Infrastructure
==============

In order to facilitate learning each topic has a hands-on exercises
section which will contain in-depth, incremental clues on how to solve
one or multiple tasks. To focus on a particular issue most of the
tasks will be performed on existing skeleton drivers. Each skeleton
driver has clearly marked sections that needs to be filled in order to
complete the tasks.

The skeleton drivers are generated from full source examples located
in tools/labs/templates. To solve tasks you start by generating the
skeleton drivers, running the **skels** target in *tools/labs*. To
keep the workspace clean it is recommended to generate the skeletons
for one lab only and clean the workspace before start working on a new
lab. Labs can be selected by using the **LABS** variable:

.. code-block:: shell

   tools/labs $ make clean
   tools/labs $ LABS=kernel_modules make skels
		
   tools/labs $ ls skels/kernel_modules/
   1-2-test-mod  3-error-mod  4-multi-mod  5-oops-mod  6-cmd-mod  \
   7-list-proc  8-kprobes  9-kdb

You can also use the same variable to generate skeletons for specific
tasks:

.. code-block:: shell

   tools/labs $ LABS="kernel_modules/6-cmd-mod kernel_modules/8-kprobes" make skels
		
   tools/labs$ ls skels/kernel_modules
   6-cmd-mod  8-kprobes


For each task you may have multiple steps to perform, usually
incremental. These steps are marked in the source code as well as in
the lab exercises with the keyword *TODO*. If we have multiple steps
to perform they will be prefixed by a number, like *TODO1*, *TODO2*,
etc. If no number is used it is assumed to be the one and only
step. If you want to resume a task from a certain step, you can using
the **TODO** variable. The following example will generate the
skeleton with the first *TODO* step resolved:

.. code-block:: shell

   tools/labs $ TODO=2 LABS="kernel_modules/8-kprobes" skels

Once the skelton drivers are generated you can build them with the
**build** make target:

.. code-block:: shell

   tools/labs $ make build
   echo "# autogenerated, do not edit " > skels/Kbuild
   for i in ./kernel_modules/8-kprobes; do echo "obj-m += $i/" >> skels/Kbuild; done
   make -C /home/tavi/src/linux M=/home/tavi/src/linux/tools/labs/skels ARCH=x86 modules
   make[1]: Entering directory '/home/tavi/src/linux'
   CC [M]  /home/tavi/src/linux/tools/labs/skels/./kernel_modules/8-kprobes/kprobes.o
   Building modules, stage 2.
   MODPOST 1 modules
   CC      /home/tavi/src/linux/tools/labs/skels/./kernel_modules/8-kprobes/kprobes.mod.o
   LD [M]  /home/tavi/src/linux/tools/labs/skels/./kernel_modules/8-kprobes/kprobes.ko
   make[1]: Leaving directory '/home/tavi/src/linux'


To copy the drivers to the VM you can use either use ssh or update the
VM image directly using the **copy** target:

.. code-block:: shell

   tools/labs $ make copy
   ...
   'skels/kernel_modules/8-kprobes/kprobes.ko' -> '/tmp/tmp.4UMKcISmQM/home/root/skels/kernel_modules/8-kprobes/kprobes.ko'

.. attention:: The **copy** target will fail if the VM is
   running. This is intentional so that we avoid corrupting the
   filesystem.