Building Existing Software Packages with EMAC OE SDK

TODO: {{#todo: update this with our own mirror locations; add missing summary for oe 4; add CMake info for OE 5|Michael Gloff|oe 4,mg,ky,Review}}

It is often necessary to build an existing project from source code. This is the case when a specific program is required to run on the target device and pre-compiled binaries do not exist. In the steps below, the EMAC SDK toolchain will be used to compile an existing Makefile based project and an Autotools based project that can be run on the target device.

Makefile-based Projects

The GNU make utility uses one or more Makefiles to direct the compiler to what source files to build and what options to use when building. Makefile based projects are generally set up for larger complex projects to simplify the configuration of the project. The example below uses a relatively simple project that can be extended as needed.

HelloMake Project Example

The HelloMake project contains two source files, a header file, and a Makefile. The Makefile will direct make to use the correct target compiler and libraries to compile the source and header files into an executable. The header file is located in the include directory as is common with larger projects. The obj files created will be stored in the obj directory to keep from cluttering the source directory and the executable will be placed in the bin directory. The Makefile also contains a clean target to remove all of the temporary and intermediate files and an upload target to upload the executable to the target device.

1. Begin by downloading the HelloMake project

2. Extract the project.

   developer@ldc:~$ tar zxvf HelloMake.tar.gz
   

3. Modify the first line of Makefile in the src directory to point to the path to the correct global.properties file. Make sure that the setmachine script has been run before attempting to build the project. This allows make to use the correct compiler and compile options for the target machine.

   include /path/to/sdk/projects/global.properties
   

4. From the command prompt in the src directory type make

   developer@EMAC-LDC-32bit:~/EMAC-OE-arm-linux-gnueabi-SDK_4.0/HelloMake/src$ make
   
   ../../gcc-4.3.1-arm-emac-linux-gnueabi/bin/arm-emac-linux-gnueabi-gcc  -MMD -g -march=armv7-a -mtune=cortex-a8 -mfpu=neon -c -o obj/hellomake.o hellomake.c
   ../../gcc-4.3.1-arm-emac-linux-gnueabi/bin/arm-emac-linux-gnueabi-gcc  -MMD -g -march=armv7-a -mtune=cortex-a8 -mfpu=neon -c -o obj/hellofunc.o hellofunc.c
   ../../gcc-4.3.1-arm-emac-linux-gnueabi/bin/arm-emac-linux-gnueabi-gcc   -lm -o ../bin/hellomake obj/hellomake.o obj/hellofunc.o
   

5. After successfully compiling the project, the upload make target can be used to transfer the executable to the target machine as specified by the upload line in Makefile.

   developer@ldc:~$ make upload
   

   
   

Autotools-based Projects

The GNU build system is known as Autotools. Autotools is a group of applications that are designed to provide a configurable build system to allow compilation on different platforms and environments. A configure script and set of input files are used to generate makefiles based on options passed to the configure script and deduced from the system environment. This includes tests for compiler options, library functions, install configuration, and other assorted variables.

The configure script is the most important step in building an autotools-based project. Although available options for configure vary depending on the project design, there are common options shared between most autotools projects.

libConfuse Example Project

The libConfuse project is a simple C library written for parsing configuration files. It uses an autotools build system for configuration. The steps below demonstrate how to build libConfuse and should be used as an example for building other autotools-based projects.

1. The source code for the libConfuse project can be downloaded as described on the project website. For this example, release 2.7 is used. After downloading the source, extract the archive and navigate to the top-level directory of the project.

2. Read through the README and INSTALL files for information on the project and general information on how to build it. Also, look at the help output from configure to see a summary of the available options:

   developer@ldc:~$ ./configure --help
   

3. In order for autotools to use the correct compiler and compile options, the CFLAGS, CC, and CXX variables need to be set. Open the correct global.properties file to see what the values should be. The example below is for an armv5 processor.

   developer@ldc:~$ export CC="/path/to/sdk/gcc-4.2.4-arm-linux-gnueabi/bin/arm-linux-gnueabi-gcc"
   developer@ldc:~$ export CXX="/path/to/sdk/gcc-4.2.4-arm-linux-gnueabi/bin/arm-linux-gnueabi-g++"
   developer@ldc:~$ export CFLAGS="-O2 -march=armv5te -mtune=arm926ej-s"
   developer@ldc:~$ export DESTDIR=`pwd`/Install
   

4. After setting the environment, configure can be run with the appropriate options to configure the build system and generate the makefiles. The code below shows an example configuration. Be sure to set the host and target correctly based on the architecture:

   developer@ldc:~$ ./configure --build=i686-linux --host=arm-linux-gnueabi --target=arm-linux-gnueabi \
           --prefix=/usr --exec_prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin \
           --datadir=/usr/share  \
           --infodir=/usr/share/info \
           --mandir=/usr/share/man --enable-shared
   

   The configuration should complete successfully. If any problems are reported that result in an error, check the environment settings and configure options again.

5. Now that configure has generated all of the makefiles for the project, make can be used to compile the source code:

   developer@ldc:~$ make all
   

   If any errors are encountered during compilation, examine the output of configure and make sure that all of the environment variables and configure options were specified correctly.

6. Once compilation is complete, the install target can be used to package all of the necessary files together so that they can be transferred to the target board.

   developer@ldc:~$ make install
   developer@ldc:~$ ls -R Install
   

   Install:
   usr
   
   Install/usr:
   include  lib  share
   
   Install/usr/include:
   confuse.h
   
   Install/usr/lib:
   libconfuse.a  libconfuse.la  libconfuse.so  libconfuse.so.0  libconfuse.so.0.0.0  pkgconfig
   
   Install/usr/lib/pkgconfig:
   libconfuse.pc
   
   Install/usr/share:
   locale
   
   Install/usr/share/locale:
   fr  sv
   
   Install/usr/share/locale/fr:
   LC_MESSAGES
   
   Install/usr/share/locale/fr/LC_MESSAGES:
   confuse.mo
   
   Install/usr/share/locale/sv:
   LC_MESSAGES
   
   Install/usr/share/locale/sv/LC_MESSAGES:
   confuse.mo
   

   
   

See Also

GNU make documentation.

Autotools documentation.