Raspbian on QEMU with ARMv7

Emulate Raspbian on QEMU with ARMv7 using Buildroot to configure your kernel and set a Python environment to run scripts using Keras on Tensorflow.

TL;DR

Use the Shell scripts at root (you may need to enable execution with chmod +x <script>.sh). Details of what's happening in these scripts are in sections below.

• To download and build files, run the following script:

./download_and_build.sh

• To run Raspbian on QEMU using created files, run the following script:

./run_raspbian_on_qemu.sh

Download and build files

Download and unzip the image of Raspbian (the version fetched here is the lite, you may switch to what you need):

wget http://downloads.raspberrypi.org/raspbian_lite/images/raspbian_lite-2018-11-15/2018-11-13-raspbian-stretch-lite.zip
unzip 2018-11-13-raspbian-stretch-lite.zip

Download and untar Buildroot package:

wget http://www.buildroot.org/downloads/buildroot-2019.02.tar.bz2
tar xf buildroot-2019.02.tar.bz2

Set Buildroot configuration file to build QEMU ARM using V-Express and start:

cd buildroot-2019.02/
make qemu_arm_vexpress_defconfig
make

Output files are located in the output/images folder. This will create default rootfs, the kernel to be used zImage and the DTB vexpress-v2p-ca9.dtb.

You now have everything needed to start Raspbian on QEMU.

Start Raspbian on QEMU

Install QEMU if needed an run the following command (if needed, adapt the path to local files):

qemu-system-arm \
        -M vexpress-a9 \
        -m 256 \
        -kernel vexpress/zImage \
        -dtb vexpress/vexpress-v2p-ca9.dtb \
        -sd 2018-11-13-raspbian-stretch.img \
        -append "console=ttyAMA0,115200 root=/dev/mmcblk0p2" \
        -serial stdio \
        -net nic -net user,hostfwd=tcp::2222-:22

If everything went well, Raspbian should boot (default username and password of Raspbian are pi and raspberry respectively).

You may enable SSH using sudo raspi-config from Raspbian, go to Interfacing Options, SSH and select <Yes>. After that, you may access your emulated Raspbian machine using SSH from your local OS:

ssh -p 2222 pi@localhost

Password is required to establish connection.

Resize Pi's filesystem

On the host, run

qemu-img resize <image_name>.img +<size>G

Then, on the PI, run

sudo fdisk /dev/mmcblk0

fdisk is in interactive mode by default. Run sequentially :

>p  #Get the first segment for /dev/mmcblk0p2 (probably 98304)
>d
>2
>n
>2
>p
>98304
>w

then reboot the pi

sudo reboot -h now

then, on the pi, run

sudo resize2fs /dev/mmcblk0p2

Now your Pi has more space on filesystem

Ansible

Be careful to update the file ansible/inventories/hosts with the right password for the pi. To launch playbooks, at the root of the project, run

ansible-playbook -i ansible/inventories ansible/<name_of_playbook.yml>

You need to first connect to the pi through ssh

Integration test

Copy the files in data_for_integration_test on the pi (scp for example) Copy the image in qemu_files you want to boot on the pi (with dd for example) Boot the Pi Run the code, with python3 interpreter, in snippet_integration.py. Please be careful with paths for model and images