发信人: netiscpu (说不如做), 信区: Linux
标 题: [B] Red Hat Linux Unleashed (4)
发信站: 紫 丁 香 (Sat Jul 25 03:08:43 1998), 转信
LILO
_________________________________________________________________
o Using LILO to Boot Off the Hard Drive
# LILO Command-Line Arguments
# Configuration Parameters
# The boot Prompt
# Uninstalling LILO
# Map Installer Errors
# LILO Error Codes
o Using BOOTLIN Instead of LILO
o Restoring the MBR
o Summary
_________________________________________________________________
4
LILO
Whenever you hear about Linux, you'll also hear about LILO. LILO is
the boot loader used by Linux to load the operating system kernel.
Whenever the Linux kernel is changed or moved, LILO must be invoked to
rebuild a map of the kernel locations. LILO is versatile; it can boot
Linux kernels from any type of file system, including floppy disk, as
well as from other operating systems.
This chapter looks at LILO, the way hard disks are laid out with
Linux, the boot process, and the most common boot processes and LILO's
interactions with each. This should help you install and use LILO
efficiently and effectively.
Using LILO to Boot Off the Hard Drive
LILO (which means LInux LOader) is a bit tricky to use if you are not
familiar with it and its purpose. You need to install the LILO
program, which changes the boot sector of your hard drive to allow you
to choose between a DOS or a Linux partition as the boot source
partition. LILO is included with Red Hat Linux and is installed
automaically when you load the system from CD-ROM.
Some of the features of LILO include the following:
* It is independent of the file system. You can use LILO with DOS,
UNIX, OS/2, and Windows NT.
* It can replace the master boot record on your hard drive.
* It can use up to 16 different boot images on several partitions on
your hard drive. Each image can be protected by a password.
* It provides support for boot-sector, map-file, and boot images to
reside on different disks or partitions.
Using LILO may seem risky at first; it can ruin your hard drive or
leave you with a system that you cannot boot. To prepare yourself for
this mishap, keep a boot disk handy. Also, you have to do this
installation as root, so be careful.
If you have already installed Red Hat Linux, the LILO files will exist
on your hard drive. If you are about to install Red Hat Linux, the
LILO installation routine will be activated automatically as part of
the installation process. If you want to redo the LILO system at any
time, though, you can run the program /sbin/liloconfig.
The liloconfig program is easy to use and asks several questions about
your system. The sheer number of possibilities cannot be completely
covered here, but here are the terms with which you must be familiar:
* /dev/hda and /dev/hdb refer to both IDE hard drives 1 and 2 on
your system. Individual partitions on each hard drive are referred
to as /dev/hda1, /dev/hda2, /dev/hda3, and so on for drive 1.
Similar to this are the partitions for drive 2: /dev/dhb1 and so
on.
* SCSI hard drives are referred to as /dev/sda and /dev/sdb for
drive 1 and 2, respectively.
* The Master Boot Record (MBR) is the first boot sector of your
drive that contains the partitioning information and boot-strap
code. LILO will change this sector and make it incompatible with
DOS. The DOS MBR program simply loads MS-DOS from the boot sector,
which in turns loads command.com.
The liloconfig program asks you where you want to install LILO. If you
are running multiple operating systems and plan to switch between them
often, try installing on the Linux partition superblock. If you will
use Linux primarily or only, install on the Master Boot Record. You
will then be asked about the ability to load other operating systems
from the boot prompt, and you get to identify each operating system
and provide a name for it. This lets you start DOS, for example, from
the boot prompt by entering the name you assigned to DOS partition.
After the liloconfig program has run, it will create a file called
lilo.conf for you in the /etc directory. If you already have this file
in your /etc directory, you can edit it manually using any ASCII
editor. Of course, depending on how your system is set up, the
contents of your Linux installation may vary. A sample lilo.conf file
for a system containing both DOS and Linux looks like this:
boot=/dev/hda
map=/boot/map
install=/boot/boot.b
prompt
timeout=50
image=/vmlinuz
root=/dev/hda2
label=linux
other=/dev/hda1
label=dos
table=/dev/hda
In this lilo.conf file, you can see two different kernels that can be
booted from /dev/hda. The first image is the default image, called
vmlinuz. The other image is labeled DOS for the DOS partition. Typing
dos at the boot prompt will boot this partition.
LILO Command-Line Arguments
The LILO configuration is written to disk using the /sbin/lilo
command. The /sbin/lilo installer accepts several command-line
options. A few of the more usual ones are listed here.
* -C <config_file>. Specifies the configuration file that is used by
the map installer. If -C is omitted, /etc/lilo/config is used. In
this example, you would use /etc/lilo.conf.
* -q. Lists the currently mapped files.
* -r <root_directory>. Changes the directory 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, for example, when recovering from an installation
failure with an install disk.
* -t. Test only. Performs the entire installation procedure without
replacing the map file or writing the modified boot sector. This
can be used in conjunction with the -v option to verify that LILO
will use sane values.
* -v. Be verbose about what it's doing. If you don't do this, the
installation process will not display any messages or status
information.
* -u [ device_name ]. Restores the backup copy of the specified boot
sector. The name is normally derived from its present name.
* -V. Prints the version number and exits.
Configuration Parameters
The /etc/lilo.conf file can have the following parameters. All of
these can be set from the command line, but storing them in a
configuration file is more reliable. The following options are
available to you:
* boot=<boot_device>. Sets the name of the device 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.
* linear. Generates 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,
where linear is used, may not be portable.
* install=<boot_sector>. Installs the specified file as the new boot
sector. If install is omitted, /etc/lilo/boot.b is used as the
default.
* disktab=<disktab_file>. Specifies the name of the disk parameter
table. The map installer looks for /etc/lilo/disktab if disktab is
omitted.
* map=<map_file>. Specifies the location of the map file. If map is
omitted, the file /etc/lilo/map is used.
* message=<message_file>. Specifies a file containing a message that
is displayed before the boot prompt. No message is displayed when
waiting for a Shift key after printing "LILO." The FF character
([Ctrl L]) clears the local screen. The size of the message file
is limited to 65,535 bytes. The map file has to be rebuilt if the
message file is changed or moved. The default file for messages is
the /etc/boot.message file. Use this file to display boot options
for your LILO configuration.
* verbose=<level>. Turns on lots of progress reporting. Higher
numbers give more verbose output.
* backup=<backup_file>. Copies the original boot sector to
<backup_file> (which may also be a device, such as /dev/null)
instead of to /etc/lilo/boot.<number>.
* force-backup=<backup_file>. Like backup, but overwrites an old
backup copy if it exists. backup=<backup_file> is ignored if
force-backup appears in the same configuration file.
* prompt. Forces entering the boot prompt without expecting any
prior key presses. Unattended reboots are impossible if prompt is
set and timeout isn't.
* timeout=<tsecs>. Sets a time out (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.
* serial=<parameters>. Enables control from a serial line. The
specified serial port must be initialized, and LILO is accepting
input from it and from the PC's keyboard. Sending a break on the
serial line corresponds to pressing the 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—that is, if the line is connected to a modem.
The parameter string has the 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
as well. Additionally, the comma has to be omitted only if the
port number is specified.
<port>. The number of the serial port, zero-based. 0 corresponds
to COM1.
alias /dev/ttyS0, alias /dev/ttys1, alias /dev/ttys2, alias
/dev/ttys3. 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 eighth bit. The following (upper- or
lowercase) 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.
* ignore-table. Tells LILO to ignore corrupt partition tables.
* fix-table. Allows LILO to adjust 3-D addresses in partition
tables. Each partition entry contains a 3-D (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 (such as PC/MS-DOS or OS/2) are using the
same disk, the operating system may change the 3-D address. LILO
can store its boot sector only on partitions where both address
types correspond. LILO readjusts incorrect 3-D start addresses if
fix-table is set.
______________________________________________________________
NOTE: fix-table does not guarantee that other operating systems
might not attempt to reset the address later. It is also possible
that this change has other, unexpected side effects. The correct
fix is to repartition the drive with a program that does align
partitions to tracks.
______________________________________________________________
* password=<password>. Sets a password for all images.
* unsafe. This keyword is placed after a definition for a partition.
The keyword tells LILO not to attempt to read the MBR or that
disk's partition table entry. You can declare all the partitions
in your system as a log of all exisiting partitions, then place
the unsafe keyword entry to prevent LILO from reading it.
The kernel configuration parameters append, ramdisk, read-only,
read-write, root, and vga can be set in the options section. They are
used as defaults if they aren't specified in the configuration
sections of the respective kernel images.
If the option -q is specified on the command line, the currently
mapped files are listed. Otherwise, a new map is created for the
images described in the configuration file /etc/lilo/config and they
are written to in the boot sector.
The boot Prompt
When the system boots up, after the keyboard test, press and hold down
one of any one of these keys: Alt, Shift, or Ctrl (or you can set the
Caps Lock or Scroll Lock key). If any of these keys are pressed, LILO
displays the boot: prompt and waits for the name of a boot image.
Pressing the Tab key or typing ? gives you a list of names recognized
by LILO. If you do not press any of these keys, LILO will boot up the
first it finds in the lilo.conf file kernel (in this case, vmlinuz.cd)
if there is no timeout specified in the /etc/lilo.conf file.
LILO can also pass command-line options to the kernel. Command-line
options are words that follow the name of the boot image and are
separated by spaces. Currently, the kernel recognizes the options
root=<device>, ro, and rw, and all current init programs also
recognize the option single, which boots the system in single-user
mode. This bypasses all system-initialization procedures and directly
starts a root shell on the console. Multiuser mode can be entered by
exiting the single-user shell or by rebooting.
The option vga is processed by the boot loader itself. The option
vga=<mode> alters the VGA mode that was set at startup. The legal
values for mode are NORMAL, EXTENDED, ASK, or a decimal number for the
BIOS mode command. You can get a list of available modes by typing
vga=ask and pressing Enter.
The root=<device> option 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 a hexadecimal device number or the full
pathname of the device, such as /dev/hda3. (The device names
are hard-coded in the kernel.)
ro instructs the kernel to mount the root file system as
read-only. rw mounts it as read-write. If neither ro nor rw
is specified, the setting from the boot image is used.
The no387 option disables using the hardware FPU.
Depending on the kernel configuration, some special configuration
options for nonstandard hardware might be recognized as well. Some of
these boot prompts include the following :
* For a Panasonic CD-ROM with SoundBlaster support, use
sbpcd=0x340,SoundBlaster.
* For a bus mouse, use bmouse=irq.
* For reserving ports from being autoprobed by device drivers in
special hardware device-conflict situations, you can use
reserve=port,size. For example, reserve=0x200,8 will reserve 8
ports starting at 0x200 from being probed by device drivers.
* Ethernet cards usually take parameter from the ether=x,x,x,...
command. The actual parameters sent depend on the type of card.
* For Mitsumi CD-ROM, use mcd=port,irq—for example,
mcd=0x340,11.
* If your Ethernet card is not recognized, try ether=10,0x340 to
probe for it at port 0x340 using interrupt 10. Note that the
interrupt number here is given before the port number is given for
the Mitsumi CD-ROM driver.
The parameters for each type of device will come with their
documentation, so do not assume anything. Use only specified values.
If you do follow instructions, you may wind up causing irrecoverable
errors, which may lead to a corrupt file system.
Uninstalling LILO
In order to keep 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.
LILO 0.14 (and newer) can be uninstalled with the lilo -u command.
If LILO's boot sector has been installed on a primary partition and is
booted by the standard MBR or some partition-switching program, it can
be disabled by making a different partition active. MS-DOS's FDISK,
Linux's 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's standard
MBR. When using MS-DOS 5.0 or above, the MS-DOS MBR can be restored
with FDISK /MBR. This alters only the boot loader code, not the
partition table. LILO automatically makes backup copies when it
overwrites boot sectors. They are named /etc/lilo/boot.<nnnn>, with
<nnnn> corresponding to the device number—that is, 0300 is
/dev/hda, 0800 is /dev/sda, and so on. Those backups can be used to
restore the old MBR if no easier method is available.
The commands are
dd if=/etc/lilo/boot.0300 of=/dev/hda bs=446 count=1
or
dd if=/etc/lilo/boot.0800 of=/dev/sda bs=446 count=1
respectively.
______________________________________________________________
NOTE: Some other operating systems (such as MS-DOS 6.0) appear to
modify the MBR in their install procedures. It is therefore
possible that LILO will cease to work after such an installation
and Linux has to be booted from floppy disk. The original state can
be restored by either rerunning /etc/lilo/lilo (if LILO is
installed as the MBR) or by making LILO's partition active (if it's
installed on a primary partition).
Typically, the new operating system then has to be added to LILO's
configuration (and /etc/lilo/lilo has to be rerun) in order to boot
it.
______________________________________________________________
Map Installer Errors
Some messages that indicate common errors when installing the maps are
as follows:
* Can't put the boot sector on logical partition <number>
You attempted 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 boot only
primary partitions. This check can be bypassed by explicitly
specifying the boot partition with the -b option or by setting the
configuration variable boot.
* Device 0x<number>: Got bad geometry <sec>//<cyl>
The device driver for your SCSI controller does not support
geometry detection. You have to use an /etc/lilo/disktab file.
* Device 0x<number>: Invalid partition table, entry <number>
The 3-D and linear addresses of the first sector of the specified
partition don't correspond. LILO can attempt to correct the
problem; see variable FIX-TABLE.
* 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. Check the device name.
* geo_comp_addr: Cylinder number is too big (<number> > 1023)
A file is 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.
* <item> doesn't have a valid LILO signature
The specified item has been located, but it is not part of LILO.
If <item> is the first boot sector, you've probably forgotten to
specify the -i option or the install variable to install the LILO
boot sector.
* <item> has an invalid stage code (<number>)
The specified item has probably been corrupted. Rebuild 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 512KB.
LILO would overwrite itself when trying to load such a kernel. Try
removing some unused drivers and compiling the kernel again.
* Partition entry not found
The partition from which another operating system should be booted
isn't listed in the specified partition table. This means either
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 (that is, 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
described in the file /etc/lilo/disktab.
LILO Error Codes
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. The following is the list of error messages
you can see:
(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. (They are described
in the next section.) This condition usually indicates a
media failure or a geometry mismatch (that is, bad parameters
in /etc/lilo/disktab).
LI The first-stage boot loader was able to load the second-stage
boot loader but has failed to execute it. This can be caused
either by a geometry mismatch or by moving /etc/lilo/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 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 /etc/lilo/boot.b without running the
map installer.
LIL- The descriptor table is corrupt. This can be caused either
by a geometry mismatch or by moving /etc/lilo/map without
running the map installer.
LILO All parts of LILO have been successfully loaded.
There are also BIOS error codes that you might get while loading LILO.
These are listed in Table 4.1.
Table 4.1. BIOS error codes.
Code Value
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 rebuilding the
map file.
0x01 Illegal command. This shouldn't happen.
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, you should check whether LILO has
obtained correct geometry data from the kernel or whether the contents
of your /etc/lilo/disktab file correspond to the real disk geometry.
Removing compact may help too.
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 64KB boundary. This shouldn't happen. Try
omitting the -c option.
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.
Using BOOTLIN Instead of LILO
The BOOTLIN package uses the DOS MBR to boot off the hard drive. To
install this package, you must take the following steps:
1. From within Linux, copy a bootable kernel to your DOS partition.
2. Edit config.sys on the DOS partition to include two files:
BOOT.SYS and BOOTLIN.SYS. The README files for these packages tell
you how.
3. Reboot.
Now when you reboot, the BOOT.SYS and BOOTLIN.SYS files will boot into
Linux for you.
To get back to running only DOS, remove the BOOTLIN.SYS and BOOT.SYS
from your config.sys file.
The disadvantage of this approach is that you are limited to having
DOS on your hard drive.
Restoring the MBR
If you want to restore the MBR to the original DOS MBR, you can use
the following procedure:
1. Boot from a DOS floppy.
2. Run fdisk /MBR from the DOS prompt. (You can also use the command
SYS C:.)
3. Reboot.
Summary
This chapter covered the topic of installing, configuring, and using
LILO. It also covered some of the basic errors you can face and how to
set up LILO using the liloconfig utility. The information you have
learned from this topic should get you started in setting up LILO to
boot Linux on your machine off the hard drive.
--
Enjoy Linux!
-----It's FREE!-----
※ 修改:．netiscpu 于 Jul 25 03:42:44 修改本文．[FROM: mtlab.hit.edu.cn]
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