Linux Cubed Series 7: Sunsite/Linux Cubed Series 7 - Sunsite Vol 1.iso/system/admin/linuxcon.6/linuxcon/usr/lib/linuxconf/help.eng/askrunlevel/lilo.help

Text File | 1996-08-04 | 13.5 KB | 328 lines

  LILO configuration (LInux LOader)
  Introduction

  11..  PPuurrppoossee

  _L_i_n_u_x may boot using different mechanisms. Booting involve mainly
  reading and bringing a kernel file (often called zImage or vmlinuz) in
  memory, then laughing it. While this sounds all simple, there is
  always some quirks around. This is why booting an Operating System is
  some sort of black art. Unlike many boot loader shipped with some
  other commercial OSs, _L_I_L_O is fully documented and probably the most
  versatile loader ... by far.

  We will first try to describe what's involved and then what you can do
  with all that.

  22..  LLIILLOO pprriinncciipplleess

  Without entering too deep, lets just explain what booting a PC is all
  about.

  22..11..  TThhee ffiirrsstt iinnhhaabbiittaanntt:: TThhee BBIIOOSS

  When a _P_C starts, the first program to take control is the _B_I_O_S which
  is resident in _R_O_M. After initializing most hardware in your machine,
  it will attempt to load a tiny program, either from the first sector
  of the floppy or the first sector of the first hard drive. This
  program is called the _M_a_s_t_e_r _B_o_o_t _R_e_c_o_r_d or _M_B_R for short.

  22..22..  FFrroomm tthhee _M_B_R ooff tthhee hhaarrdd ddrriivvee ttoo tthhee _O_S

  The _M_B_R of the hard drive will locate the active partition and again,
  will load the first sector of that partition. This sector contain a
  tiny little program which knows a little bit more about the internals
  of the _O_S living in that partition. It will proceed to load either
  basic components of the system or simply a more sophisticated boot
  loader which will finish the job.

  22..33..  TThhee ffllooppppyy''ss bboooott sseeccttoorr

  The boot sector of a floppy may be compared to the boot sector of the
  active partition. It will proceed to load the OS living on the floppy.

  22..44..  AAnndd LLIILLOO

  _L_I_L_O is fairly flexible, here is why

  ╖  It can be installed either as a replacement for the _M_B_R or as a
     boot sector, and still boot _L_i_n_u_x or most other OS on any drives in
     any partitions.

  ╖  It can be installed on the boot sector of the floppy and still
     perform its normal task, booting almost anything on the hard
     drive(s).

  ╖  Beside the boot sector, it has no hidden file, nor use any special
     partition. Further, its configuration files can be installed in any
     partition, even unrelated to _L_i_n_u_x, even in a subdirectory of a _D_O_S
     partition.

  ╖  It can boot several different kernel configuration and even several
     different kernels.

  ╖  It can boot more than one _L_i_n_u_x installation.

  ╖  It can boot linux on any drive.

  22..55..  LLIILLOO,, LLiinnuuxx aanndd tthhee wwoorrlldd

  When installing _L_i_n_u_x on a system with several OS (other than _L_i_n_u_x),
  take this as a rule of thumb. Manage to install and boot all the other
  OSs first. They are less flexible.  _L_i_n_u_x will always find it way.

  33..  _L_I_L_O ccoonnffiigguurraattiioonn ddiiaalloogg

  Now that you know a little bit what _L_I_L_O can do, let see how you can
  configure it using _L_i_n_u_x_c_o_n_f. The main configuration dialog is split
  in sections. Here is an introduction to each.

  33..11..  GGlloobbaall ffeeaattuurreess

  This section deal with how to install _L_I_L_O.

  33..11..11..  DDiissaabblliinngg _L_I_L_O

  If you boot your _L_i_n_u_x system without _L_I_L_O, you may find _L_i_n_u_x_c_o_n_f
  behavior a little bit annoying as it try to make sure _L_I_L_O is properly
  setup-ed all the time. You can disable _L_I_L_O support from _L_i_n_u_x_c_o_n_f
  anytime. This only affect _L_i_n_u_x_c_o_n_f though. This does nothing else. It
  won't UN-install _L_I_L_O. It just say to _L_i_n_u_x_c_o_n_f

       "stop checking lilo".

  33..11..22..  IInnssttaallll bboooott sseeccttoorr oonn

  _L_I_L_O is brought to life by firing a tiny tiny program. This program
  must be installed in a strategic location. The pop-up list of this
  field offers you a list of valid choice is order of preference. If
  _L_i_n_u_x is the aaccttiivvee partition it does not matter much. If it is not,
  or your _L_i_n_u_x partition is not on the first hard drive, you must
  install it on either the master boot record of the first drive, or on
  a boot floppy.

  Note that installing the boot sector on a boot floppy is still pretty
  fast as only one sector is read from it. All other files still lives
  in the _L_i_n_u_x partition.

  33..11..33..  BBiiooss bboooott mmooddee

  Known to boot faster. Known not to work on some machines.  I have no
  experience with it.

  33..11..44..  BBoooott ddeellaayy

  _L_I_L_O may boot right away or wait for some time, allowing you to
  intercept the boot sequence. From there you can

  ╖  Boot a different OS or a different configuration.

  ╖  Pass some boot time parameter to the kernel.

  By pressing the SSHHIIFFTT and TTAABB keys at the same time the boot delay is
  disable and ""bboooott::"" prompt will appear.

  A value of 50 is recommended.

  33..11..55..  MMeessssaaggee ffiillee

  You must put the path of a text file. Ideally, the text will be short
  and will fill the screen, leaving the _L_I_L_O prompt at the bottom. This
  is used for the boot floppies of some distributions.

  33..22..  DDeeffaauullttss

  This section provide the default configuration applying the to
  different _L_i_n_u_x configuration following. Entering information here
  avoid repeating it later.

  33..22..11..  RRoooott ppaarrttiittiioonn

  You must tell where your _L_i_n_u_x root partition is sitting.  A pop-up
  list gives you a list of all partitions.

  33..22..22..  RRaamm ddiisskk ssiizzee

  Ram disk are used for installation boot disks. They are seldom used
  for full configuration. Recent development of kernel modules have made
  ram disk runtime configurable. A value of 0 disable the ram disk
  feature.

  33..22..33..  BBoooott mmooddee

  Normally this flags is on. For _U_M_S_D_O_S installation, it is off. _U_M_S_D_O_S
  installation will generally use _l_o_a_d_l_i_n to boot instead of _L_I_L_O
  anyway.

  Unless you really what your doing, then left it to on. Here is why.
  When _L_i_n_u_x boots, in read-only mode, it is allowed to do much
  inspection of the partitions without touching them at all. This is
  good especially if the boot follows a crash which has left the
  partitions in a weird state.

  Why all the fuss about not touching the partition ? Well, _L_i_n_u_x
  support multiple time stamps per file. One is the "last access date".
  This means that the file system is changed (data is written to the
  disk) just by reading files (which is exactly what happen at boot
  time).

  This last access time stamp is pretty useful both becomes a nuisance
  at boot time. The "read only" tells _L_i_n_u_x to drop this behavior.

  After the partition has been checked, the system will set back to
  "read write" mode automatically.

  33..22..44..  BBoooott ooppttiioonnss

  Some drivers required some information to correctly initialized
  themselves. For example, _L_i_n_u_x is probing only for one Ethernet
  adaptor. If you have two, you can write in this field

               ether=11,0x300,eth1

  This will tell _L_i_n_u_x to check for a second adapter (the first being
  eth0) at IIRRQQ 11 and IIOO 300 hex.

  There is a complete document about boot time configuration.  Note that
  the forthcoming _L_i_n_u_x 1.4 will dramatically changed this has run time
  modules will make a widespread appearance.

  The document can be found at ______________.

  33..33..  LLiinnuuxx sseettuuppss

  The default section is followed by several identical sections. Each
  defines one _L_i_n_u_x boot configuration.  Each boot configuration repeats
  all the parameter of the default section. You can simply override them
  here.

  The first configuration will be the default one. This means that _L_I_L_O
  will boot this one unless told differently (Using SHIFT TAB to stop
  the boot process...).

  Only 3 fields differ from the default section.

  33..33..11..  DDeelleettee tthhiiss ccoonnffiigguurraattiioonn

  If you check this box, the configuration will disappear when you will
  hit the aacccceepptt button.

  33..33..22..  KKeerrnneell iimmaaggee ffiillee

  This is the path of the kernel file which will boot for this
  configuration. Note that one kernel file may participate to several
  configurations.

  33..33..33..  LLaabbeell

  This is a short name identifying uniquely the configuration.  Given
  that a kernel file may be shared by several configuration, we need a
  unique key. This will be used when intercepting the boot process. _L_I_L_O
  expect simply a label name and will boot the corresponding
  configuration.

  33..44..  OOtthheerr ooppeerraattiinngg ssyysstteemm

  _L_I_L_O is able to boot almost anything. For each OOSS you want to boot,
  simply specify the partition and a label.  _L_I_L_O simply load the boot
  sector of that partition and launch it.

  44..  MMoovviinngg _L_I_L_O ccoonnffiigguurraattiioonn ffiilleess

  Sometime, one must play with _L_i_l_O's configuration file. The good news
  is that, first, they are movable, the the next good news is that you
  can tell Linuxconf about it.  Just go to the "List all configuration
  files" menu, scroll to the //eettcc//lliilloo..ccoonnff line and select the eeddiitt
  button. Enter the new path of the _L_I_L_O configuration file.  Be aware
  that _L_I_L_O expect to find its configuration file in /etc/lilo.conf.
  When moving the file, it has to go to a subdirectory holding a eettcc
  subdirectory in which you will place the file lliilloo..ccoonnff.

  44..11..  WWhhyy mmoovviinngg _L_I_L_O aannyywwaayy ??

  There are different reason why one would want to do this. Here are
  some.

  ╖  Your hard drive has more that 1024 cylinders and the root partition
     goes beyond. _L_I_L_O uses the BIOS to load the kernel files (among
     other things). If the kernel file lies above the 1024 cylinder
     limit, _L_I_L_O won't be able to boot properly. In fact, LILO will tell
     you right away at install time.

  ╖  You root partition is located on the third or fourth hard drive and
     your BIOS (again) is too old and does not know about this second
     IDE channel. In this case, LILO will warn you at install time that
     some BIOS can't access the drive. At boot time you will get a bunch
     of errors.

  44..22..  HHooww ttoo mmoovvee ?? WWhheerree ??

  On a machine dedicated to Linux, where you have a large drive with
  more than 1024 cylinder, many people will create a smaller partition
  for the basic OS and a larger for the data, insuring that all LILO
  file fits under the 1024 cylinder limit.

  This is often annoying as it makes management more complex.  You end
  up with two partition partly filled.

  Another solution is to create a very small partition (few megs) at the
  beginning of the disk and reserve that for _L_I_L_O configuration and
  kernel files. This way you can create a single large root partition
  which is nicer to manage.

  (one can argue that creating a single large partition is a bad idea as
  it puts all the eggs in the same bag. Given the design of the EEXXTT22
  file system which distribute management information all over the
  partition, with replication, I doubt this apply anymore).

  So you have a partition which fits the bill. It is all accessible from
  the BIOS. Here are the steps to follow. Suppose this partition in
  mount under the lliilloo directory and you want to put all configuration
  files in the root of this partition.

  ╖  mkdir /lilo/etc

  ╖  cp /etc/lilo.conf /lilo/etc/lilo.conf

  ╖  mkdir /lilo/boot

  ╖  cp /boot/* /lilo/boot

  ╖  cd /

  ╖  tar cf - dev | (cd /lilo && tar xvf -)

  ╖  cp /vmlinuz /lilo

  You can activate this moved configuration like this

               /sbin/lilo -r /lilo

  And you can do this with Linuxconf by telling the //eettcc//lliilloo..ccoonnff is
  now //lliilloo//eettcc//lliilloo..ccoonnff.  From now on, using Linuxconf, this should be
  completely invisible to you or whoever manage your machine.

  55..  AAlltteerrnnaattiivveess ttoo LLIILLOO

  _L_i_n_u_x can be boot from a plain floppy or using loadlin.  All this is
  unrelated to _L_I_L_O but it is good to know about it.  Assuming your
  _L_i_n_u_x root partition is /dev/hdaX...

  55..11..  UUssiinngg aa ffllooppppyy

  To create a simple boot floppy, just to this

  ╖  cp zImage /dev/fd0

  ╖  rdev /dev/fd0 /dev/hdaX

  ╖  rdev -R /dev/fd0 1

  55..22..  UUssiinngg llooaaddlliinn

  To boot with loadlin (A _D_O_S program), just copy the kernel file to
  your _D_O_S partition and type, at the _D_O_S prompt:

  loadlin zimage root=/dev/hdaX ro