
                      =============================
                      How to start exploring Genode
                      =============================

                               Norman Feske


Abstract
########

This guide is meant to provide you a painless start with using the Genode OS
Framework. It explains the steps needed to get a simple demo system running
on Linux first, followed by the instructions on how to run the same scenario
on a microkernel.


Quick start to build Genode for Linux
#####################################

The best starting point for exploring Genode is to run it on Linux. Make sure
that your system satisfies the following requirements:

* GNU 'Make' version 3.81 or newer
* 'libSDL-dev'
* 'tclsh' and 'expect'
* 'byacc' (only needed for the L4/Fiasco kernel)
* 'qemu' and 'genisoimage' (for testing non-Linux platforms via Qemu)

Furthermore, you will need to install the official Genode toolchain, which
you can download at [http://genode.org/download/tool-chain].

The Genode build system never touches the source tree but generates object
files, libraries, and programs in a dedicated build directory. We do not have a
build directory yet. For a quick start, let us create one for the Linux base
platform:

! cd <genode-dir>
! ./tool/create_builddir linux_x86 BUILD_DIR=build.lx

The new build directory is called 'build.lx' and configured for the 'linux_x86'
platform. To give Genode a try, build and execute a simple demo scenario via:

! cd build.lx
! make run/demo

By invoking 'make' with the 'run/demo' argument, all components needed by the
demo scenario are built and the demo is executed. If you are interested in
looking behind the scenes of the demo scenario, please refer to
'doc/build_system.txt' and the run script at 'os/run/demo.run'.


Using platforms other than Linux
================================

Running Genode on Linux is the most convenient way to get acquainted with the
framework. However, the point where Genode starts to shine is when used as the
user land executed on a microkernel. The framework supports a variety of
different kernels such as L4/Fiasco, L4ka::Pistachio, OKL4, and NOVA. Those
kernels largely differ in terms of feature sets, build systems, tools, and boot
concepts. To relieve you from dealing with those peculiarities, Genode provides
you with an unified way of using them. For each kernel platform, there exists
a dedicated directory called 'base-<platform>'. Within this directory, you will
find a 'Makefile', which automates the task of downloading the source codes of
the kernel and interfacing the kernel with Genode. Just change to the
respective 'base-<platform>' directory and issue:

! make prepare

Note that each 'base-<platform>' directory comes with a 'README' file, which
you should revisit first when exploring the base platform. Additionally, most
'base-<platform>' directories provide more in-depth information within their
respective 'doc/' subdirectories.

For the VESA driver on x86, the x86emu library is required and can be
downloaded and prepared by invoking the following command from within the
'libports' directory:

! make prepare PKG=x86emu

Now that the base platform is prepared, the 'create_builddir' tool can be used
to create a build directory for your platform of choice by giving the platform
as argument. To see the list of available platforms, execute 'create_builddir'
with no arguments.

For example, to give the demo scenario a spin on the OKL4 kernel, the following
steps are required:

# Download the kernel:
  ! cd <genode-dir>
  ! make -C base-okl4 prepare
# Create a build directory
  ! ./tool/create_builddir okl4_x86 BUILD_DIR=build.okl4
# Uncomment the following line in 'build.okl4/etc/build.conf'
  ! REPOSITORIES += $(GENODE_DIR)/libports
# Build and execute the demo using Qemu
  ! make -C build.okl4 run/demo

The procedure works analogously for the other base platforms.


How to proceed with exploring Genode
####################################

Now that you have taken the first steps into using Genode, you may seek to
get more in-depth knowledge and practical experience. The foundation for doing
so is a basic understanding of the build system. The documentation at
'build_system.txt' provides you with the information about the layout of the
source tree, how new components are integrated, and how complete system
scenarios can be expressed. Equipped with this knowledge, it is time to get
hands-on experience with creating custom Genode components. A good start is the
'hello_tutorial', which shows you how to implement a simple client-server
scenario. To compose complex scenarios out of many small components, the
documentation of the Genode's configuration concept at 'os/doc/init.txt' is an
essential reference.

Certainly, you will have further questions on your way with exploring Genode.
The best place to get these questions answered is the Genode mailing list.
Please feel welcome to ask your questions and to join the discussions:

:Genode Mailing Lists:

  [http://genode.org/community/mailing-lists]

