root/lm-sensors/trunk/INSTALL @ 619

These are the installation instruction for the lm_sensors package.

There are two ways in which you can compile and install this package. Each
has its own strong points. They are:
 1. Complete separate from kernel compilation
    This will generate a set of modules which can be inserted and removed
    as needed; nothing will be written into the kernel tree;
 2. Patching of the kernel
    This will patch your kernel source tree. You must recompile your kernel
    to take advantage of this. But it makes it possible to compile drivers
    into the kernel itself, instead of having to add them as modules.
    AFTER YOU COMPILED AND INSTALLED YOUR KERNEL, YOU WILL STILL HAVE TO 
    COMPILE THIS PACKAGE TO GET THE USERLAND UTILITIES!

Each of these ways will be described below in detail.

NOTE: OPTION 2 WILL CURRENTLY NOT WORK FOR 2.0 AND OLDER 2.1 KERNELS!

NOTE: IN EACH CASE, YOU WILL HAVE TO GET AND INSTALL THE I2C PACKAGE FIRST!
      SET COMPILE_KERNEL TO 0 IN THE MAIN MAKEFILE FOR OPTION 2!

NOTE: PLEASE READ THE DOCUMENTATION IN THE DOC SUBDIRECTORY IF YOU GET STUCK!


Installing the i2c package
==========================

As of version 2.4.0 of lm_sensors, all i2c components are distributed in
a separate package. There are install instructions in that package. If
you want to use compilation option 2 (patching the kernel) for lm_sensors,
you will have to use compilation option 3 (patching the kernel) for i2c
too. If you want to use compilation option 1 (compiling as modules) for
lm_sensors, you may use either compilation option 1 or 2 (compiling as
modules) or compilation option 3 (patching the kernel for i2c). See the
table below.

                                          LM_SENSORS
I2C                      | option 1 (modules)      option 2 (patch kernel)
option 1 (modules)       |      YES                      NO
option 2 (modules)       |      YES                      YES
option 3 (patch kernel)  |      YES                      YES


If you use compilation option 1 (compiling as modules) for lm_sensors, you
will have to make very sure the correct i2c header files are found. If you
get weird compilation errors, this is almost certainly going wrong. The
i2c header files are in a i2c subdirectory of either /usr/local/include 
(i2c compilation option 1) or /usr/src/linux*/include (i2c compilation
options 2 and 3). Especially if you have in the past placed the header
files in /usr/local/include, this will probably go wrong. See below on
how to fix this.


Having a proper kernel tree (compilation option 1)
==================================================

Usually, if you compile a user-space application, you can get away with
having a different version of the kernel running than the version of the
kernel header files against which you compiled it. But a perfect match
is needed for the first two compilation options above.

Let's say you want to use the lm_sensors modules with the kernel 2.1.12 you
are running now. What you need, is the original tree in which you
compiled that 2.1.12 kernel. A freshly unpacked 2.1.12 kernel will not
cut it, because `make *config dep' creates some files that are needed.
And even then, you will run into trouble, because you may not have
selected the exact same configuration variables. Plain advise: if you
do not have your original kernel tree anymore, recompile your kernel
first.

Note that there is no need for a perfect match at compilation time, just
at run-time. This means you can cross-compile against a different kernel
version, and the Makefile does not check for this.

Usually problems if the match is imperfect, is that either this package
won't compile at all (because it was a freshly unpacked tree without
some files generated by `make *config dep'), or that you can't insert
modules because of either a `kernel-module version mismatch' or because
of `unresolved kernel symbols'. If you get either of these messages,
check your kernel tree!

Note that some distributions are notably bad at this. To offset this
somewhat, not the files in /usr/include/{linux,asm} are used, but instead
those in /usr/src/linux/include/{linux,asm}. It is also possible to
tell the Makefile the kernel is somewhere else than at /usr/src/linux.


Separate from kernel compilation (compilation option 1)
=======================================================

This will compile and install the complete i2c package. Though nothing is
written to your kernel tree, a proper tree is still needed for this. See
earlier for what a proper kernel tree is.

At the top of the Makefile are a couple of configuration variables that
you may want to change. As far as possible, the Makefile tries to figure
out by itself their settings, but it is possible to overrule them. A list
is found below. Most important are the variables that determine where
your kernel is located (LINUX=/usr/src/linux), where the i2c header files
are (I2C_HEADERS=/usr/local/include) and where you want to install 
your modules (MODDIR=/lib/modules/KERNELVERSION/extra/misc) and
header files (LINUX_INCLUDE_DIR=/usr/local/include/linux). You can see
that the installation locations are choosen in such a way that they
are separate from the true kernel.

Compilation is done by `make all'; `make install' installs the package.
You will get a lot of warnings about files which are not found, all 
ending on `.*d'. You can safely ignore this; they contain dependency
information, which is regenerated on the spot.

Please continue reading this file before you start compiling.


Makefile configuration variables (compilation option 1)
==============================================================

SHELL (default: /bin/sh)
  You may have to specify the full path to Bash here, if /bin/sh is some
  other shell. There have been conflicting reports on whether this is 
  needed.
LINUX default: /usr/src/linux
  The location of your kernel tree.
COMPILE_KERNEL
  Determine whether you want to consider the kernel modules for compilation
  at all. By default, compilation option 1 will only compile and install
  those modules which are not built into the kernel.
  If some modules are built into your kernel, and this package is much 
  newer, you may find you can not insert the newly compiled modules. 
  Sorry.
  You may want to set this to 0 if you have just patched and compiled
  your kernel using the same version of this package, and just want to
  compile the user-space tools.
I2C_HEADERS default: /usr/local/include
  This lists where the i2c headers are found. If you used compilation
  option 1 for the i2c package, the default will be right. If you used
  compilation options 2 or 3, it will not, and may actually cause
  problems if you have the left-overs of a previous installation.
  If you have weird compilation problems, try to change this to
  $(LINUX_HEADERS).
SMP
  This must be set to 1 for a SMP kernel. The magic invocation should
  determine this automatically, so you should not have to bother with 
  this.
WARN default: 0
  Generate additional compilation warnings; mainly interesting for
  developers.
MODVER
  This must be set to 1 if CONFIG_MODVERSIONS is defined. The magic
  invocation should determine this automatically, so you should not
  have to bother with this.
DEBUG default: 0
  Some drivers will issue more debug information if you set this to
  1. Don't do it, unless you are a developer or are instructed to do
  so by the lm_sensors team.
PREFIX default: /usr/local
  Prefix for almost all installation directories
MODDIR default: /lib/modules/KERNELVERSION/extra/misc)
  The location where the kernel modules will be installed. 
ETCDIR default: /etc
  Installation location of the sensors.conf configuration file
LIBDIR default: $(PREFIX)/lib
  Installation location of all static and shared libraries.
BINDIR default: $(PREFIX)/bin
  Installation directory of programs useful for users
SBINDIR default: $(PREFIX)/sbin
  Installation directory of system administrator-only programs
INCLUDEDIR default: $(PREFIX)/include
  Base installation directory for include files (see next two vars)
SYSINCLUDEDIR default: $(INCLUDEDIR)/linux
  Installation directory for system include files
LIBINCLUDEDIR default: $(INCLUDEDIR)/sensors
  Installation directory for libsensors include files.
MANDIR default: $(PREFIX)/man
  Base installation directory for manual pages
MANOWN default: root
  Owner of manual pages
MANGRP default: root
  Group of manual pages



Handling the modules (compilation option 1)
===========================================

Once you have installed the kernel modules, you will have to make sure
they are found.

First, check whether your modutils will look in the right directory at
all. If you used build system 1, you will probably have to add lines
to /etc/conf.modules or /etc/modules.conf (use the one that exists, or
take your pick):
  (modules-2.0.0):
    path[misc]=/lib/modules/current/extra/misc
  (modutils-2.1.x):
    path=/lib/modules/current/extra
This assumes /lib/modules/current will always be linked to the correct
modules tree. If not, you will have to change it as appropriate for
your system.

Next, you will have to run `depmod -a' to have them recognised. Most
distributions run this command when you boot, so if you were cross-
compiling, you can skip this step.

See doc/modules for a more detailed treatment.


Patching the kernel (compilation option 2)
==========================================

There is a special script which should be able to generate diffs against
any 2.0, 2.1, 2.2 and 2.3 kernel. Please report any problems to our
mailinglist. Note that it may fail, and probably silently, if you have
applied other patches to your kernel tree, or for very new kernels.
It *is* safe to run it if your kernel already has the lm_sensors drivers.
It will only work if you applied the i2c patches first.

The kernel diffs are generated by the program `mkpatch.pl' in the mkpatch
subdirectory. It needs two arguments: the first one is the root of the
i2c package, the second one is the root of the kernel tree against
which the diffs will be generated. For example:
  cd /tmp/lm_sensors-2.4.0
  mkpatch/mkpatch.pl . /usr/src/linux > /tmp/sensors-patch
You can apply the diffs as usual:
  cd /usr/src/linux
  patch -p1 -E < /tmp/sensors-patch
Genearation and application can easily be done in one step:
  mkpatch/mkpatch.pl . /usr/src/linux | patch -p1 -E -d /usr/src/linux
The generated diffs are of course only valid for the kernel version 
against which mkpatch.pl was run.

Once you have applied the patches, you can configure and compile your
kernel as usual. You will see the sensors configuration screen under the
`Character Devices' menu in menuconfig, but it will only be available
if you selected base I2C support.


Using the sensors package
=========================

You can now load the modules by using `modprobe'. For example,
`modprobe i2c-piix4' will load the i2c-piix4 module, and all i2c modules
on which it depends.

You can not use demand-loading; you will have to issue explicit modprobe
instructions. 

If you have an older installation, you will probably have to create the
i2c device files in the /dev directory. They are called /dev/i2c-%d,
and are character devices with major device number 89 and minor device 
number %d. The script prog/mkdev/mkdev.sh will create the files for you.

There is a special scanning program installed called sensors-detect. It
will scan all available I2C and SMBus adapters for all known devices,
and give you a list of what modules you need to insert. It is written in
Perl, and you will need at least Perl 5.004 to run it succesfully.

You can use the installed sensors program to get a report of all detected
sensor devices. There is also a manual page for this program. Calling
`sensors -s' will set the limits and other configuration settings 
specified in /etc/sensors.conf. Again, read the manual pages for more
information.

There are many auxiliary programs not installed. You can find them under
the prog subdirectory. A list can be found in doc/progs.


Old and new I2C drivers
=======================

In the current 2.2 and 2.3 kernels, there are already I2C drivers, but
they are not the same ones as in this package. They are much older, and
have a very limited functionality compared with the drivers included
here. Fortunately, they can co-exist peacefully, so you should not worry
about it. Except for one thing: `#include <linux/i2c.h>' can cause the
wrong header file to be included. If you patched the kernel (compilation
option 3), you will have to use `#include <linux/i2c-old.h>' to include
the old ones; in all other cases, including the old ones will probably
be impossible without copying them explicitly to some place that will
be checked first.