Run Zephyr on QEMU

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Ciro Santilli 34 Updated 2024-10-28 Created 1970-01-01

Real hardware is for newbs. Real hardware is for newbs.

Tested on Ubuntu 23.10 we approximately follow instructions from: docs.zephyrproject.org/3.4.0/develop/getting_started/index.html stopping before the "Flash the sample" section, as we don't flash QEMU. We just run it.

sudo apt install --no-install-recommends git cmake ninja-build gperf \
  ccache dfu-util device-tree-compiler wget \
  python3-dev python3-pip python3-setuptools python3-tk python3-wheel xz-utils file \
  make gcc gcc-multilib g++-multilib libsdl2-dev libmagic1
python3 -m venv ~/zephyrproject/.venv
source ~/zephyrproject/.venv/bin/activate
pip install west
west init ~/zephyrproject
cd ~/zephyrproject
west update
west zephyr-export
cd ~
wget https://github.com/zephyrproject-rtos/sdk-ng/releases/download/v0.16.1/zephyr-sdk-0.16.1_linux-x86_64.tar.xz
tar xvf zephyr-sdk-0.16.1_linux-x86_64.tar.xz
cd zephyr-sdk-0.16.1
./setup.sh

The installation procedure install all compiler toolchains for us, so we can then basically compile for any target. It also fetches the latest Git source code of Zephyr under:

~/zephyrproject/zephyr

The "most default" blinky hello world example which blinks an LED is a bit useless for us because QEMU doesn't have LEDs, so instead we are going to use one of the UART examples which will print characters we can see on QEMU stdout.

Let's start with the hello world example on an x86 target:

cd ~/zephyrproject/zephyr
west build -b qemu_x86 samples/hello_world -t run

and it outputs:

Hello World! qemu_x86

The qemu_x64 on the output comes from the CONFIG_BOARD macro github.com/zephyrproject-rtos/zephyr/blob/c15ff103001899ba0321b2c38013d1008584edc0/samples/hello_world/src/main.c#L11

#include <zephyr/kernel.h>

int main(void)
{
	printk("Hello World! %s\n", CONFIG_BOARD);
	return 0;
}

The qemu_x86 board is documented at: docs.zephyrproject.org/3.4.0/boards/x86/qemu_x86/doc/index.html

You can also first cd into the directory that you want to build in to avoid typing samples/hello_world all the time:

cd ~/zephyrproject/zephyr/samples/hello_world
zephyr west build -b qemu_x86 -t run

You can also build and run separately with:

west build -b qemu_x86
west build -t run

Another important option is:

west build -t menuconfig

But note that it does not modify your prj.conf automatically for you.

Let's try on another target:

rm -rf build
zephyr west build -b qemu_cortex_a53 -t run

and same output, but on a completely different board! The qemu_cortex_a53 board is documented at: docs.zephyrproject.org/3.4.0/boards/arm64/qemu_cortex_a53/doc/index.html

The list of all examples can be seen under:

ls ~/zephyrproject/zephyr/samples

which for example contains:

zephyrproject/zephyr/samples/hello_world

So run another sample simply select it, e.g. to run zephyrproject/zephyr/samples/synchronization:

west build -b qemu_cortex_a53 samples/synchronization -t run

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