2.7. Build Your Application

You tested a BSP in the previous section. We built the erc32 BSP and it is installed under $HOME/quick-start/rtems/5.

We will now create a simple Hello World application with a Git repository and using the Waf build system.

The application is be created in $HOME/quick-start/app/hello.

In the output in this section the base directory $HOME/quick-start was replaced by $BASE.

The steps in this section assume you are in the directory $HOME/quick-start/app/hello after the first step changes to it.

Setup the application work space. Create a new Git repository, download the Waf build system, and the RTEMS Waf.

Create the application directory and change into it:

mkdir -p $HOME/quick-start/app/hello
cd $HOME/quick-start/app/hello

Download the Waf build system and set it to executable:

curl https://waf.io/waf-2.0.19 > waf
chmod +x waf

Initialise a new Git repository:

git init

Add RTEMS Waf support as a Git sub-module and initialise it:

git submodule add git://git.rtems.org/rtems_waf.git rtems_waf

Create the application source files. Three files are created with an editor of your choice.

First create a C file that configures RTEMS. Using an editor create a file called init.c and copy the following configuration settings:

/*
 * Simple RTEMS configuration
 */

#define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
#define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER

#define CONFIGURE_UNLIMITED_OBJECTS
#define CONFIGURE_UNIFIED_WORK_AREAS

#define CONFIGURE_RTEMS_INIT_TASKS_TABLE

#define CONFIGURE_INIT

#include <rtems/confdefs.h>

Create the Hello World application source file. Using an editor create hello.c and copy the follow code:

/*
 * Hello world example
 */
#include <rtems.h>
#include <stdlib.h>
#include <stdio.h>

rtems_task Init(
  rtems_task_argument ignored
)
{
  printf( "\nHello World\n" );
  exit( 0 );
}

Finally create the Waf script. Using an editor create wscript and copy the Waf script:

#
# Hello world Waf script
#
from __future__ import print_function

rtems_version = "5"

try:
    import rtems_waf.rtems as rtems
except:
    print('error: no rtems_waf git submodule')
    import sys
    sys.exit(1)

def init(ctx):
    rtems.init(ctx, version = rtems_version, long_commands = True)

def bsp_configure(conf, arch_bsp):
    # Add BSP specific configuration checks
    pass

def options(opt):
    rtems.options(opt)

def configure(conf):
    rtems.configure(conf, bsp_configure = bsp_configure)

def build(bld):
    rtems.build(bld)

    bld(features = 'c cprogram',
        target = 'hello.exe',
        cflags = '-g -O2',
        source = ['hello.c',
                  'init.c'])

Configure the application using Waf’s configure command:

./waf configure --rtems=$HOME/quick-start/rtems/5 --rtems-bsp=sparc/erc32

The output will be something close to:

Setting top to                           : $BASE/app/hello
Setting out to                           : $BASE/app/hello/build
RTEMS Version                            : 5
Architectures                            : sparc-rtems5
Board Support Package (BSP)              : sparc-rtems5-erc32
Show commands                            : no
Long commands                            : no
Checking for program 'sparc-rtems5-gcc'  : $BASE/rtems/5/bin/sparc-rtems5-gcc
Checking for program 'sparc-rtems5-g++'  : $BASE/rtems/5/bin/sparc-rtems5-g++
Checking for program 'sparc-rtems5-gcc'  : $BASE/rtems/5/bin/sparc-rtems5-gcc
Checking for program 'sparc-rtems5-ld'   : $BASE/rtems/5/bin/sparc-rtems5-ld
Checking for program 'sparc-rtems5-ar'   : $BASE/rtems/5/bin/sparc-rtems5-ar
Checking for program 'sparc-rtems5-nm'   : $BASE/rtems/5/bin/sparc-rtems5-nm
Checking for program 'sparc-rtems5-objdump' : $BASE/rtems/5/bin/sparc-rtems5-objdump
Checking for program 'sparc-rtems5-objcopy' : $BASE/rtems/5/bin/sparc-rtems5-objcopy
Checking for program 'sparc-rtems5-readelf' : $BASE/rtems/5/bin/sparc-rtems5-readelf
Checking for program 'sparc-rtems5-strip'   : $BASE/rtems/5/bin/sparc-rtems5-strip
Checking for program 'sparc-rtems5-ranlib'  : $BASE/rtems/5/bin/sparc-rtems5-ranlib
Checking for program 'rtems-ld'             : $BASE/rtems/5/bin/rtems-ld
Checking for program 'rtems-tld'            : $BASE/rtems/5/bin/rtems-tld
Checking for program 'rtems-syms'           : $BASE/rtems/5/bin/rtems-syms
Checking for program 'rtems-bin2c'          : $BASE/rtems/5/bin/rtems-bin2c
Checking for program 'tar'                  : /usr/bin/tar
Checking for program 'gcc, cc'              : $BASE/rtems/5/bin/sparc-rtems5-gcc
Checking for program 'ar'                   : $BASE/rtems/5/bin/sparc-rtems5-ar
Checking for program 'g++, c++'             : $BASE/rtems/5/bin/sparc-rtems5-g++
Checking for program 'ar'                   : $BASE/rtems/5/bin/sparc-rtems5-ar
Checking for program 'gas, gcc'             : $BASE/rtems/5/bin/sparc-rtems5-gcc
Checking for program 'ar'                   : $BASE/rtems/5/bin/sparc-rtems5-ar
Checking for c flags '-MMD'                 : yes
Checking for cxx flags '-MMD'               : yes
Compiler version (sparc-rtems5-gcc)         : 7.5.0 20191114 (RTEMS 5, RSB 5.1.0, Newlib fbaa096)
Checking for a valid RTEMS BSP installation : yes
Checking for RTEMS_DEBUG                    : no
Checking for RTEMS_MULTIPROCESSING          : no
Checking for RTEMS_NEWLIB                   : yes
Checking for RTEMS_POSIX_API                : yes
Checking for RTEMS_SMP                      : no
Checking for RTEMS_NETWORKING               : no
'configure' finished successfully (0.686s)

Build the application:

./waf

The output will be something close to:

Waf: Entering directory `$BASE/app/hello/build/sparc-rtems5-erc32'
[1/3] Compiling init.c
[2/3] Compiling hello.c
[3/3] Linking build/sparc-rtems5-erc32/hello.exe
Waf: Leaving directory `$BASE/app/hello/build/sparc-rtems5-erc32'
'build-sparc-rtems5-erc32' finished successfully (0.183s)

Run the executable:

$HOME/quick-start/rtems/5/bin/rtems-run --rtems-bsps=erc32-sis build/sparc-rtems5-erc32/hello.exe

The output will be something close to:

RTEMS Testing - Run, 5.1.0
 Command Line: $BASE/rtems/5/bin/rtems-run --rtems-bsps=erc32-sis build/sparc-rtems5-erc32/hello.exe
 Host: FreeBSD hihi 12.1-RELEASE-p2 FreeBSD 12.1-RELEASE-p2 GENERIC amd64
 Python: 3.7.6 (default, Jan 30 2020, 01:18:54) [Clang 6.0.1 (tags/RELEASE_601/final 335540)]
Host: FreeBSD-12.1-RELEASE-p2-amd64-64bit-ELF (FreeBSD hihi 12.1-RELEASE-p2 FreeBSD 12.1-RELEASE-p2 GENERIC amd64 amd64)

 SIS - SPARC/RISCV instruction simulator 2.21,  copyright Jiri Gaisler 2019
 Bug-reports to jiri@gaisler.se

 ERC32 emulation enabled

 Loaded build/sparc-rtems5-erc32/hello.exe, entry 0x02000000

Hello World

*** FATAL ***
fatal source: 5 (RTEMS_FATAL_SOURCE_EXIT)
fatal code: 0 (0x00000000)
RTEMS version: 5.1.0
RTEMS tools: 7.5.0 20191114 (RTEMS 5, RSB 5.1.0, Newlib fbaa096)
executing thread ID: 0x08a010001
executing thread name: UI1
cpu 0 in error mode (tt = 0x101)
   107883  0200b6c0:  91d02000   ta  0x0
Run time     : 0:00:01.011474

Commit the application to the repository:

git add init.c hello.c wscript
git commit -m "My first RTEMS application."