINEAR is used, because the BIOS service to determine the disk geometry 
    does not work reliably for floppy disks. When using LINEAR with large 
    disks, /sbin/lilo may generate references to inaccessible disk areas 
    (see section "BIOS restrictions"), because 3D sector addresses are not 
    known before boot time. 
  LOCK  Enables automatic recording of boot command lines as the defaults 
    for the following boots. This way, LILO "locks" on a choice until it is 
    manually overridden. 
  MAP=<map_file>  Specifies the location of the map file. If MAP is 
    omitted, a file /boot/map is used. 
  MESSAGE=<message_file>  specifies a file containing a message that is 
    displayed before the boot prompt. No message is displayed while waiting 
    for a shifting key after printing "LILO ". In the message, the  FF  
    character ([Ctrl L]) clears the local screen. The size of the message 
    file is limited to 65535 bytes. The map file has to be rebuilt if the 
    message file is changed or moved. 
  NOWARN  Disables warnings about possible future dangers. 
  OPTIONAL  makes all images optional. (See below.) 
  PASSWORD=<password>  sets a password for all images. (See below.) 
  PROMPT  forces entering the boot prompt without expecting any prior 
    key-presses. Unattended reboots are impossible if PROMPT is set and 
    TIMEOUT isn't. 
  RESTRICTED  relaxes the password protection. (See below.) 
  SERIAL=<parameters>  enables control from a serial line. The specified 
    serial port is initialized and LILO is accepting input from it and from 
    the PC's keyboard. Sending a break on the serial line corresponds to 
    pressing a shift key on the console in order to get LILO's attention. 
    All boot images should be password-protected if the serial access is 
    less secure than access to the console, e.g. if the line is connected 
    to a modem. The parameter string has the following syntax:
      <port>,<bps><parity><bits> 
     The components <bps>, <parity> and <bits> can be omitted. If a 
    component is omitted, all following components have to be omitted too. 
    Additionally, the comma has to be omitted if only the port number is 
    specified. 

      <port>  the number of the serial port, zero-based. 0 corresponds to 
        COM1 alias /dev/ttyS0, etc. All four ports can be used (if 
        present). 
      <bps>  the baud rate of the serial port. The following baud rates are 
        supported: 110, 150, 300, 600, 1200, 2400, 4800 and 9600 bps. 
        Default is 2400 bps. 
      <parity>  the parity used on the serial line. LILO ignores input 
        parity and strips the 8th bit. The following (upper or lower case) 
        characters are used to describe the parity:  n  for no parity,  e  
        for even parity and  o  for odd parity. 
      <bits>  the number of bits in a character. Only 7 and 8 bits are 
        supported. Default is 8 if parity is "none", 7 if parity is "even" 
        or "odd". 

    If SERIAL is set, the value of DELAY is automatically raised to 20.

     Example: serial=0,2400n8 initializes COM1 with the default parameters. 
  TIMEOUT=<tsecs>  sets a timeout (in tenths of a second) for keyboard 
    input. If no key is pressed for the specified time, the first image is 
    automatically booted. Similarly, password input is aborted if the user 
    is idle for too long. The default timeout is infinite. 
  VERBOSE=<level>  Turns on lots of progress reporting. Higher numbers give 
    more verbose output. If  -v  is additionally specified on the command 
    line, <level> is increased accordingly. The following verbosity levels 
    exist: 

      <0  only warnings and errors are shown 
      0  prints one line for each added or skipped image 
      1  mentions names of important files and devices and why they are 
        accessed. Also displays informational messages for exceptional but 
        harmless conditions and prints the version number. 
      2  displays statistics and processing of temporary files and devices 
      3  displays disk geometry information 
      4  lists sector mappings as they are written into the map file (i.e. 
        after compaction, in a format suitable to pass it to the BIOS) 
      5  lists the mapping of each sector (i.e. before compaction, raw) 

    When using the  -q  option, the levels have a slightly different 
    meaning: 

      0  displays only image names 
      1  also displays all global and per-image settings 
      2  displays the address of the first map sector 

Additionally, the kernel configuration parameters APPEND, RAMDISK, 
READ-ONLY, READ-WRITE, ROOT and VGA can be set in the global options 
section. They are used as defaults if they aren't specified in the 
configuration sections of the respective kernel images. See below for a 
description.

The plethora of options may be intimidating at first, but in "normal" 
configurations, hardly any options but BOOT, COMPACT, DELAY, ROOT, and VGA 
are used.


General per-image options
- - - - - - - - - - - - -

LILO uses the main file name (without its path) of each image specification 
to identify that image. A different name can be used by setting the 
variable LABEL (see the example above). A second name for the same entry 
can be used by specifying the ALIAS=<name> option.

Images are protected by a password if the variable PASSWORD is set. If the 
variable RESTRICTED is set in addition to PASSWORD, a password is only 
required to boot the respective image if parameters are specified on the 
command line (e.g. single). PASSWORD and RESTRICTED can also be set in the 
options section to be the default password and password protection mode for 
all images. Because the configuration file contains unencrypted passwords 
when using PASSWORD, it should only be readable for the super-user.

If an image section contains the variable OPTIONAL (or if that variable is 
set in the options section), the respective image is omitted if its main 
file is not available at map creation time. This is useful to specify test 
kernels that are not always present.


Per-image options for kernels
- - - - - - - - - - - - - - -

Each (kernel or non-kernel) image description begins with a special 
variable (see section "Booting kernel images from a device") which is 
followed by optional variables. The following variables can be used for all 
image descriptions that describe a Linux kernel:

  APPEND=<string>  Appends the options specified in <string> to the 
    parameter line passed to the kernel. This is typically used to specify 
    parameters of hardware that can't be entirely auto-detected, e.g.
     append = "hd=64,32,202" 
  LITERAL=<string>  Like APPEND, but removes all other options (e.g. 
    setting of the root device). Because vital options can be removed 
    unintentionally with LITERAL, this option cannot be set in the global 
    options section. 
  RAMDISK=<size>  specifies the size of the optional RAM disk. A value of 
    zero indicates that no RAM disk should be created. If this variable is 
    omitted, the RAM disk size configured into the boot image is used. 
  READ-ONLY  specifies that the root file system should be mounted 
    read-only. Typically, the system startup procedure re-mounts the root 
    file system read-write later (e.g. after fsck'ing it). 
  READ-WRITE  specifies that the root file system should be mounted 
    read-write. 
  ROOT=<root_device>  specifies the device that should be mounted as root. 
    If the special name CURRENT is used, the root device is set to the 
    device on which the root file system is currently mounted. If the root 
    has been changed with  -r , the respective device is used. If the 
    variable ROOT is omitted, the root device setting contained in the 
    kernel image is used. It can be changed with the rdev program. 
  VGA=<mode>   specifies the VGA text mode that should be selected when 
    booting. The following values are recognized (case is ignored): 

      NORMAL  select normal 80x25 text mode. 
      EXTENDED  select 80x50 text mode. The word EXTENDED can be 
        abbreviated to EXT. 
      ASK  stop and ask for user input (at boot time). 
      <number>  use the corresponding text mode. A list of available modes 
        can be obtained by booting with  vga=ask  and pressing [Enter]. 

    If this variable is omitted, the VGA mode setting contained in the 
    kernel image is used. rdev supports manipulation of the VGA text mode 
    setting in the kernel image. 

If one of RAMDISK, READ-ONLY, READ-WRITE, ROOT, or VGA is omitted in the 
configuration file and the corresponding value in the kernel image is 
changed, LILO or the kernel will use the new value.

It is perfectly valid to use different settings for the same image, because 
LILO stores them in the image descriptors and not in the images themselves.

Example:

image = /vmlinuz
  label = lin-hd
  root = /dev/hda2
image = /vmlinuz
  label = lin-fd
  root = /dev/fd0


Boot image types
----------------

LILO can boot the following types of images: 

  - kernel images from a file. 
  - kernel images from a block device. (E.g. a floppy disk.) 
  - the boot sector of some other operating system. 

The image type is determined by the name of the initial variable of the 
configuration section.

The image files can reside on any media that is accessible at boot time. 
There's no need to put them on the root device, although this certainly 
doesn't hurt.

In the configuration sections of all boot images, the following variables 
are recognized: ALIAS, LABEL, LOCK, OPTIONAL, PASSWORD and RESTRICTED.

In the configuration sections of all kernels (i.e. every boot image type 
except "other operating system"), the following variables are recognized: 
APPEND, LITERAL, RAMDISK, READ-ONLY, READ-WRITE, ROOT and VGA.


Booting kernel images from a file
- - - - - - - - - - - - - - - - -

The image is specified as follows: IMAGE=<name>

Example:

image = /linux


Booting kernel images from a device
- - - - - - - - - - - - - - - - - -

The range of sectors that should be mapped, has to be specified. Either a 
range ( <start>-<end> ) or a start and a distance ( <start>+<number> ) have 
to be specified. <start> and <end> are zero-based. If only the start is 
specified, only that sector is mapped.

The image is specified as follows: IMAGE=<device_name> Additionally, the 
RANGE variable must be set.

Example:

image = /dev/fd0
  range = 1+512


Booting a foreign operating system
- - - - - - - - - - - - - - - - -

LILO can even boot other operating systems, i.e. MS-DOS. To boot an other 
operating system, the name of a loader program, the device or file that 
contains the boot sector and the device that contains the partition table 
have to be specified.

The boot sector is merged with the partition table and stored in the map 
file.

Currently, the loaders chain.b, os2_d.b, any_b.b and any_d.b exist. chain.b 
simply starts the specified boot sector.* os2_d.b can boot OS/2 from the 
second hard disk. any_b.b and any_d.b install resident drivers that swap 
the first and the second floppy or hard disk drive. They can boot any 
operating system from the second hard disk, if it uses only the BIOS. This 
is known to work for PC/MS-DOS.

  *  The boot sector is loaded by LILO's secondary boot loader before 
    control is passed to the code of chain.b.

The image is specified as follows: OTHER=<device_name> or OTHER=<file_name>

The following additional variables are recognized: LOADER, TABLE and 
UNSAFE.

  LOADER=<chain_loader>  specifies the chain loader that should be used. If 
    it is omitted, /boot/chain.b is used. The chain loader must be 
    specified if booting from a device other than the first hard or floppy 
    disk. 
  TABLE=<device>  specifies the device that contains the partition table. 
    LILO does not pass partition information to the booted operating system 
    if this variable is omitted. (Some operating systems have other means 
    to determine from which partition they have been booted. E.g. MS-DOS 
    usually stores the geometry of the boot disk or partition in its boot 
    sector.) Note that /sbin/lilo must be re-run if a partition table 
    mapped referenced with TABLE is modified. 
  UNSAFE  do not access the boot sector at map creation time. This disables 
    some sanity checks, including a partition table check. If the boot 
    sector is on a fixed-format floppy disk device, using UNSAFE avoids the 
    need to put a readable disk into the drive when running the map 
    installer. UNSAFE and TABLE are mutually incompatible. 

Example:

other = /dev/hda2
  label = os2
  table = /dev/hda


Disk geometry
-------------

For floppies and most hard disks, LILO can obtain the disk geometry 
information from the kernel. Unfortunately, there are some exotic disks or 
adapters which may either not supply this information or which may even 
return incorrect information.

If no geometry information is available, LILO reports either the error
  geo_query_dev HDIO_GETGEO (dev 0x<number>) 
 or
  Device 0x<number>: Got bad geometry <sec>/<hd>/<cyl> 

If incorrect information is returned, booting may fail in several ways, 
typically with a partial "LILO" banner message. In this document, that is 
called a "geometry mismatch".

The next step should be to attempt setting the LINEAR configuration 
variable or the  -l  command-line option. If this doesn't help, the entire 
disk geometry has to be specified explicitly. Note that LINEAR doesn't 
always work with floppy disks.


Obtaining the geometry
- - - - - - - - - - -

The disk geometry parameters can be obtained by booting MS-DOS and running 
the program DPARAM.COM with the hexadecimal BIOS code of the drive as its 
argument, e.g. dparam 0x80 for the first hard disk. It displays the number 
of sectors per track, the number of heads per cylinder and the number of 
cylinders. All three numbers are one-based.

Alternatively, the geometry may also be determined by reading the 
information presented by the "setup" section of the ROM-BIOS or by using 
certain disk utilities under operating systems accessing the disk through 
the BIOS.


Specifying the geometry
- - - - - - - - - - - -

Disk geometry parameters are specified in the options section of the 
configuration file. Each disk parameter sub-section begins with 
DISK=<disk_device>, similar to the way how boot images are specified. It is 
suggested to group disk parameter sections together, preferably at the 
beginning or the end of the options section.

For each disk, the following variables can be specified: 

  BIOS=<bios_device_code>  Is the number the BIOS uses to refer to that 
    device. Normally, it's  0x80  for the first hard disk and  0x81  for 
    the second hard disk. Note that hexadecimal numbers have to begin with 
    "0x". If BIOS is omitted, LILO tries to "guess" that number. 
  SECTORS=<sectors>  and 
  HEADS=<heads>  specify the number of sectors per track and the number of 
    heads, i.e. the number of tracks per cylinder. Both parameters have to 
    be either specified together or they have to be entirely omitted. If 
    omitted, LILO tries to obtain that geometry information from the 
    kernel. 
  CYLINDERS=<cylinders>  Specifies the number of cylinders. This value is 
    only used for sanity checks. If CYLINDERS is omitted, LILO uses the 
    information obtained from the kernel if geometry information had to be 
    requested in order to determine some other parameter. Otherwise,* it 
    just assumes the number of cylinders to be 1024, which is the cylinder 
    limit imposed by the BIOS. 

  *  I.e. if the BIOS device code, the number of sectors, the number of 
    heads and the partition start are specified. Note that the number of 
    cylinders may appear to vary if CYLINDERS is absent and only some of 
    the partition starts are specified.

Additionally, partition sub-sub-sections can be added with 
PARTITION=<partition_device>. Each partition section can contain only one 
variable: 

  START=<partition_offset>  Specifies the zero-based number of the start 
    sector of that partition. The whole disk always has a partition offset 
    of zero. The partition offset is only necessary when using devices for 
    which the kernel does not provide that information, e.g. CD-ROMs. 

Example:

disk = /dev/sda
  bios = 0x80
  sectors = 32
  heads = 64
  cylinders = 632
  partition = /dev/sda1
    start = 2048
  partition = /dev/sda2
    start = 204800
  partition = /dev/sda3
    start = 500000
  partition = /dev/sda4
    start = 900000

Because many SCSI controllers don't support more than 1 GB when using the 
BIOS interface, LILO can't access files that are located beyond the 1 GB 
limit of large SCSI disks on such controllers and reports errors in these 
cases.


Disk parameter table
- - - - - - - - - -

The file /etc/disktab is the obsolete way to define the disk geometry. It 
is described here only for completeness. Its use with LILO 0.15 and newer 
is deprecated.

For each device (/dev/hda ->0x300, /dev/sda ->0x800, /dev/sda1 ->0x801, 
etc.), the BIOS code and the disk geometry have to be specified, e.g.

# /etc/disktab  -  LILO disk parameter table
#
# This table contains disk parameters for non-standard disks.
# Parameters in disktab _always_ override auto-detected disk parameters.
# Note: this file is typically not needed for normal use of LILO.

# Dev.  BIOS    Secs/   Heads/  Cylin-  Part.
# num.  code    track   cylin.  ders    offset
#                                      (optional)

0x800   0x80    32      64      631     0       # /dev/sda
0x801   0x80    32      64      631     32      # /dev/sda1
0x802   0x80    32      64      631     204800  # /dev/sda2

Those parameters are just a random example from my system. However, many 
SCSI controllers re-map the drives to 32 sectors and 64 heads. The number 
of cylinders does not have to be exact, but it shouldn't be lower than the 
number of effectively available cylinders.

Note that the device number and the BIOS code have to be specified as 
hexadecimal numbers with the "0x" prefix. Also note that the complete 
information has to be repeated for each partition.


Installation and updates
========================


Installation
------------

This section describes the installation of LILO. See section "LILO 
de-installation" for how to uninstall LILO.


Compatibility
- - - - - - -

The kernel header files have to be in /usr/include/linux and the kernel 
usually has to be configured by running  make config  before LILO can be 
compiled.

/bin/sh has to be a real Bourne shell. bash is sufficiently compatible, but 
some ksh clones may cause problems.

Using command-line options that are handled by init usually works with any 
current version of init. All currently available init packages typically 
support new features of LILO in the respective next release.

A file named INCOMPAT is included in the distribution. It describes 
incompatibilities to older versions of LILO and may also contain further 
compatibility notes.


Quick installation
- - - - - - - - -

If you want to install LILO on your hard disk and if you don't want to use 
all its features, you can use the quick installation script. Read QuickInst 
for details.

QuickInst can only be used for first-time installations or to entirely 
replace an existing installation, _not_ to update or modify an existing 
installation of LILO. Be sure you've extracted LILO into a directory that 
doesn't contain any files of other LILO installations.


Files
- - -

Some of the files contained in lilo.16.tar.gz:

  lilo/README   
     This documentation in plain ASCII format. Some sections containing 
    complex tables are only included in the LaTeX version in doc/user.tex 
  lilo/INCOMPAT   
     List of incompatibilities to previous versions of LILO. 
  lilo/CHANGES   
     Change history. 
  lilo/QuickInst   
     Quick installation script. 
  lilo/Makefile   
     Makefile to generate everything else. 
  lilo/*.c, lilo/*.h   
     LILO map installer C source. 
  lilo/*.S   
     LILO boot loader assembler source. 
  lilo/activate.c   
     C source of a simple boot partition setter. 
  lilo/dparam.s   
     Assembler source of a disk parameter dumper. 
  lilo/disktab   
     Sample disk parameter table. (Obsolete.) 
  lilo/mkdist   
     Shell script used to create the current LILO distribution. 
  lilo/doc/README   
     Description of how the documentation is generated. 
  lilo/doc/Makefile   
     Makefile used to convert the LaTeX source into either DVI output or 
    the plain ASCII README file. 
  lilo/doc/user.tex   
     LaTeX source of LILO's user's guide (this document). 
  lilo/doc/tech.tex   
     LaTeX source of LILO's technical overview. 
  lilo/doc/*.fig   
     Various xfig pictures used in the technical overview. 
  lilo/doc/fullpage.sty   
     Style file to save a few square miles of forest. 
  lilo/doc/rlatex   
     Shell script that invokes LaTeX repeatedly until all references have 
    settled. 
  lilo/doc/t2a.pl   
     Perl script to convert the LaTeX source of the user's guide to plain 
    ASCII. 

Files created after  make  in lilo/ (among others):

  lilo/any_b.b   
     Chain loader that swaps the first two floppy drives (i.e. "A:" and 
    "B:").  make install  puts this file into /boot 
  lilo/any_d.b   
     Chain loader that swaps the first two hard disk devices (i.e. "C:" and 
    "D:").  make install  puts this file into /boot 
  lilo/boot.b   
     Combined boot sector.  make install  puts this file into /boot 
  lilo/chain.b   
     Generic chain loader.  make install  puts this file into /boot 
  lilo/os2_d.b   
     Chain loader to load OS/2 from the second hard disk.  make install  
    puts this file into /boot 
  lilo/lilo   
     LILO (map) installer.  make install  puts this file into /sbin 
  lilo/activate   
     Simple boot partition setter. 
  lilo/dparam.com   
     MS-DOS executable of the disk parameter dumper. 


Normal first-time installation
- - - - - - - - - - - - - - -

First, you have to install the LILO files:

  - extract all files from lilo.<version>.tar.gz in a new directory.* 
  - configure the Makefile (see section "Build-time configuration") 
  - run  make  to compile and assemble all parts. 
  - run  make install  to copy all LILO files to the directories where 
    they're installed. /sbin should now contain the file lilo, /etc should 
    contain disktab** and /boot should contain the following files: 
    any_b.b, any_d.b, boot.b, chain.b and os2_d.b. 

  *  E.g. /usr/src/lilo

  **  Actually, it shouldn't, because disktab is now obsolete.

If you want to use LILO on a non-standard disk, you might have to determine 
the parameters of your disk(s) and specify them in the configuration file. 
See section "Disk geometry" for details. If you're using such a 
non-standard system, the next step is to test LILO with the boot sector on 
a floppy disk:

  - insert a blank (but low-level formatted) floppy disk into /dev/fd0. 
  - run  echo image=<kernel_image>  |
      /sbin/lilo -C - -b /dev/fd0 -v -v -v * 
  - reboot. LILO should now load its boot loaders from the floppy disk and 
    then continue loading the kernel from the hard disk. 

  *  If you've already installed LILO on your system, you might not want to 
    overwrite your old map file. Use the  -m  option to specify an 
    alternate map file name.

Now, you have to decide, which boot concept you want to use. Let's assume 
you have a Linux partition on /dev/hda2 and you want to install your LILO 
boot sector there. The DOS-MBR loads the LILO boot sector.

  - get a working boot disk, e.g. an install or recovery disk. Verify that 
    you can boot with this setup and that you can mount your Linux 
    partition(s) with it. 
  - if the boot sector you want to overwrite with LILO is of any value 
    (e.g. it's the MBR or if it contains a boot loader you might want to 
    use if you encounter problems with LILO), you should mount your boot 
    disk and make a backup copy of your boot sector to a file on that 
    floppy, e.g. dd if=/dev/hda of=/fd/boot_sector bs=512 count=1 
  - create the configuration file /etc/lilo.conf, e.g.
     <global settings>
       <image specifications>
       ...
     Be sure to use absolute paths for all files. Relative paths may cause 
    unexpected behaviour when using the  -r  option. 
  - now, you can check what LILO would do if you were about to install it 
    on your hard disk:
     /sbin/lilo -v -v -v -t 
  - if you need some additional boot utility (i.e. BOOTACTV), you should 
    install that now 
  - run /sbin/lilo to install LILO on your hard disk 
  - if you have to change the active partition, use fdisk or activate to do 
    that 
  - reboot 


Build-time configuration
------------------------

Certain build-time parameters can be configured. They can either be edited 
in the top-level Makefile or they can be stored in a file 
/etc/lilo.defines. Settings in the Makefile are ignored if that file 
exists.

The following items can be configured: 

   IGNORECASE   Makes image name matching case-insensitive, i.e. "linux" 
    and "Linux" are identical. This option is enabled by default. Note that 
    password matching is always case-sensitive. 
   NO1STDIAG   Do not generate diagnostics on read errors in the first 
    stage boot loader. This avoids possibly irritating error codes if the 
    disk controller has transient read problems. This option is disabled by 
    default. 
   NOINSTDEF   If the option INSTALL is omitted, don't install a new boot 
    sector, but try to modify the old boot sector instead. This option is 
    disabled by default. 
   ONE_SHOT   Disables the command-line timeout (configuration variable 
    TIMEOUT) if any key is pressed. This way, very short timeouts can be 
    used if PROMPT is set.  ONE_SHOT  is disabled by default. 
   READONLY   Disallows overwriting the default command line sector of the 
    map file. This way, command lines set with  -R  stay in effect until 
    they are explicitly removed. This option is disabled by default. 
   VARSETUP   Enables the use of variable-size setup segments. This option 
    is enabled by default and is only provided to fall back to fixed-size 
    setup segments in the unlikely case of problems when using old kernels. 

/etc/lilo.defines should be used if one wishes to make permanent 
configuration changes. The usual installation procedures don't touch that 
file. Example:

-DIGNORECASE -DONE_SHOT


Updates
-------

LILO is affected by updates of kernels, the whole system and (trivially) of 
LILO itself. Typically, only /sbin/lilo has to be run after any of those 
updates and everything will be well again (at least as far as LILO is 
concerned).


LILO update
- - - - - -

When updating to a new version of LILO, the initial steps are the same as 
for a first time installation: extract all files, configure the Makefile, 
run  make  to build the executables and run  make install  to install the 
files.

The old versions of boot.b, chain.b, etc. are automatically renamed to 
boot.old, chain.old, etc. This is done to ensure that you can boot even if 
the installation procedure does not finish. boot.old, chain.old, etc. can 
be deleted after the map file is rebuilt.

Because the locations of boot.b, chain.b, etc. have changed and because the 
map file format may be different too, you have to update the boot sector 
and the map file. Run /sbin/lilo to do this.


Kernel update
- - - - - - -

Whenever any of the kernel files that are accessed by LILO is moved or 
overwritten, the map has to be re-built.* Run /sbin/lilo to do this.

  *  It is advisable to keep a second, stable, kernel image that can be 
    booted if you forget to update the map after a change to your usual 
    kernel image.

The kernel has a make target "zlilo" that copies the kernel to /vmlinuz and 
runs /sbin/lilo.


System upgrade
- - - - - - -

Normally, system upgrades (i.e. installation or removal of packages, 
possibly replacement of large a part of the installed binaries) do not 
affect LILO. Of course, if a new kernel is installed in the process, the 
normal kernel update procedure has to be followed (see section "Kernel 
update"). Also, if kernels are removed or added, it may be necessary to 
update the configuration file.

If LILO is updated by this system upgrade, /sbin/lilo should be run before 
booting the upgraded system. It is generally a good idea not to rely on the 
upgrade procedure to perform this essential step automatically.

However, system upgrades which involve removal and re-creation of entire 
partitions (e.g. /, /usr, etc.) are different. First, they should be 
avoided, because they bear a high risk of losing other critical files, e.g. 
the /etc/Xconfig you've spent the last week fiddling with. If an upgrade 
really has to be performed in such a brute-force way, this is equal with 
total removal of LILO, followed by a new installation. Therefore, the 
procedures described in the sections "LILO de-installation" and "LILO 
update" have to be performed. If you've forgotten to make a backup copy of 
/etc/lilo.conf (and possibly also of /etc/disktab) before the destructive 
upgrade, you might also have to go through section "Normal first-time 
installation" again.


LILO de-installation
--------------------

In order to stop LILO from being invoked when the system boots, its boot 
sector has to be either removed or disabled. All other files belonging to 
LILO can be deleted _after_ removing the boot sector, if desired.*

  *  Backup copies of old boot sectors may be needed when removing the boot 
    sector. They are stored in /boot.

Again, _when removing Linux, LILO must be de-installed before (!) its files 
(/boot, etc.) are deleted._ This is especially important if LILO is 
operating as the MBR.

LILO 0.14 (and newer) can be de-installed with lilo -u. If LILO 0.14 or 
newer is currently installed, but the first version of LILO installed was 
older than 0.14, lilo -U may work. When using -U, the warning at the end of 
this section applies.

If LILO's boot sector has been installed on a primary partition and is 
booted by the "standard" MBR or some partition switcher program, it can be 
disabled by making a different partition active. MS-DOS' FDISK, Linux fdisk 
or LILO's activate can do that.

If LILO's boot sector is the master boot record (MBR) of a disk, it has to 
be replaced with a different MBR, typically MS-DOS' "standard" MBR. When 
using MS-DOS 5.0 or above, the MS-DOS MBR can be restored with FDISK /MBR. 
This only alters the boot loader code, not the partition table.

LILO automatically makes backup copies when it overwrites boot sectors. 
They are named /boot/boot.<nnnn>, with <nnnn> corresponding to the device 
number, e.g.  0300  is /dev/hda,  0800  is /dev/sda, etc. Those backups can 
be used to restore the old MBR if no easier method is available. The 
commands are
  dd if=/boot/boot.0300 of=/dev/hda bs=446 count=1  or
  dd if=/boot/boot.0800 of=/dev/sda bs=446 count=1 
 respectively.

_WARNING:_ Some Linux distributions install boot.<nnnn> files from the 
system where the distribution was created. Using those files may yield 
unpredictable results. Therefore, the file creation date should be 
carefully checked.


Installation of other operating systems
---------------------------------------

Some other operating systems (e.g. MS-DOS 6.0) appear to modify the MBR in 
their install procedures. It is therefore possible that LILO will stop to 
work after such an installation and Linux has to be booted from floppy 
disk. The original state can be restored by either re-running /sbin/lilo 
(if LILO is installed as the MBR) or by making LILO's partition active (if 
it's installed on a primary partition).

It is generally a good idea to install LILO after the other operating 
systems have been installed. E.g. OS/2 is said to cause trouble when 
attempting to add it to an existing Linux system. (However, booting from 
floppy and running /sbin/lilo should get around most interferences.)

Typically, the new operating system then has to be added to LILO's 
configuration (and /sbin/lilo has to be re-run) in order to boot it.

See also section "Other problems" for a list of known problems with some 
other operating systems.


Troubleshooting
===============

All parts of LILO display some messages that can be used to diagnose 
problems.


Map installer warnings and errors
---------------------------------

Most messages of the map installer (/sbin/lilo) should be self-explanatory. 
Some messages that indicate common errors are listed below. They are 
grouped into fatal errors and warnings (non-fatal errors).


Fatal errors
- - - - - - 

   Boot sector of <device_name> doesn't have a boot signature   
   Boot sector of <device_name> doesn't have a LILO signature    
     The sector from which LILO should be uninstalled doesn't appear to be 
    a LILO boot sector. 
   Can't put the boot sector on logical partition <number>    
     An attempt has been made to put LILO's boot sector on the current root 
    file system partition which is on a logical partition. This usually 
    doesn't have the desired effect, because common MBRs can only boot 
    primary partitions. This check can be bypassed by explicitly specifying 
    the boot partition with the  -b  option or by setting the configuration 
    variable BOOT. 
   Checksum error    
     The descriptor table of the map file has an invalid checksum. Refresh 
    the map file _immediately_ ! 
   Device 0x<number>: Got bad geometry <sec>/<hd>/<cyl>    
     The device driver for your SCSI controller does not support geometry 
    detection. You have to specify the geometry explicitly (see section 
    "Disk geometry"). 
   Device 0x<number>: Invalid partition table, entry <number>    
     The 3D and linear addresses of the first sector of the specified 
    partition don't correspond. This is typically caused by partitioning a 
    disk with a program that doesn't align partitions to tracks and later 
    using PC/MS-DOS or OS/2 on that disk. LILO can attempt to correct the 
    problem, see "General per-image options". 
   <device_name> is not a valid partition device    
     The specified device is either not a device at all, a whole disk, or a 
    partition on a different disk than the one in whose section its entry 
    appears. 
   <device_name> is not a whole disk device    
     Only the geometry of whole disks (e.g. /dev/hda, /dev/sdb, etc.) can 
    be redefined when using DISK sections.* 
   DISKTAB and DISK are mutually exclusive    
     You cannot use a disktab file and disk geometry definitions in the 
    configuration file at the same time. Maybe /etc/disktab was 
    accidentally used, because that's the default for 
    backward-compatibility. You should delete /etc/disktab after completing 
    the transition to DISK sections. 
   Duplicate entry in partition table    
     A partition table entry appears twice. The partition table has to be 
    fixed with fdisk. 
   Duplicate geometry definition for <device_name>    
     A disk or partition geometry definition entry for the same device 
    appears twice in the configuration file. Note that you mustn't write a 
    partition section for the whole disk - its start sector is always the 
    first sector of the disk. 
   First sector of <device> doesn't have a valid boot signature    
     The first sector of the specified device does not appear to be a valid 
    boot sector. You might have confused the device name.** 
   geo_comp_addr: Cylinder <number> beyond end of media (<number>)    
     A file block appears to be located beyond the last cylinder of the 
    disk. This probably indicates an error in the disk geometry 
    specification (see sections "Disk geometry" and "Disk parameter table") 
    or a file system corruption. 
   geo_comp_addr: Cylinder number is too big (<number> > 1023)    
     Blocks of a file are located beyond the 1024th cylinder of a hard 
    disk. LILO can't access such files, because the BIOS limits cylinder 
    numbers to the range 0...1023. Try moving the file to a different 
    place, preferably a partition that is entirely within the first 1024 
    cylinders of the disk. 
   Hole found in map file (<location>)    
     The map installer is confused about the disk organization. Please 
    report this error. 
   <item> doesn't have a valid LILO signature    
     The specified item has been located, but is not part of LILO. 
   <item> has an invalid stage code (<number>)    
     The specified item has probably been corrupted. Try re-building LILO. 
   <item> is version <number>. Expecting version <number>.    
     The specified entity is either too old or too new. Make sure all parts 
    of LILO (map installer, boot loaders and chain loaders) are from the 
    same distribution. *** 
   Kernel <name> is too big    
     The kernel image (without the setup code) is bigger than 512 kbytes. 
    LILO would overwrite itself when trying to load such a kernel. Try 
    removing some unused drivers and compiling the kernel again. With 
    recent (compressed) kernels, the reason for this error is most likely 
    that the kernel image is damaged or that it contains trailing "junk", 
    e.g. as the result of copying an entire boot floppy to the hard disk. 
   Map <path> is not a regular file.    
     This is probably the result of an attempt to omit writing a map file, 
    e.g. with  -m /dev/null . The  -t  option should be used to accomplish 
    this. 
   Must specify LOADER for BIOS device <number>    
     When booting an operating system from any device than the first hard 
    or floppy disk, specifying the chain loader (option LOADER in the image 
    section) is now mandatory. 
   Must specify SECTORS and HEADS together    
     It is assumed that disks with a "strange" number of sectors will also 
    have a "strange" number of heads. Therefore, it's all or nothing. 
   Partition entry not found    
     The partition from which an other operating system should be booted 
    isn't listed in the specified partition table. This either means that 
    an incorrect partition table has been specified or that you're trying 
    to boot from a logical partition. The latter usually doesn't work. You 
    can bypass this check by omitting the partition table specification 
    (e.g. omitting the variable TABLE). 
   Sorry, don't know how to handle device <number>    
     LILO uses files that are located on a device for which there is no 
    easy way to determine the disk geometry. Such devices have to be 
    explicitly described, see section "Disk geometry". 
   Timestamp in boot sector of <device> differs from date of <file>    
     The backup copy of the boot sector does not appear to be an ancestor 
    of the current boot sector. If you are absolutely sure that the boot 
    sector is indeed correct, you can bypass this check by using  -U  
    instead of  -u . 
   Trying to map files from your RAM disk. Please check -r option or ROOT 
  environment variable.    
     Most likely, you or some installation script is trying to invoke LILO 
    in a way that some of the files is has to access reside on the RAM 
    disk. Normally, the  ROOT  environment variable should be set to the 
    mount point of the effective root device if installing LILO with a 
    different root directory. See also sections "Create or update map" and 
    "Normal first-time installation". 
   write <item>: <error_reason>    
     The disk is probably full or mounted read-only. 

  *  When using a disktab file, you don't have this restriction. The 
    additional flexibility offered by this is, however, useless and 
    dangerous.

  **  Because different partition programs may display the partitions in a 
    different order, it is possible that what you think is your first 
    partition isn't /dev/hda1, etc. A good method to verify the content of 
    a partition is to try to mount it.

  ***  The expected version number may be different from the version number 
    of the LILO package, because file version numbers are only increased 
    when the file formats change.


Warnings
- - - -

Warnings labeled with "Warning" can be turned off with the NOWARN option.

   FIGETBSZ <file_name>: < error_reason>    
     The map installer is unable to determine the block size of a file 
    system. It assumes a block size of two sectors (1kB). 
   Ignoring entry '<variable_name>'    
     The command-line option corresponding to the specified variable is 
    set. Therefore, the configuration file entry is ignored. 
   Setting DELAY to 20 (2 seconds)    
     Because accidentally booting the wrong kernel or operating system may 
    be very inconvenient on systems that are not run from a local display, 
    the minimum delay is two seconds if the SERIAL variable is set. 
   (temp) <item>: <error_reason>    
     Deleting a temporary file has failed for the specified reason. 
   Warning: BIOS drive 0x<number> may not be accessible    
     Because most BIOS versions only support two floppies and two hard 
    disks, files located on additional disks may be inaccessible. This 
    warning indicates that some kernels or even the whole system may be 
    unbootable. 
   Warning: <config_file> should be owned by root    
     In order to prevent users from compromising system integrity, the 
    configuration file should be owned by root and write access for all 
    other users should be disabled. 
   Warning: <config_file> should be readable only for root if using 
  PASSWORD    
     Users should not be allowed to read the configuration file when using 
    the PASSWORD option, because then, it contains unencrypted passwords. 
   Warning: <config_file> should be writable only for root    
     See " Warning: <config_file> should be owned by root ". 
   Warning: device 0x<number> exceeds 1024 cylinder limit    
     A disk or partition exceeds the 1024 cylinder limit imposed by the 
    BIOS. This may result in a fatal error in the current installation run 
    or in later installation runs. See " geo_comp_addr: Cylinder number is 
    too big (<number> > 1023) " for details. 
   Warning: <device> is not on the first disk    
     The specified partition is probably not on the first disk. LILO's boot 
    sector can only be booted from the first disk unless some special boot 
    manager is used. 
   WARNING: The system is unbootable !    
     One of the last installation steps has failed. This warning is 
    typically followed by a fatal error describing the problem. 


LILO start message
------------------

When LILO loads itself, it displays the word "LILO". Each letter is printed 
before or after performing some specific action. If LILO fails at some 
point, the letters printed so far can be used to identify the problem. This 
is described in more detail in the technical overview.

Note that some hex digits may be inserted after the first "L" if a 
transient disk problem occurs. Unless LILO stops at that point, generating 
an endless stream of error codes, such hex digits do not indicate a severe 
problem.

  (<nothing>)  No part of LILO has been loaded. LILO either isn't installed 
    or the partition on which its boot sector is located isn't active. 
   L<error>...   The first stage boot loader has been loaded and started, 
    but it can't load the second stage boot loader. The two-digit error 
    codes indicate the type of problem. (See also section "Disk error 
    codes".) This condition usually indicates a media failure or a geometry 
    mismatch (e.g. bad disk parameters, see section "Disk geometry"). 
   LI   The first stage boot loader was able to load the second stage boot 
    loader, but has failed to execute it. This can either be caused by a 
    geometry mismatch or by moving /boot/boot.b without running the map 
    installer. 
   LIL   The second stage boot loader has been started, but it can't load 
    the descriptor table from the map file. This is typically caused by a 
    media failure or by a geometry mismatch. 
   LIL?   The second stage boot loader has been loaded at an incorrect 
    address. This is typically caused by a subtle geometry mismatch or by 
    moving /boot/boot.b without running the map installer. 
   LIL-   The descriptor table is corrupt. This can either be caused by a 
    geometry mismatch or by moving /boot/map without running the map 
    installer. 
   LILO   All parts of LILO have been successfully loaded. 


Disk error codes
----------------

If the BIOS signals an error when LILO is trying to load a boot image, the 
respective error code is displayed. The following BIOS error codes are 
known:

   0x00   "Internal error". This code is generated by the sector read 
    routine of the LILO boot loader whenever an internal inconsistency is 
    detected. This might be caused by corrupt files. Try re-building the 
    map file. 
   0x01   "Illegal command". This shouldn't happen, but if it does, it may 
    indicate an attempt to access a disk which is not supported by the 
    BIOS. See also "Warning: BIOS drive 0x<number> may not be accessible" 
    in section "Warnings". 
   0x02   "Address mark not found". This usually indicates a media problem. 
    Try again several times. 
   0x03   "Write-protected disk". This shouldn't happen. 
   0x04   "Sector not found". This typically indicates a geometry mismatch. 
    If you're booting a raw-written disk image, verify whether it was 
    created for disks with the same geometry as the one you're using. If 
    you're booting from a SCSI disk or a large IDE disk, you should check, 
    whether LILO has obtained correct geometry data from the kernel or 
    whether the geometry definition corresponds to the real disk geometry. 
    (See section "Disk geometry".) Removing COMPACT may help too. So may 
    adding LINEAR. 
   0x06   "Change line active". This should be a transient error. Try 
    booting a second time. 
   0x08   "DMA overrun". This shouldn't happen. Try booting again. 
   0x09   "DMA attempt across 64k boundary". This shouldn't happen. Try 
    omitting the COMPACT option and report this problem to the author. 
   0x0C   "Invalid media". This shouldn't happen and might be caused by a 
    media error. Try booting again. 
   0x10   "CRC error". A media error has been detected. Try booting several 
    times, running the map installer a second time (to put the map file at 
    some other physical location or to write "good data" over the bad 
    spot), mapping out the bad sectors/tracks and, if all else fails, 
    replacing the media. 
   0x20   "Controller error". This shouldn't happen. 
   0x40   "Seek failure". This might be a media problem. Try booting again. 
   0x80   "Disk timeout". The disk or the drive isn't ready. Either the 
    media is bad or the disk isn't spinning. If you're booting from a 
    floppy, you might not have closed the drive door. Otherwise, trying to 
    boot again might help. 

Generally, invalid geometry and attempts to use more than two disks without 
a very modern BIOS may yield misleading error codes. Please check carefully 
if /sbin/lilo doesn't emit any warnings. Then try using the LINEAR option 
(see section "Global options").


Other problems
--------------

This section contains a collection of less common problems that have been 
observed. See also section "Installation of other operating systems" for 
general remarks on using LILO with other operating systems. Some of the 
problems are obscure and so are the work-arounds.

  - If LILO doesn't go away even if you erase its files, format your Linux 
    partition, etc., you've probably installed LILO as your MBR and you've 
    forgotten to deinstall it before deleting its files. See section "LILO 
    de-installation" for what you can do now. 
  - For yet unknown reasons, LILO may fail on some systems with AMI BIOS if 
    the "Hard Disk Type 47 RAM area" is set to "0:300" instead of "DOS 1K". 
  - Some disk controller BIOSes perform disk geometry/address translations 
    that are incompatible with the way the device's geometry is seen from 
    Linux, i.e. without going through the BIOS. Particularly, large IDE 
    disks and some recent PCI SCSI controllers appear to have this problem. 
    In such cases, either the translated geometry has to be specified in a 
    DISK section or the sector address translation can be deferred by using 
    the LINEAR option. In a setup where floppies are not normally used for 
    booting, the LINEAR approach should be preferred, because this avoids 
    the risk of specifying incorrect numbers. 
  - OS/2 is said to be bootable from a logical partition with LILO acting 
    as the primary boot selector if LILO is installed on the MBR, the OS/2 
    BootManager is on an active primary partition and LILO boots 
    BootManager. Putting LILO on an extended partition instead is said to 
    crash the OS/2 FDISK in this scenario.

     Note that booting LILO from BootManager (so BootManager is the primary 
    selector) or booting OS/2 directly from a primary partition (without 
    BootManager) should generally work. See also section "Installation of 
    other operating systems". 
  - Windows NT is reported to be bootable with LILO when LILO acts as the 
    MBR and the Windows NT boot loader is on the DOS partition. However, 
    NT's disk manager complains about LILO's MBR when trying to edit the 
    partition table. 
  - Some PC UNIX systems (SCO and Unixware have been reported to exhibit 
    this problem) depend on their partition being active. Such a setup can 
    currently only be obtained by installing LILO as the MBR and making the 
    respective partition active.* 
  - Future Domain TMC-1680 adapters with the BIOS versions 3.4 and 3.5 
    assign BIOS device numbers in the wrong order, e.g. on a two-disk 
    system, /dev/sda becomes  0x81  and /dev/sdb becomes  0x80 . This can 
    be fixed with the following disk section:
     disk=/dev/sda bios=0x81 disk=/dev/sdb bios=0x80
     Note that this is only valid for a two-disk system. In three-disk 
    systems, /dev/sdc would become  0x80 , etc. Also, single-disk systems 
    don't have this problem (and the "fix" would break them). 

  *  Future versions of LILO may be able to change the active flag 
    dynamically.
