modules

I2C总线LINUX驱动程序

Managing Modules
================

The hardcore way is to insmod each of them by hand. This is not very
practical, though. It is better to install them in a subdirectory that
modprobe examines. /lib/modules/current/extra/misc comes to mind.
You need to add this path to your /etc/modules.conf (or /etc/conf.modules,
which file is used depends on your distribution):
  (modules-2.0.0):
    path[misc]=/lib/modules/current/extra/misc
  (modutils-2.1.x):
    path=/lib/modules/current/extra
Do always a 'depmod -a' after changing either your configuration file or 
changing a module in one of the module directories; you also need to do
a 'killall -HUP kerneld' if you still use kerneld (kernel 2.2.x usually
uses kmod).

Now you can do 'modprobe i2c-elv', and all dependent modules are loaded
automatically. You could, of course, add this statement (and related
statements for other drivers) somewhere in your rc files. But, most
distributions are set up to load automatically all files in the
'boot' directories on system start, so why not use this? The best
way to do this is to create directory /lib/modules/boot, and to
put *links* to the real modules in there. Why links? Well, by linking
to /lib/modules/current/whatever, this will function for any kernel
(provided /lib/modules/current is correctly set up to point to the
current kernel). So:
  mkdir -p /lib/modules/boot
  ln -s ../current/extra/misc/lm78.o /lib/modules/boot/i2c-elv.o
  # etc.

It is also possible to specify default options, that you would normally
enter at the insmod command, in the configuration file. The syntax is
as follows:
  options i2c-core debug=2

Finally, it is possible to auto-load the i2c-dev module if a /dev/i2c-*
file is accessed. You need the following line in the configuration file:
  alias char-major-89 i2c-dev

With the above, the managing of all those modules is suddenly no problem
at all!