Wiki:help/howtos/development/developer_information/package_development_start

First steps - How to start your first freetz package

Info

In this howto you will find a number of examples for building packages, each with their own parameters.
The first part will describe the build environment, and preparing the Toolchain.
Than the first example package is the HTTP tunnel server. This package is an easy to compile, and a good choice for your first freetz package. Httptunnel is already included in freetz nowadays.

The second example will show the package par2cmdline. Par2cmdline doesn’t require much additional parameters, but does require a patch. This package require a lot of CPU and memory resources so that makes this package less interesting for inclusion into Freetz.

The third example is for package nzbget. NZBget needs a few additional parameters, a small patch, and a library that is already part of Freetz. Also this package requires a lot of CPU and memory resources, and maybe only useful on the most powerful FritzBox models.

Build Environment

There are different platforms which you may use to build your package, but usually all involve Linux in some way. Currently Freetz-Linux looks to be the most updated choice.

Just use the latest freetz-linux availble. I used:

freetz-linux 1.2.1 (with xz added with: sudo apt-get install xz-utils)
(from revision 11347 the following is needed: sudo apt-get install libacl1-dev libattr1-dev libcap-dev)
(from revision ??? the following is also needed: sudo apt-get install imagemagick)

Very helpful information on make-targets such as menuconfig, toolchain, precompiled, recover etc. may be retrieved in the HowTos section of the Freetz wiki.

Toolchain

The toolchain is built automatically with "make" (see below).

If you want to have your toolchain ready at an earlier stage, you can create it now:
Go to your build environment and change to your freetz directory, usually ~/freetz-trunk.

In make menuconfig, select your hardware type (e.g. 7170), and after setting the Level of user competence to Expert you can look around in 'Toolchain options', but no changes are normally needed.

$ make menuconfig
       Level of user competence (Expert)  --->
       Hardware type (7170)  --->
       Firmware language (en - international)  --->
       Toolchain options  --->
                 No changes needed

Then create your toolchain:

$ make toolchain

(for older revisions:)
FINISHED: toolchain/kernel/ - glibc compiler for the kernel
          toolchain/target/ - uClibc compiler for the userspace
(for later revisions:)
FINISHED: new download toolchains can be found in dl/

In order to build your new package manually (without integration in the freetz build system), you should see that your toolchain is also included in the search path.

File Structure

Below the file structure used in the build environment (cross-compile environment) e.g. Freetz-linux mentioned earlier.

Font Green = executable
Font Blue = directory

The following files are required for compiling the package, e.g. for entries in make menuconfig and cross-compile steps.
The patches are optional, and only needed if the downloadable source needs some changes.

make/<package>/Config.in
make/<package>/patches/*
make/<package>/<package>.mk

The following group of files are applicable if you plan to build a web-interface.
The <package>.cfg contains the default configuration parameters.
The <package>_conf is an optional script for generating a config file if the deamon (binary) needs it.
The rc.<package> is responsible to start/stop the deamon with the proper parameters, and having the package included in the menu of the web-interface.
The <package>.cgi is used to create the body of the web-interface, where you can find the more HTML like statements.
The .language is used to translate the <package>.cgi web-interface to the selected language. The file should highlight the files with lang statements, to translate/select the target language.
The directory usr/lib/cgi-bin/<package>/ is used for optional extra cgi scripts.

make/files/root/etc/default.<package>/<package>.cfg
make/files/root/etc/default.<package>/<package>_conf
make/files/root/etc/default.<package>/<package>.save
make/files/root/etc/init.d/rc.<package>
make/files/root/usr/lib/cgi-bin/<package>.cgi
make/files/root/usr/lib/cgi-bin/<package>/*

Examples Binary Package

Configuration Handling

The configuration is saved in the non-volatile memory (tffs) via a character device /var/flash/freetz/.
This is done by saving (writing) a tar file containing all config data to this character device.
You can test this with:

cat /var/flash/freetz > /var/tmp/config.tar
tar tf /var/tmp/config.tar

Freetz has a number of tools for handling configuration data and ‘saving them to’ / ’reading them from’ tffs.
The data from the character device is taken-from / saved-to /var/tmp/flash.
/tmp is a symbolic-link (symlink) to /var/tmp, so this makes /tmp/flash/ is the same as /var/tmp/flash

# ls -al /tmp
lrwxrwxrwx 1 root root 7 Jan 12 01:56 /tmp -> var/tmp

/tmp/flash is the location where all configuration data is gathered. A look into this directory should let you recognize the files also seen with the previous tar tf command.
The default configuration file (e.g. the file you need to create for the package) is located at /mod/etc/default.<package>/<package>.cfg.
This is a static file containing a pre-defined value (can be empty) for each variable (config parameter) in the following format:

export <PACKAGE>_<VARIABLE1>=’<value1>’
export <PACKAGE>_<VARIABLE2>=’<value2>’
export <PACKAGE>_<VARIABLE3>=’<value3>’
.
.
.
export < PACKAGE>_<VARIABLEn>=’<valuen>’

These are also the values that will be used if you revert back to the default parameters via the web-interface using the ‘default’ button.
This config file is using Shell syntax which makes it possible to use the file as command lines.

After changes are made via the web-interface, and saved with the ‘Apply’ button they are written to /mod/etc/conf/<package>.cfg
This file contains all the variables, so some changed, others still default, depending on the changes made (so the actual config values).
So the file /mod/etc/conf/<package>.cfg containing the actual values, and /mod/etc/default.<package>/<package>.cfg with the default values contain the same parameters, but not necessarily in the same order.
Again using the Shell syntax and the variables can be exported using: . /mod/etc/conf/<package>.cfg

To preserve space in the non-volatile memory (tffs) only the difference with the default parameters (/mod/etc/default.<package>/<package>.cfg) and the actual changed parameters (/mod/etc/conf/<package>.cfg) are saved to /tmp/flash. This can be seen from the ‘.diff’ extension e.g. /tmp/flash/<package>.diff.

The main package for controlling all package config is mod. Mod contains a number of tools for handling package config:

modconf load <package>
modconf save <package>
modsave
modsave flash

Create the data /mod/etc/conf/<package>.cfg from the default conf file /mod/etc/default.<package>/<package>.cfg and /tmp/flash/<package>.diff
Create the data /tmp/flash/<package>.diff from the default conf file /mod/etc/default.<package>/<package>.cfg and /mod/etc/conf/<package>.cfg
Initiate for each package 'modconf save' and saves the results located in ‘/tmp/flash’ to tffs (non-volatile memory)
Saves the content of ‘/tmp/flash/’ to tffs (non-volatile memory)

Examples explaining these commands.

Examples Web-Interface

Example 1 - httptunnel

Trouble shooting

If you see during make or make menuconfig only dots appear you probably started creating a new package stucture, which is still unfinished.
Just remove the unfinshed directory.

A failure like checking whether the C compiler (mipsel-linux-gcc -O2 -Wall -fomit-frame-pointer ) works… no
configure: error: installation or configuration problem: C compiler cannot create executables. most likely point to a wrong PATH environment setting.
Use echo $PATH for trouble shooting.
This can be expected if you first manually compiled the package, and than add the package to Freetz and try to create an image, with the previous exports still present.
A reboot might be the savest option.