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slackbook:linux_kernel [2012/09/17 03:34 (UTC)]
mfillpot Moved text to the proper section
slackbook:linux_kernel [2012/09/17 03:35 (UTC)]
mfillpot [Working with Modules] Aded original text and formatting
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 ===== Working with Modules ===== ===== Working with Modules =====
 +The complexity of a modern linux kernel is staggering. The source code
 +for the kernel weighs in at nearly 400MB uncompressed. There are
 +thousands of developers, hundreds of options, and if everything were
 +built together, the kernel would soon pass 100MB in size itself. In
 +order to keep the size of the kernel down (as well as the amount of RAM
 +needed for the kernel), most of the kernel options are built as
 +modules. You can think of these modules as device drivers which can be
 +inserted or removed from a running kernel at will. In truth, many of
 +them aren't device drivers at all, but contain support for things such
 +as network protocols, security measures, and even filesystems. In
 +short, nearly any piece of the linux kernel can be built as a loadable
 +It's important to realize that Slackware will automatically handle
 +loading most modules for you. When your system boots,
 +**//​udevd//​**(8) is started and begins to probe your
 +system'​s hardware. For each device it finds, it loads the proper module
 +and created a device node in ''/​dev''​. This usually
 +means that you will not need to load any modules in order to use your
 +computer, but occasionally this is necessary.
 +So what modules are currently loaded on your computer and how do we
 +load and unload them? Fortunately we have a full suite of tools for
 +handling this. As you might have guessed, the tool for listing modules
 +is **//​lsmod//​**(8).
 +darkstar:~# lsmod
 +Module ​                 Size  Used by
 +nls_utf8 ​               1952  1 
 +cifs                  240600 ​ 2 
 +i915                  168584 ​ 2 
 +drm                   ​168128 ​ 3 i915
 +i2c_algo_bit ​           6468  1 i915
 +tun                    12740  1 
 +... many more lines ommitted ...
 +In addition to showing you what modules are loaded, it displays the
 +size of each module and tells you what other modules are using it.
 +There are two applications for loading modules:
 +**//​insmod//​**(8) and
 +**//​modprobe//​**(8). Both will load modules and
 +report any errors (such as loading a module for a device that isn't
 +present in your system), but **//​modprobe//​** is
 +preferred because it can load any module dependencies. Using either is
 +darkstar:~# insmod ext3
 +darkstar:~# modprobe ext4
 +darkstar:~# lsmod | grep ext
 +ext4                  239928 ​ 1 
 +jbd2                   ​59088 ​ 1 ext4
 +crc16                   ​1984 ​ 1 ext4
 +ext3                  139408 ​ 0 
 +jbd                    48520  1 ext3
 +mbcache ​                ​8068 ​ 2 ext4,ext3
 +Removing modules can be a tricky process, and once again we have two
 +programs for removing them: **//​rmmod//​**(8) and
 +**//​modprobe//​**. ​ In order to remove a module with
 +modprobe, you'll need to use the //-r// argument.
 +darkstar:~# rmmod ext3
 +darkstar:~# modprobe -r ext4
 +darkstar:~# lsmod | grep ext
 ===== Compiling A Kernel and Why to do So ===== ===== Compiling A Kernel and Why to do So =====

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