Hello World in C/C++
Introduction
This article provides step-by-step instructions on how to cross-compile a simple Hello World application on the development host through command-line or by using an IDE. It also gives instructions on how to run the application on the target device.
Follow the Embedded Linux environment setup article for information on setting up your environment for Embedded Linux application development.
Toolchain/SDK
To compile an application for the SoM, first we need a Toolchain that can generate ARM binaries and link them to libraries present in the SoM Operating System.
Use BitBake to build and install the Software Development Kit (SDK) for your SoM, as described in the Linux SDKs article. The SDK comes with a toolchain for the SoM and other important elements such as the sysroot
.
Application
In this example, the project path is ~/Documents/embedded/hello-world-c/
.
The following steps guide you through the creation of the classic Hello World
application in C:
- Create a directory for your project:
mkdir -p ~/Documents/embedded/hello-world-c/
cd
to the project folder:
cd ~/Documents/embedded/hello-world-c/
- Create the
hello_world.c
file in the project directory, then paste the Hello World code:
#include <stdio.h>
int main() {
printf("Hello World!\n");
return 0;
}
Compilation
source
theenvironment-setup
script from SDK section.
Assuming the SDK is installed in the default location (/opt/<distro>/<version>/environment-setup-...
):
source /opt/tdx-xwayland/6.3.0/environment-setup-...
- Use the SDK toolchain to build the application:
$CC $CFLAGS hello_world.c -o hello_world
The environment-setup
script exports variables such as:
$CC
: The C compiler.$CFLAGS
: The C build flags.$CXX
: The C++ compiler.$CXXFLAGS
: The C++ build flags.$LDFLAGS
: The linker flags.
And also provides a pkg-config
tool.
A binary executable named hello_world
should appear in the directory.
Execution
- Copy the application to the SoM using tools such as
scp
,sftp
, or use a USB stick. - Connect to the module, either by
ssh
or by serial. cd
to thehello_world
application directory.- Run the application:
./hello_world
A message showing Hello World!
should appear in your terminal.
If you try to run the program on a x86 machine, the system will show an exec format error:
bash: ./hello_world: cannot execute binary file: Exec format error
CMake
BitBake's populate_sdk
command can be configured to add CMake support to the SDK — which also configures the environment-setup
script to set CMake options — making cross compilation transparent to the user.
SDK support
Add CMake support to your SDK (see SDK section) by adding the following line to your build/conf/local.conf
file:
TOOLCHAIN_HOST_TASK:append = " nativesdk-cmake"
Then re-build and install your new SDK.
Project Configuration
Create the CMakeLists.txt
file in your C project directory, then paste the following code:
cmake_minimum_required(VERSION 3.21)
project(
CMakeHelloWorld
VERSION 1.0
LANGUAGES C)
add_executable(cmake_hello_world hello_world.c)
Compilation
In your project directory:
- Create the
build
folder:
mkdir -p ~/Documents/embedded/hello-world-c/build/
- Change directory to the
build
folder:
cd ~/Documents/embedded/hello-world-c/build/
- Source the environment script from the new SDK, to load tools such as
pkg-config
and CMake environment configuration.
Assuming the SDK is installed in the default location (/opt/<distro>/<version>/environment-setup-...
):
source /opt/tdx-xwayland/6.3.0/environment-setup-...
- Run CMake to generate the makefile:
cmake ..
- Run
make
to build the application:
make
A binary executable named cmake_hello_world
should appear in the directory.
Follow the instructions from Execution section on how to send the executable to the SoM and run the application.
IDE integration
Some popular IDEs allow using it as the build system for C/C++ projects:
- CLion
- KDevelop
- QtCreator
- Visual Studio
To be able to cross-compile, you may need to configure your IDE to source the environment-setup
script. A list of IDEs that support CMake is available in CMake documentation.