Booting up a QEMU image¶
Images for QEMU target can be booted up using KVM 1 to utilize hardware virtualization feature if found on the host system and run the virtual machine in better performance. See KVM feature for QEMU 2.
QEMU launch script¶
There is a QEMU launch script called
qemu_launcher, which is shipped with SDK and also available from yocto builds.
$ ./qemu_launcher -h usage: ./qemu_launcher [options] [options] is any of the following: -f | --folder Specify a source folder of the QEMU image Defaults to tmp/deploy/images/qemux86-64 -i | --hda Specify rootfs file. Defaults to core-image-pelux-minimal-qemux86-64.ext4 -p | --ssh_port SSH port to connet to QEMU. Defaults to 1234 -n | --smp Number of cpu cores. Defaults to 4 -k | --kernel_path By default, kernel_path is the same as folder, but can be overwritten by using this option -c | --cmdline Specify kernel command line. This would allow power users to change vga or root, etc. Defaults to "vga=0 uvesafb.mode_option=1280×720-32 root=/dev/hda console=ttyS0 rw oprofile.timer=1" -m | --mem Maximum amount of guest memory (Size is in megabytes) Defaults to 512 -t | --gdb_port The port is forwarded so that gdbserver can listen on it Then gdb can be run from develop machine to connect to the port for remote debugging Defaults to 3333 -d | --dev Run QEMU development image instead of normal image Defaults to core-image-pelux-minimal-dev-qemux86-64.ext4 -s | --static The switch to toggle running QEMU dev image with static IP (Defaults to false) -I | --target_ip Specify the target static IP, must be 192.168.7.x (Defaults to 192.168.7.2) Please aware that to change the default static IP, it is also needed to update the STATIC_IP_ADDRESS in local.conf in meta layer and rebuild the image -g | --server_ip Specify the gateway server IP, must be 192.168.7.x (Defaults to 192.168.7.1) -l | --list List all available images from the default folder or folder user specified -h | --help Display this help
Launching the virtual machine¶
QEMU can be launched with different network backend configurations.
Port forwarding configuration¶
QEMU emulator can be launched with serial console support and port forwarding using the following command:
./qemu_launcher -f FOLDER -i core-image-pelux-minimal-qemux86-64.ext4
The above command will load kernel and the image
Static IP address configuration¶
A static IP address facilitates development of automation and testing scripts.
The next commands assume the QEMU target ip address is
192.168.7.2 and the
host machine address is
1. Launch QEMU with static IP address and a tap device 3 using the following command:
./qemu_launcher -f FOLDER -i core-image-pelux-minimal-qemux86-64.ext4 -s
The above script will launch QEMU with a tap device
tap0 on the host machine
where guest networking can be routed through the tap interface.
To achieve that run the following command inside the guest machine console:
route add default gw 192.168.7.1
2. Configure the
tap0 interface on host machine by executing the following
commands on the host machine:
sudo ip address add 192.168.7.1/24 broadcast 192.168.7.255 dev tap0 sudo ip link set dev tap0 up
3. (Optional) Enable the tap device to access internet by running the following commands on the host machine:
sudo ip route add to 192.168.7.1 dev tap0 sudo iptables -A POSTROUTING -t nat -j MASQUERADE -s 192.168.7.1/24 sudo iptables -P FORWARD ACCEPT
Instead of using the default target IP
192.168.7.2 and the server address
192.168.7.1, it is possible to specify the target IP and server IP as shown below:
./qemu_launcher -f FOLDER -i core-image-pelux-minimal-qemux86-64.ext4 -s --target_ip 192.168.11.18 --server_ip 192.168.11.1
Please aware that to make the new static IP work, it is also needed to update
local.conf in meta layer and rebuild the image.
Supported emulated hardware configuration¶
Number of cpu cores
Maximum amount of guest memory
QXL video graphics output
AC'97 audio audio codec
hostfwd option specifies TCP port configuration for ssh usage.
If you build another image than
core-image-pelux-minimal, adapt the path passed to
Connecting to the virtual machine using SSH¶
The machine can be accessed via SSH for development purposes.
SSH access via Port forwarding¶
Boot the QEMU machine with port forwarding configuration
Port forwarding configuration, where QEMU target port
22 for the
localhost interface is mapped to host machine port
1234 for its
Then Run the
ssh command on host machine.
$ ssh firstname.lastname@example.org -p 1234
SSH access via static ip¶
Boot the QEMU machine with static ip configuration, and then run the following command on host machine.
$ ssh email@example.com -p 22