Build vlastního balíčku OpenWRT

Balíčky hnízdí v package/ a dále následuje další dělení ale to je z pohledu buildu nepodstatné.
Například v package/utils/hello/src/ si vytvoříme klasický hello world balíček.

Do souboru hello.cpp vložíme toto:

#include <iostream>

using namespace std;

int main()
{
  cout << "Funguje to, mame prvni balicek pro OpenWRT!" << endl;

  return 0;
}

Dále musíme vytvořit Makefile s následujícím obsahem:

hello:hello.o

 $(CXX) $(LDFLAGS) hello.o -o hello

hello.o:hello.cpp

 $(CXX) $(CXXFLAGS) -c hello.cpp

# remove object files and executable when user executes "make clean"

clean:

 rm *.o hello 

Nyní je možné zkušebně si náš balíček přebuildit (ještě ne pro platformu OpenWRT):
make
g++  -c hello.cpp
g++  hello.o -o hello
A je tom máme binárku, kterou můžeme zatím spustit na našem buildícím stroji:
./hello
Funguje to, mame prvni balicek pro OpenWRT!

No ale naším cílem je udělat balíček pro OpenWRT, musíme tedy v package/utils/hello/ vytvořit dalším Makefile:

##############################################

# OpenWrt Makefile for helloworld program

#

#

# Most of the variables used here are defined in

# the include directives below. We just need to

# specify a basic description of the package,

# where to build our program, where to find

# the source files, and where to install the

# compiled program on the router.

#

# Be very careful of spacing in this file.

# Indents should be tabs, not spaces, and

# there should be no trailing whitespace in

# lines that are not commented.

#

##############################################

include $(TOPDIR)/rules.mk

# Name and release number of this package

PKG_NAME:=hello

PKG_RELEASE:=1

# This specifies the directory where we're going to build the program.

# The root build directory, $(BUILD_DIR), is by default the build_mipsel

# directory in your OpenWrt SDK directory

PKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)

include $(INCLUDE_DIR)/package.mk

# Specify package information for this program.

# The variables defined here should be self explanatory.

define Package/hello

 SECTION:=utils

 CATEGORY:=Utilities

 TITLE:=Testovací aplikace JFíla

 DEPENDS:=+libstdcpp

# DESCRIPTION:=\

# If you can't figure out what this program does, \\

# you're probably brain-dead and need immediate \\

# medical attention.

endef

define Package/hello/description

endef

# Specify what needs to be done to prepare for building the package.

# In our case, we need to copy the source files to the build directory.

# This is NOT the default.  The default uses the PKG_SOURCE_URL and the

# PKG_SOURCE which is not defined here to download the source from the web.

# In order to just build a simple program that we have just written, it is

# much easier to do it this way.

define Build/Prepare

 mkdir -p $(PKG_BUILD_DIR)

 $(CP) ./src/* $(PKG_BUILD_DIR)/

endef

# We do not need to define Build/Configure or Build/Compile directives

# The defaults are appropriate for compiling a simple program such as this one

# Specify where and how to install the program. Since we only have one file,

# the helloworld executable, install it by copying it to the /bin directory on

# the router. The $(1) variable represents the root directory on the router running

# OpenWrt. The $(INSTALL_DIR) variable contains a command to prepare the install

# directory if it does not already exist.  Likewise $(INSTALL_BIN) contains the

# command to copy the binary file from its current location (in our case the build

# directory) to the install directory.

define Package/hello/install

 $(INSTALL_DIR) $(1)/bin

 $(INSTALL_BIN) $(PKG_BUILD_DIR)/hello $(1)/bin/

endef

# This line executes the necessary commands to compile our program.

# The above define directives specify all the information needed, but this

# line calls BuildPackage which in turn actually uses this information to

# build a package.

$(eval $(call BuildPackage,hello))

No a nyní se vrátíme do hlavního adresáře SDK a spustíme konečně build pro WRTčko:
openwrt$ make package/hello/compile
 make[1] package/hello/compile
 make[2] -C package/libs/toolchain compile
 make[2] -C package/utils/hello compile

Jme šikulky, v /bin/<název_platformy>/packages/ máme archiv, to je náš první přeložený balíček packages/hello_1_<název_platformy>.ipk

Když se nezadaří, tak je dobré si překlad zopakovat s parametrem V=s pro kompletní výpis.