lienze/linux_2.4.0

Linux kernel release 2.4.xx

These are the release notes for Linux version 2.4. Read them carefully,
as they tell you what this is all about, explain how to install the
kernel, and what to do if something goes wrong.

WHAT IS LINUX?

Linux is a Unix clone written from scratch by Linus Torvalds with
assistance from a loosely-knit team of hackers across the Net.
It aims towards POSIX compliance.

It has all the features you would expect in a modern fully-fledged
Unix, including true multitasking, virtual memory, shared libraries,
demand loading, shared copy-on-write executables, proper memory
management and TCP/IP networking.

It is distributed under the GNU General Public License - see the
accompanying COPYING file for more details.

ON WHAT HARDWARE DOES IT RUN?

Linux was first developed for 386/486-based PCs. These days it also
runs on ARMs, DEC Alphas, SUN Sparcs, M68000 machines (like Atari and
Amiga), MIPS and PowerPC, and others.

DOCUMENTATION:

• There is a lot of documentation available both in electronic form on
  the Internet and in books, both Linux-specific and pertaining to
  general UNIX questions. I'd recommend looking into the documentation
  subdirectories on any Linux FTP site for the LDP (Linux Documentation
  Project) books. This README is not meant to be documentation on the
  system: there are much better sources available.

• There are various README files in the Documentation/ subdirectory:
  these typically contain kernel-specific installation notes for some
  drivers for example. See ./Documentation/00-INDEX for a list of what
  is contained in each file. Please read the Changes file, as it
  contains information about the problems, which may result by upgrading
  your kernel.

INSTALLING the kernel:

• If you install the full sources, put the kernel tarball in a
  directory where you have permissions (eg. your home directory) and
  unpack it:

   gzip -cd linux-2.4.XX.tar.gz | tar xvf -
  

  Replace "XX" with the version number of the latest kernel.

  Do NOT use the /usr/src/linux area! This area has a (usually
  incomplete) set of kernel headers that are used by the library header
  files. They should match the library, and not get messed up by
  whatever the kernel-du-jour happens to be.

• You can also upgrade between 2.4.xx releases by patching. Patches are
  distributed in the traditional gzip and the new bzip2 format. To
  install by patching, get all the newer patch files, enter the
  directory in which you unpacked the kernel source and execute:

   gzip -cd patchXX.gz | patch -p0
  

  or
  bzip2 -dc patchXX.bz2 | patch -p0

  (repeat xx for all versions bigger than the version of your current
  source tree, in_order) and you should be ok. You may want to remove
  the backup files (xxx~ or xxx.orig), and make sure that there are no
  failed patches (xxx# or xxx.rej). If there are, either you or me has
  made a mistake.

  Alternatively, the script patch-kernel can be used to automate this
  process. It determines the current kernel version and applies any
  patches found.

   linux/scripts/patch-kernel linux
  

  The first argument in the command above is the location of the
  kernel source. Patches are applied from the current directory, but
  an alternative directory can be specified as the second argument.

• Make sure you have no stale .o files and dependencies lying around:

   cd linux
   make mrproper
  

  You should now have the sources correctly installed.

SOFTWARE REQUIREMENTS

Compiling and running the 2.4.xx kernels requires up-to-date
versions of various software packages. Consult
./Documentation/Changes for the minimum version numbers required
and how to get updates for these packages. Beware that using
excessively old versions of these packages can cause indirect
errors that are very difficult to track down, so don't assume that
you can just update packages when obvious problems arise during
build or operation.

CONFIGURING the kernel:

• Do a "make config" to configure the basic kernel. "make config" needs
  bash to work: it will search for bash in $BASH, /bin/bash and /bin/sh
  (in that order), so one of those must be correct for it to work.

  Do not skip this step even if you are only upgrading one minor
  version. New configuration options are added in each release, and
  odd problems will turn up if the configuration files are not set up
  as expected. If you want to carry your existing configuration to a
  new version with minimal work, use "make oldconfig", which will
  only ask you for the answers to new questions.

• Alternate configuration commands are:
  "make menuconfig" Text based color menus, radiolists & dialogs.
  "make xconfig" X windows based configuration tool.
  "make oldconfig" Default all questions based on the contents of
  your existing ./.config file.

  NOTES on "make config":

  • having unnecessary drivers will make the kernel bigger, and can
    under some circumstances lead to problems: probing for a
    nonexistent controller card may confuse your other controllers
  • compiling the kernel with "Processor type" set higher than 386
    will result in a kernel that does NOT work on a 386. The
    kernel will detect this on bootup, and give up.
  • A kernel with math-emulation compiled in will still use the
    coprocessor if one is present: the math emulation will just
    never get used in that case. The kernel will be slightly larger,
    but will work on different machines regardless of whether they
    have a math coprocessor or not.
  • the "kernel hacking" configuration details usually result in a
    bigger or slower kernel (or both), and can even make the kernel
    less stable by configuring some routines to actively try to
    break bad code to find kernel problems (kmalloc()). Thus you
    should probably answer 'n' to the questions for
    "development", "experimental", or "debugging" features.

• Check the top Makefile for further site-dependent configuration
  (default SVGA mode etc).

• Finally, do a "make dep" to set up all the dependencies correctly.

COMPILING the kernel:

• Make sure you have gcc-2.91.66 (egcs-1.1.2) available. gcc 2.95.2 may
  also work but is not as safe, and gcc 2.7.2.3 is no longer supported.
  Also remember to upgrade your binutils package (for as/ld/nm and company)
  if necessary. For more information, refer to ./Documentation/Changes.

  Please note that you can still run a.out user programs with this
  kernel.

• Do a "make bzImage" to create a compressed kernel image. If you want
  to make a boot disk (without root filesystem or LILO), insert a floppy
  in your A: drive, and do a "make bzdisk". It is also possible to do
  "make install" if you have lilo installed to suit the kernel makefiles,
  but you may want to check your particular lilo setup first.

  To do the actual install you have to be root, but none of the normal
  build should require that. Don't take the name of root in vain.

• In the unlikely event that your system cannot boot bzImage kernels you
  can still compile your kernel as zImage. However, since zImage support
  will be removed at some point in the future in favor of bzImage we
  encourage people having problems with booting bzImage kernels to report
  these, with detailed hardware configuration information, to the
  linux-kernel mailing list and to H. Peter Anvin hpa+linux@zytor.com.

• If you configured any of the parts of the kernel as `modules', you
  will have to do "make modules" followed by "make modules_install".
  Read Documentation/modules.txt for more information. For example,
  an explanation of how to use the modules is included there.

• Keep a backup kernel handy in case something goes wrong. This is
  especially true for the development releases, since each new release
  contains new code which has not been debugged. Make sure you keep a
  backup of the modules corresponding to that kernel, as well. If you
  are installing a new kernel with the same version number as your
  working kernel, make a backup of your modules directory before you
  do a "make modules_install".

• In order to boot your new kernel, you'll need to copy the kernel
  image (found in .../linux/arch/i386/boot/bzImage after compilation)
  to the place where your regular bootable kernel is found.

  For some, this is on a floppy disk, in which case you can copy the
  kernel bzImage file to /dev/fd0 to make a bootable floppy. Please note
  that you can not boot a kernel by directly dumping it to a 720k
  double-density 3.5" floppy. In this case, it is highly recommended
  that you install LILO on your double-density boot floppy or switch to
  high-density floppies.

  If you boot Linux from the hard drive, chances are you use LILO which
  uses the kernel image as specified in the file /etc/lilo.conf. The
  kernel image file is usually /vmlinuz, /boot/vmlinuz, /bzImage or
  /boot/bzImage. To use the new kernel, save a copy of the old image
  and copy the new image over the old one. Then, you MUST RERUN LILO
  to update the loading map!! If you don't, you won't be able to boot
  the new kernel image.

  Reinstalling LILO is usually a matter of running /sbin/lilo.
  You may wish to edit /etc/lilo.conf to specify an entry for your
  old kernel image (say, /vmlinux.old) in case the new one does not
  work. See the LILO docs for more information.

  After reinstalling LILO, you should be all set. Shutdown the system,
  reboot, and enjoy!

  If you ever need to change the default root device, video mode,
  ramdisk size, etc. in the kernel image, use the 'rdev' program (or
  alternatively the LILO boot options when appropriate). No need to
  recompile the kernel to change these parameters.

• Reboot with the new kernel and enjoy.

IF SOMETHING GOES WRONG:

• If you have problems that seem to be due to kernel bugs, please check
  the file MAINTAINERS to see if there is a particular person associated
  with the part of the kernel that you are having trouble with. If there
  isn't anyone listed there, then the second best thing is to mail
  them to me (torvalds@transmeta.com), and possibly to any other
  relevant mailing-list or to the newsgroup. The mailing-lists are
  useful especially for SCSI and networking problems, as I can't test
  either of those personally anyway.

• In all bug-reports, please tell what kernel you are talking about,
  how to duplicate the problem, and what your setup is (use your common
  sense). If the problem is new, tell me so, and if the problem is
  old, please try to tell me when you first noticed it.

• If the bug results in a message like

  unable to handle kernel paging request at address C0000010
  Oops: 0002
  EIP: 0010:XXXXXXXX
  eax: xxxxxxxx ebx: xxxxxxxx ecx: xxxxxxxx edx: xxxxxxxx
  esi: xxxxxxxx edi: xxxxxxxx ebp: xxxxxxxx
  ds: xxxx es: xxxx fs: xxxx gs: xxxx
  Pid: xx, process nr: xx
  xx xx xx xx xx xx xx xx xx xx

  or similar kernel debugging information on your screen or in your
  system log, please duplicate it exactly. The dump may look
  incomprehensible to you, but it does contain information that may
  help debugging the problem. The text above the dump is also
  important: it tells something about why the kernel dumped code (in
  the above example it's due to a bad kernel pointer). More information
  on making sense of the dump is in Documentation/oops-tracing.txt

• You can use the "ksymoops" program to make sense of the dump. This
  utility can be downloaded from
  ftp://ftp..kernel.org/pub/linux/utils/kernel/ksymoops.
  Alternately you can do the dump lookup by hand:

• In debugging dumps like the above, it helps enormously if you can
  look up what the EIP value means. The hex value as such doesn't help
  me or anybody else very much: it will depend on your particular
  kernel setup. What you should do is take the hex value from the EIP
  line (ignore the "0010:"), and look it up in the kernel namelist to
  see which kernel function contains the offending address.

  To find out the kernel function name, you'll need to find the system
  binary associated with the kernel that exhibited the symptom. This is
  the file 'linux/vmlinux'. To extract the namelist and match it against
  the EIP from the kernel crash, do:

   nm vmlinux | sort | less
  

  This will give you a list of kernel addresses sorted in ascending
  order, from which it is simple to find the function that contains the
  offending address. Note that the address given by the kernel
  debugging messages will not necessarily match exactly with the
  function addresses (in fact, that is very unlikely), so you can't
  just 'grep' the list: the list will, however, give you the starting
  point of each kernel function, so by looking for the function that
  has a starting address lower than the one you are searching for but
  is followed by a function with a higher address you will find the one
  you want. In fact, it may be a good idea to include a bit of
  "context" in your problem report, giving a few lines around the
  interesting one.

  If you for some reason cannot do the above (you have a pre-compiled
  kernel image or similar), telling me as much about your setup as
  possible will help.

• Alternately, you can use gdb on a running kernel. (read-only; i.e. you
  cannot change values or set break points.) To do this, first compile the
  kernel with -g; edit arch/i386/Makefile appropriately, then do a "make
  clean". You'll also need to enable CONFIG_PROC_FS (via "make config").

  After you've rebooted with the new kernel, do "gdb vmlinux /proc/kcore".
  You can now use all the usual gdb commands. The command to look up the
  point where your system crashed is "l *0xXXXXXXXX". (Replace the XXXes
  with the EIP value.)

  gdb'ing a non-running kernel currently fails because gdb (wrongly)
  disregards the starting offset for which the kernel is compiled.