= Run Zephyr on QEMU
{tag=QEMU}
Real hardware is for newbs. Real hardware is for newbs.
Tested on <Ubuntu 23.10> we approximately follow instructions from: https://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 https://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: https://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: https://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
``