openadk/docs/using.txt

// -*- mode:doc; -*-
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Using OpenADK
-------------

OpenADK has a nice configuration tool similar to the one you can
find in the http://www.kernel.org/[Linux kernel] or in
http://www.busybox.net/[Busybox]. Note that you can *and should build
everything as a normal user*. There is no need to be root to configure
and use OpenADK. The first step is to run the configuration
assistant:

--------------------
 $ make menuconfig
--------------------

For each menu entry in the configuration tool, you can find associated
help that describes the purpose of the entry.

image::openadk-menu.png[]

First of all you need to choose if you want to build a Linux firmware
or a bare-metal toolchain. Linux is choosen as default.

image::openadk-arch.png[]

After that you should select your target architecture.

image::openadk-system.png[]

Now you can select your target system, endianess, cpu and other stuff.

image::openadk-task.png[]

If you want to compile some predefined appliance tasks, you can select it in +Tasks+.
You can later simply add your own tasks, which is a collection of options, packages,
kernel modules or features, runtime configuration and more. They can either be placed
inside the +tasks+ directory or in your own custom directory that you pass via
+ADK_CUSTOM_TASKS_DIR+ to make.

When you are ready exit and save. You can always redefine the
configuration using +make menuconfig+.

Once everything is configured, the configuration tool generates a
+.config+ file that contains the description of your configuration. It
will be used by the Makefiles to do what's needed.

Let's go:

--------------------
 $ make
--------------------

You *should never* use +make -jN+ with OpenADK: it does not support 'top-level
parallel make'. Instead, use the +ADK_MAKE_JOBS+ option in +Global settings+ to
tell OpenADK to run each package compilation with +make -jN+.

The `make` command will generally perform the following steps:

* download source files
* configure, build and install required host tools
* configure, build and install the cross-compiling toolchain
* build a kernel image, if selected
* build/install selected target packages
* build a bootloader, if selected
* create a root filesystem in selected format

OpenADK output is stored in several subdirectories: 

* +firmware/+ where all the images and packages are stored.

* +build_<system>_<libc>_<arch>_<abi>/+ where all the components except for the
  cross-compilation toolchain are built. The directory contains one
  subdirectory for each of these components.

* +target_<system>_<libc>_<arch>_<abi>/+ which contains a hierarchy similar to a root filesystem
  hierarchy. This directory contains the installation of the
  cross-compilation toolchain and all the userspace packages selected
  for the target. However, this directory is 'not' intended to be
  the root filesystem for the target: it contains a lot of development
  files, unstripped binaries and libraries that make it far too big
  for an embedded system. These development files are used to compile
  libraries and applications for the target that depend on other
  libraries.

* +root_<system>_<libc>_<arch>_<abi>/+ which contains the complete root filesystem for
  the target. One exception, it doesn't have the correct
  permissions (e.g. setuid for the busybox binary) for some files. 
  Therefore, this directory *should not be used on your target*.  
  Instead, you should use one of the images or archives built in the 
  +firmware/+ directory. If you need an
  extracted image of the root filesystem for booting over NFS, then
  use the tarball image generated in +firmware/+ and extract it as
  root. Compared to +build_*/+, +target_*/+ contains only the files and
  libraries needed to run the selected target applications: the
  development files are (exception: if any dev packages are selected)
  not present, the binaries are stripped.

* +host_<gnu_host_name>/+ contains the installation of tools compiled for the host
  that are needed for the proper execution of OpenADK

* +host_build_<gnu_host_name>/+ contains the build directories of tools compiled for the host
  that are needed for the proper execution of OpenADK

* +toolchain_<system>_<libc>_<arch>_<abi>>/+ contains just the cross-compilation toolchain.
  Can be used together with +target_<system>_<libc>_<arch>_<abi>/+ for other projects. Toolchain
  is relocatable.

* +toolchain_build_<system>_<libc>_<arch>_<abi>/+ contains the build directories for the various
  components of the cross-compilation toolchain.

* +pkg_<system>_<libc>_<arch>_<abi>/+ contains stamp files and file lists for the various components.

The command, +make menuconfig+ and +make+, are the
basic ones that allow to easily and quickly generate images fitting
your needs, with all the applications you enabled.

More details about the "make" command usage are given in
xref:make-tips[].