[PATCH] VFS: split dentry locking documentation

[linux-2.6/kmemtrace.git] / Documentation / Changes

Intro
=====

This document is designed to provide a list of the minimum levels of
software necessary to run the 2.6 kernels, as well as provide brief
instructions regarding any other "Gotchas" users may encounter when
trying life on the Bleeding Edge.  If upgrading from a pre-2.4.x
kernel, please consult the Changes file included with 2.4.x kernels for
additional information; most of that information will not be repeated
here.  Basically, this document assumes that your system is already
functional and running at least 2.4.x kernels.

This document is originally based on my "Changes" file for 2.0.x kernels
and therefore owes credit to the same people as that file (Jared Mauch,
Axel Boldt, Alessandro Sigala, and countless other users all over the
'net).

The latest revision of this document, in various formats, can always
be found at <http://cyberbuzz.gatech.edu/kaboom/linux/Changes-2.4/>.

Feel free to translate this document.  If you do so, please send me a
URL to your translation for inclusion in future revisions of this
document.

Smotrite file <http://oblom.rnc.ru/linux/kernel/Changes.ru>, yavlyaushisya
russkim perevodom dannogo documenta.

Visite <http://www2.adi.uam.es/~ender/tecnico/> para obtener la traducción
al español de este documento en varios formatos.

Eine deutsche Version dieser Datei finden Sie unter
<http://www.stefan-winter.de/Changes-2.4.0.txt>.

Last updated: October 29th, 2002

Chris Ricker (kaboom@gatech.edu or chris.ricker@genetics.utah.edu).

Current Minimal Requirements
============================

Upgrade to at *least* these software revisions before thinking you've
encountered a bug!  If you're unsure what version you're currently
running, the suggested command should tell you.

Again, keep in mind that this list assumes you are already
functionally running a Linux 2.4 kernel.  Also, not all tools are
necessary on all systems; obviously, if you don't have any ISDN
hardware, for example, you probably needn't concern yourself with
isdn4k-utils.

o  Gnu C                  2.95.3                  # gcc --version
o  Gnu make               3.79.1                  # make --version
o  binutils               2.12                    # ld -v
o  util-linux             2.10o                   # fdformat --version
o  module-init-tools      0.9.10                  # depmod -V
o  e2fsprogs              1.29                    # tune2fs
o  jfsutils               1.1.3                   # fsck.jfs -V
o  reiserfsprogs          3.6.3                   # reiserfsck -V 2>&1|grep reiserfsprogs
o  xfsprogs               2.6.0                   # xfs_db -V
o  pcmciautils            004
o  pcmcia-cs              3.1.21                  # cardmgr -V
o  quota-tools            3.09                    # quota -V
o  PPP                    2.4.0                   # pppd --version
o  isdn4k-utils           3.1pre1                 # isdnctrl 2>&1|grep version
o  nfs-utils              1.0.5                   # showmount --version
o  procps                 3.2.0                   # ps --version
o  oprofile               0.9                     # oprofiled --version
o  udev                   071                     # udevinfo -V

Kernel compilation
==================

GCC
---

The gcc version requirements may vary depending on the type of CPU in your
computer. The next paragraph applies to users of x86 CPUs, but not
necessarily to users of other CPUs. Users of other CPUs should obtain
information about their gcc version requirements from another source.

The recommended compiler for the kernel is gcc 2.95.x (x >= 3), and it
should be used when you need absolute stability. You may use gcc 3.0.x
instead if you wish, although it may cause problems. Later versions of gcc 
have not received much testing for Linux kernel compilation, and there are 
almost certainly bugs (mainly, but not exclusively, in the kernel) that
will need to be fixed in order to use these compilers. In any case, using
pgcc instead of plain gcc is just asking for trouble.

The Red Hat gcc 2.96 compiler subtree can also be used to build this tree.
You should ensure you use gcc-2.96-74 or later. gcc-2.96-54 will not build
the kernel correctly.

In addition, please pay attention to compiler optimization.  Anything
greater than -O2 may not be wise.  Similarly, if you choose to use gcc-2.95.x
or derivatives, be sure not to use -fstrict-aliasing (which, depending on
your version of gcc 2.95.x, may necessitate using -fno-strict-aliasing).

Make
----

You will need Gnu make 3.79.1 or later to build the kernel.

Binutils
--------

Linux on IA-32 has recently switched from using as86 to using gas for
assembling the 16-bit boot code, removing the need for as86 to compile
your kernel.  This change does, however, mean that you need a recent
release of binutils.

System utilities
================

Architectural changes
---------------------

DevFS has been obsoleted in favour of udev
(http://www.kernel.org/pub/linux/utils/kernel/hotplug/)

32-bit UID support is now in place.  Have fun!

Linux documentation for functions is transitioning to inline
documentation via specially-formatted comments near their
definitions in the source.  These comments can be combined with the
SGML templates in the Documentation/DocBook directory to make DocBook
files, which can then be converted by DocBook stylesheets to PostScript,
HTML, PDF files, and several other formats.  In order to convert from
DocBook format to a format of your choice, you'll need to install Jade as
well as the desired DocBook stylesheets.

Util-linux
----------

New versions of util-linux provide *fdisk support for larger disks,
support new options to mount, recognize more supported partition
types, have a fdformat which works with 2.4 kernels, and similar goodies.
You'll probably want to upgrade.

Ksymoops
--------

If the unthinkable happens and your kernel oopses, you may need the
ksymoops tool to decode it, but in most cases you don't.
In the 2.6 kernel it is generally preferred to build the kernel with
CONFIG_KALLSYMS so that it produces readable dumps that can be used as-is
(this also produces better output than ksymoops).
If for some reason your kernel is not build with CONFIG_KALLSYMS and
you have no way to rebuild and reproduce the Oops with that option, then
you can still decode that Oops with ksymoops.

Module-Init-Tools
-----------------

A new module loader is now in the kernel that requires module-init-tools
to use.  It is backward compatible with the 2.4.x series kernels.

Mkinitrd
--------

These changes to the /lib/modules file tree layout also require that
mkinitrd be upgraded.

E2fsprogs
---------

The latest version of e2fsprogs fixes several bugs in fsck and
debugfs.  Obviously, it's a good idea to upgrade.

JFSutils
--------

The jfsutils package contains the utilities for the file system.
The following utilities are available:
o fsck.jfs - initiate replay of the transaction log, and check
  and repair a JFS formatted partition.
o mkfs.jfs - create a JFS formatted partition.
o other file system utilities are also available in this package.

Reiserfsprogs
-------------

The reiserfsprogs package should be used for reiserfs-3.6.x
(Linux kernels 2.4.x). It is a combined package and contains working
versions of mkreiserfs, resize_reiserfs, debugreiserfs and
reiserfsck. These utils work on both i386 and alpha platforms.

Xfsprogs
--------

The latest version of xfsprogs contains mkfs.xfs, xfs_db, and the
xfs_repair utilities, among others, for the XFS filesystem.  It is
architecture independent and any version from 2.0.0 onward should
work correctly with this version of the XFS kernel code (2.6.0 or
later is recommended, due to some significant improvements).

PCMCIAutils
-----------

PCMCIAutils replaces pcmcia-cs (see below). It properly sets up
PCMCIA sockets at system startup and loads the appropriate modules
for 16-bit PCMCIA devices if the kernel is modularized and the hotplug
subsystem is used.

Pcmcia-cs
---------

PCMCIA (PC Card) support is now partially implemented in the main
kernel source. The "pcmciautils" package (see above) replaces pcmcia-cs
for newest kernels.

Quota-tools
-----------

Support for 32 bit uid's and gid's is required if you want to use
the newer version 2 quota format.  Quota-tools version 3.07 and
newer has this support.  Use the recommended version or newer
from the table above.

Intel IA32 microcode
--------------------

A driver has been added to allow updating of Intel IA32 microcode,
accessible as both a devfs regular file and as a normal (misc)
character device.  If you are not using devfs you may need to:

mkdir /dev/cpu
mknod /dev/cpu/microcode c 10 184
chmod 0644 /dev/cpu/microcode

as root before you can use this.  You'll probably also want to
get the user-space microcode_ctl utility to use with this.

Powertweak
----------

If you are running v0.1.17 or earlier, you should upgrade to
version v0.99.0 or higher. Running old versions may cause problems
with programs using shared memory.

udev
----
udev is a userspace application for populating /dev dynamically with
only entries for devices actually present. udev replaces devfs.

FUSE
----

Needs libfuse 2.4.0 or later.  Absolute minimum is 2.3.0 but mount
options 'direct_io' and 'kernel_cache' won't work.

Networking
==========

General changes
---------------

If you have advanced network configuration needs, you should probably
consider using the network tools from ip-route2.

Packet Filter / NAT
-------------------
The packet filtering and NAT code uses the same tools like the previous 2.4.x
kernel series (iptables).  It still includes backwards-compatibility modules
for 2.2.x-style ipchains and 2.0.x-style ipfwadm.

PPP
---

The PPP driver has been restructured to support multilink and to
enable it to operate over diverse media layers.  If you use PPP,
upgrade pppd to at least 2.4.0.

If you are not using devfs, you must have the device file /dev/ppp
which can be made by:

mknod /dev/ppp c 108 0

as root.

If you use devfsd and build ppp support as modules, you will need
the following in your /etc/devfsd.conf file:

LOOKUP  PPP     MODLOAD

Isdn4k-utils
------------

Due to changes in the length of the phone number field, isdn4k-utils
needs to be recompiled or (preferably) upgraded.

NFS-utils
---------

In 2.4 and earlier kernels, the nfs server needed to know about any
client that expected to be able to access files via NFS.  This
information would be given to the kernel by "mountd" when the client
mounted the filesystem, or by "exportfs" at system startup.  exportfs
would take information about active clients from /var/lib/nfs/rmtab.

This approach is quite fragile as it depends on rmtab being correct
which is not always easy, particularly when trying to implement
fail-over.  Even when the system is working well, rmtab suffers from
getting lots of old entries that never get removed.

With 2.6 we have the option of having the kernel tell mountd when it
gets a request from an unknown host, and mountd can give appropriate
export information to the kernel.  This removes the dependency on
rmtab and means that the kernel only needs to know about currently
active clients.

To enable this new functionality, you need to:

  mount -t nfsd nfsd /proc/fs/nfs

before running exportfs or mountd.  It is recommended that all NFS
services be protected from the internet-at-large by a firewall where
that is possible.

Getting updated software
========================

Kernel compilation
******************

gcc 2.95.3
----------
o  <ftp://ftp.gnu.org/gnu/gcc/gcc-2.95.3.tar.gz>

Make
----
o  <ftp://ftp.gnu.org/gnu/make/>

Binutils
--------
o  <ftp://ftp.kernel.org/pub/linux/devel/binutils/>

System utilities
****************

Util-linux
----------
o  <ftp://ftp.kernel.org/pub/linux/utils/util-linux/>

Ksymoops
--------
o  <ftp://ftp.kernel.org/pub/linux/utils/kernel/ksymoops/v2.4/>

Module-Init-Tools
-----------------
o  <ftp://ftp.kernel.org/pub/linux/kernel/people/rusty/modules/>

Mkinitrd
--------
o  <ftp://rawhide.redhat.com/pub/rawhide/SRPMS/SRPMS/>

E2fsprogs
---------
o  <http://prdownloads.sourceforge.net/e2fsprogs/e2fsprogs-1.29.tar.gz>

JFSutils
--------
o  <http://jfs.sourceforge.net/>

Reiserfsprogs
-------------
o  <http://www.namesys.com/pub/reiserfsprogs/reiserfsprogs-3.6.3.tar.gz>

Xfsprogs
--------
o  <ftp://oss.sgi.com/projects/xfs/download/>

Pcmciautils
-----------
o  <ftp://ftp.kernel.org/pub/linux/utils/kernel/pcmcia/>

Pcmcia-cs
---------
o  <http://pcmcia-cs.sourceforge.net/>

Quota-tools
----------
o  <http://sourceforge.net/projects/linuxquota/>

DocBook Stylesheets
-------------------
o  <http://nwalsh.com/docbook/dsssl/>

XMLTO XSLT Frontend
-------------------
o  <http://cyberelk.net/tim/xmlto/>

Intel P6 microcode
------------------
o  <http://www.urbanmyth.org/microcode/>

Powertweak
----------
o  <http://powertweak.sourceforge.net/>

udev
----
o <http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html>

FUSE
----
o <http://sourceforge.net/projects/fuse>

Networking
**********

PPP
---
o  <ftp://ftp.samba.org/pub/ppp/ppp-2.4.0.tar.gz>

Isdn4k-utils
------------
o  <ftp://ftp.isdn4linux.de/pub/isdn4linux/utils/isdn4k-utils.v3.1pre1.tar.gz>

NFS-utils
---------
o  <http://sourceforge.net/project/showfiles.php?group_id=14>

Iptables
--------
o  <http://www.iptables.org/downloads.html>

Ip-route2
---------
o  <ftp://ftp.tux.org/pub/net/ip-routing/iproute2-2.2.4-now-ss991023.tar.gz>

OProfile
--------
o  <http://oprofile.sf.net/download/>

NFS-Utils
---------
o  <http://nfs.sourceforge.net/>