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        Linux kernel release 2.0.xx

These are the release notes for linux version 2.0.  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 DEC Alphas, SUN Sparcs, M68000 machines (like Atari and Amiga),

  MIPS and PowerPC.

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's in the kernel 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.

INSTALLING the kernel:

 - If you install the full sources, do a

                cd /usr/src

                gzip -cd linux-2.0.XX.tar.gz | tar xfv -

   to get it all put in place. Replace "XX" with the version number of the

   latest kernel. If you use GNU tar,

                cd /usr/src

                tar -xzvf linux-2.1.XX.tar.gz

   is equivalent.

 - You can also upgrade between 2.0.xx releases by patching.  Each

   patch that is released for 2.0.xx contains only bugfixes.  No

   new features will be added to the Linux kernel until the 2.1.xx

   development effort begins.  To install by patching, get all the

   newer patch files and do

                cd /usr/src

                gzip -cd patchXX.gz | 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.

                cd /usr/src

                linux/scripts/patch-kernel

   The default directory for the kernel source is /usr/src/linux, but

   can be specified as the first argument.  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 /usr/src/linux

                make mrproper

   You should now have the sources correctly installed.

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 hopefully one of those is correct.

 - Alternate configuration commands are:

        "make menuconfig"  Text based color menus, radiolists & dialogs.

        "make xconfig"     X windows based configuration tool.

        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 a "production"

          kernel.

 - 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-2.6.3 or newer available.  It seems older gcc

   versions can have problems compiling newer versions of linux.  If you

   upgrade your compiler, remember to get the new binutils package too

   (for as/ld/nm and company).

 - do a "make zImage" to create a compressed kernel image.  If you want

   to make a bootdisk (without root filesystem or lilo), insert a floppy

   in your A: drive, and do a "make zdisk".  It is also possible to do

   "make zlilo" if you have lilo installed to suit the kernel makefiles,

   but you may want to check your particular lilo setup first.

 - if your kernel is too large for "make zImage", use "make bzImage"

   instead.

 - 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.

 - In order to boot your new kernel, you'll need to copy the kernel

   image (found in /usr/src/linux/arch/i386/boot/zImage 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 "cp

   /usr/src/linux/arch/i386/boot/zImage /dev/fd0" to make a bootable

   floppy.  Note that as of Linux 2.0.0, a kernel copied to a 720k

   double-density 3.5" floppy disk no longer boots.  In this case,

   it is highly recommended that you install LILO on your

   double-density bootfloppy 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, or /zImage, or /etc/zImage.

   To use the new kernel, copy the new image over the old one (save a

   backup of the original!).  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 (Linus.Torvalds@Helsinki.FI), 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.  Find

   the C++ sources under the scripts/ directory to avoid having to 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.