Building RTEMS and its example for sparc architecture

The purpose of this work is to show how to easily get started with RTEMS real-time operating system. In the article I will show how to compile RTEMS, compile 'Hello World' application and run it in a simulator. The example and RTEMS system itself will be compiled for sparc/erc32 architecture and will be launched in the simulator. More information about RTEMS you can find on the official site: rtems.org.

Building the kernel.

First of all, we should create a directory for our project. I have my own directory for projects, so I will create a new project in it:

cd ~/Projects #my directory for projects
$ mkdir ./development/rtems/kernel
$ cd ./development/rtems/kernel

At this stage we can create an alias for our development folder:

$ export RTEMS_DEV=$HOME/Projects/development

Now, we should obtain RTEMS distro from its git repository:

$ git clone git://git.rtems.org/rtems.git

Next step, we should install the tools. We need to do it, because we should compile rtems for our target system, thus, we need a cross-compiler. And cross-compiler itself is built by the build system - RSB. Let's create a directory for it:

$ mkdir ./rtems/rsb
$ cd ./rtems/rsb

then, download and install it:

$ git clone git://git.rtems.org/rtems-source-builder.git
$ cd rtems-source-builder
$ cd rtems
$ ../source-builder/sb-set-builder --prefix=$RTEMS_DEV/rtems/4.12 4.12/rtems-sparc

Let's build RTEMS itself. First of all, we should do a bootstrapping:

$ cd ./../../../kernel/rtems
$ ./bootstrap -c && ./bootstrap -p && $RTEMS_DEV/rtems/rsb/rtems-source-builder/source-builder/sb-bootstrap

After that, RTEMS kernel should be configured:

$ cd ../
$ mkdir erc32
$ cd erc32/
$ RTEMS_DEV/rtems/kernel/rtems/configure --prefix=$RTEMS_DEV/rtems/4.12 --target=sparc-rtems4.12 --enable-rtemsbsp=erc32 --enable-posix

and build:

$ make -j8

and installed:

$ make install

At this point we should have a built RTEMS kernel. Let's examine our results. There are three main directories:

$RTEMS_DEV/rtems/4.12/bin/ - it consists of built tools, such as compiler, debugger and so on.

$RTEMS_DEV/rtems/kernel/erc32/sparc-rtems4.12/erc32/lib/include/ - in this directory header files are placed.

$RTEMS_DEV/rtems/kernel/erc32/sparc-rtems4.12/erc32/lib/ - in this folder there are different object files, like libbsp object file and libchip file.

Building examples.

First of all, we should download examples from RTEMS git repository into our $RTEMS_DEV folder:

$ git clone git://git.rtems.org/examples-v2.git
$ cd exampes-v2

Let's follow the instructions in README.waf file:

$ git submodule init
$ git submodule update

Now we have obtained new folder rtems_waf, which contains some scripts which support application building with waf build system.


Before building our example application we should build rtems-tools:

$ cd $RTEMS_DEV/rtems

$ git clone git://git.rtems.org/rtems-tools.git

$ cd ./rtems-tools
$ ./waf configure --prefix=$RTEMS_DEV/rtems/4.12
$ ./waf build install

As a prefix we can use another location.

Let's now build examples themselves:

$ cd ../examples-v2

If you don't have yet a path to your compiler and debugger in your PATH variable (you can check it with command 'echo $PATH'):

$ export PATH=$RTEMS_DEV/rtems/4.12/bin:$PATH

Now, we should configure our examples:

$ cp $RTEMS_DEV/rtems/rtems-tools/waf ./
$ chmod u+x ./waf
$ ./waf configure --rtems=$RTEMS_DEV/rtems/4.12 \
                          --rtems-tools=$RTEMS_DEV/rtems/4.12 \
                          --rtems-bsps=sparc/erc32 \
                          --rtems-version=4.12
$ ./waf

At the moment of this article writing, the building process was failing. So, let's compile a distinct example:

$ cd hello/posix_hello_world/
$ ../../waf
$ cd ../../build/sparc-rtems4.12-erc32/hello/posix_hello_world/
$ sparc-rtems4.12-run posix_hello.exe

The output should be:

*** HELLO WORLD TEST ***

Hello World

*** END OF HELLO WORLD TEST ***

It seems, that our first application works!