# Development environment

## In this learning path

- [Introduction](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/migration/)
- [Porting methodology](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/migration/2_porting_methodology/)
- [Porting analysis](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/migration/3_porting_analysis/)
- [Development environment](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/migration/4_development_environment/)
- [Application porting](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/migration/5_application_porting/)
- [Run and evaluate](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/migration/6_run_evaluate/)
- [Evaluating performance on Arm hardware (Optional)](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/migration/7_alternative/)
- [Next Steps](https://learn.arm.com/learning-paths/embedded-and-microcontrollers/migration/_next-steps/)

The original application uses GNU Compiler Collection ([GCC](https://gcc.gnu.org/)) so you want to create a development environment with this compiler and with the same version (when possible). To migrate the application to `aarch64`, you can use the same `x86_64` machine you used to run the application. You can use an `aarch64` container for your development environment which allows you to compile and run the ported application on the `x86_64` machine.

See [Docker Engine](https://learn.arm.com/install-guides/docker/docker-engine/) for instructions how to install Docker in your Linux environment.

## GCC container

Use a text editor to create a file named `Dockerfile` with the following content:

```dockerfile
FROM ubuntu:22.04
ENV DEBIAN_FRONTEND=noninteractive

RUN apt-get update && apt-get -y install vim wget sudo git tar build-essential libopencv-dev cmake
RUN apt-get clean

ENV USER=ubuntu
RUN useradd --create-home -s /bin/bash -m $USER && echo "$USER:ubuntu" | chpasswd && adduser $USER sudo
RUN echo '%sudo ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers

WORKDIR /home/ubuntu
USER ubuntu
```

This defines the GCC development environment.

## Cross-platform build

The cross-platform build using `buildx` enables you to build an `aarch64` container on an `x86_64` machine. Once built, the cross-platform built container can be run on that same `x86_64` machine using QEMU behind the scenes, quite convenient!

To build the container, run the following command:

```bash
docker buildx build --platform linux/aarch64 -t sobel_gcc_example .
```

## Run the container

Finally, run the `aarch64` container on the `x86_64` machine. Because the application will open a few X windows to display the image results, you need to enable graphical display when launching the container.

Run the commands below:

```bash
xhost +local:*
docker run -it --rm --platform linux/aarch64 --net=host -e DISPLAY=$DISPLAY -v /tmp/.X11-unix/:/tmp/.X11-unix/ -v $HOME/.Xauthority:/home/ubuntu/.Xauthority sobel_gcc_example /bin/bash
```

Now that you have the development environment running, you can port the Sobel filter application.