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        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.

 - The Documentation/DocBook/ subdirectory contains several guides for

   kernel developers and users.  These guides can be rendered in a

   number of formats:  PostScript (.ps), PDF, and HTML, among others.

   After installation, "make psdocs", "make pdfdocs", or "make htmldocs"

   will render the documentation in the requested format.

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

   top level directory of the kernel source (linux-2.4.xx) and execute:

               gzip -cd ../patch-2.4.xx.gz | patch -p1

   or

               bzip2 -dc ../patch-2.4.xx.bz2 | patch -p1

   (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 2.95.3 available.  gcc 2.91.66 (egcs-1.1.2) 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 .

 - 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.

   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.