README

	Linux kernel release 0.99 patchlevel 12

These are the release notes for linux version 0.99.12.  Read them
carefully, as they tell you what's new, explain how to install the
kernel, and what to do if something goes wrong. 

NOTE! There has been some indication that gcc versions older than 2.4.5
result in bad kernels being built: 2.3.3 will fail even to build the
kernel, and I have at least one report of trouble with a 2.4.3-built
kernel that went away when the kernel was recompiled with 2.4.5. 

CHANGES since 0.99 patchlevel 11 and earlier:

 - The memory manager cleanup has continued, and seems to be mostly
   ready, as proven by the ease of adding mmap() over NFS with the new
   routines.  So yes, the pl12 kernel will demand-load your binaries
   over NFS, sharing code and clean data, as well as running shared
   libraries over NFS.  Memory management by Eric and me, while the NFS
   mmap code was written by Jon Tombs,

 - ** IMPORTANT **: The keyboard driver has been enhanced even further,
   and almost everything is completely re-mappable.  This means that
   there is a new version of 'loadkeys' and 'dumpkeys' that you must use
   with this kernel or you'll have problems.  The default keyboard is
   still the US mapping, but if you want to create your own mappings
   you'll have to load them with the new binaries.  Get the 'kbd.tar.gz'
   archive from the same place you get the kernel. 

   The new keymappings allow things like function key string changes,
   remapping of the control keys, and freedom to remap any of the normal
   keyboard functions: including special features like rebooting,
   console switching etc.  The keyboard remapping code has been done
   mostly by Risto Kankkunen (Risto.Kankkunen@Helsinki.FI). 

 - updated network drivers by Donald Becker

 - updated serial drivers - tytso@Athena.mit.edu

 - updated 387 emulation (Bill Metzenthen).  The updated emulator code
   has more exact trigonometric functions and improved exception
   handling.  It now behaves very much like a real 486, with only small
   changes (greater accuracy, slightly different denormal NaN handling
   etc - hard to detect the differences even if you are looking for
   them). 

 - network timer fixes by Florian La Roche (much cleaned up net/inet/timer.c
   and some bad race-conditions fixed).

 - Scsi code updates by Eric Youngdale and others

 - Sony CDU-31A CDROM driver by Corey Minyard added to the standard
   kernel distribution. 

 - The Mitsumi CDROM driver is now part of the standard kernel.  Driver
   by Martin Harriss with patches by stud11@cc4.kuleuven.ac.be (yes, he
   probably has a real name, but no, I haven't found it) and Jon Tombs. 

 - various other minor patches (preliminary ldt support etc)

NOTABLE changes since patchlevel 10 or earlier:

 - The memory manager has been cleaned up substantially, and mmap()
   works for MAP_PRIVATE.  MAP_SHARED is still not supported for
   anything else than /dev/mem, but even so it actually is usable for a
   lot of applications.  The shared library routines have been rewritten
   to use mmap() instead of the old hardcoded behaviour. 

 - The kernel is now compiled with C++ instead of plain C.  Very few
   actual C++ features are used, but even so C++ allows for more
   type-checking and type-safe linkage. 

 - The filesystem routines have been cleaned up for multiple block
   sizes.  None of the filesystems use it yet, but people are working on
   it. 

 - named pipes and normal pipes should hopefully have the right select()
   semantics in the presense/absense of writers. 

 - QIC-02 tape driver by Hennus Bergman

 - selection patches in the default kernel

 - fixed a bug in the pty code which led to busy waiting in some
   circumstances instead of sleeping. 

 - Compressed SLIP support (Charles Hedrick). See net/inet/CONFIG

 - the 'clear_bit()' function was changed to return the previous setting
   of the bit instead of the old "error-code".  This makes use of the
   bit operations more logical. 

 - udelay() function for short delays (busy-waiting) added.  Used
   currently only by the QIC driver. 

 - fork() and sheduler changes to make task switches happen only from
   kernel mode to kernel mode.  Cleaner and more portable than the old
   code which counted on being able to task-switch directly into user
   mode. 

 - debugging malloc code.

INSTALLING the kernel:

 - if you install by patching, you need a *clean* 0.99.11 source tree,
   which presumably exists in /usr/src/linux.  If so, to get the kernel
   patched, just do a

		cd /usr/src
		patch -p0 < linux-0.99.patch12

   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 you install the full sources, do a

		cd /usr/src
		tar xvf linux-0.99.12.tar

   to get it all put in place.

 - make sure your /usr/include/linux and /usr/include/asm directories
   are just symlinks to the kernel sources:

		cd /usr/include
		rm -rf linux
		rm -rf asm
		ln -s /usr/src/linux/include/linux .
		ln -s /usr/src/linux/include/asm .

 - 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. 

	NOTES on "make config":
	- compiling the kernel with "-m486" for a number of 486-specific
	  will result in a kernel that still works on a 386: it may be
	  slightly larger and possibly slower by an insignificant amount,
	  but it should not hurt performance. 
	- 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 slighly 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. 

 - edit net/inet/CONFIG to configure the networking parts of the kernel. 
   The comments should hopefully clarify it all. 

 - 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-2.4.5 or newer available with g++.  It seems
   older gcc versions can have problems compiling linux 0.99.10 and
   newer versions.  If you upgrade, 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. 

 - keep a backup kernel handy in case something goes wrong. 

 - reboot with the new kernel and enjoy. 

IF SOMETHING GOES WRONG:

 - if you have problems that seem to be due to kernel bugs, please 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)

 - in debugging dumps like the above, it helps enourmously 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.  In the
   case of compressed kernels, this will be 'linux/tools/zSystem', while
   uncompressed kernels use the file 'tools/system'.  To extract the
   namelist and match it against the EIP from the kernel crash, do:

		nm tools/zSystem | 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.