Thursday, November 6, 2014

Adventures in setting up local lava service

Linaro uses LAVA as a tool to test variety of devices. So far I had not installed it myself, mostly due to assuming it to be enermously complex to set up. But thanks to Neil Williams work on packaging, installation has got a lot easier. Follow the Official Install Doc and Official install to debian Doc, roughly looking like:

1. Install Jessie into kvm

kvm -m 2048 -drive file=lava2.img,if=virtio -cdrom debian-testing-amd64-netinst.iso
2. Install lava-server
apt-get update; apt-get install -y postgresql nfs-kernel-server apache2
apt-get install lava-server
# answer debconf questions
a2dissite 000-default && a2ensite lava-server.conf 
service apache2 reload
lava-server manage createsuperuser --username default
$EDITOR /etc/lava-dispatcher/lava-dispatcher.conf # make sure LAVA_SERVER_IP is right
That's the generic setup. Now you can point your browser to the IP address of the kvm machine, and log in with the default user and the password you made.

3 ... 1000 Each LAVA instance is site customized for the boards, network, serial ports, etc. In this example, I now add a single arndale board.

cp /usr/lib/python2.7/dist-packages/lava_dispatcher/default-config/lava-dispatcher/device-types/arndale.conf /etc/lava-dispatcher/device-types/
sudo /usr/share/lava-server/ -s arndale arndale-01 -t 7001
This generates us a almost usable config for the arndale. For site specifics I have usb-to-serial. Outside kvm, I provide access to serial ports using the following ser2net config:
7001:telnet:0:/dev/ttyUSB0:115200 8DATABITS NONE 1STOPBIT
7002:telnet:0:/dev/ttyUSB1:115200 8DATABITS NONE 1STOPBIT
TODO: make ser2net not run as root and ensure usb2serial devices always get same name..

For automatic power reset, I wanted something cheap, yet something that wouldn't require much soldering (I'm not a real embedded engineer.. I prefer software side ;) . Discussed with Hector, who hinted about prebuilt relay boxes. Chose one from Ebay, a kmtronic 8-port USB Relay. So now I have this cute boxed nonsense hack.

The USB relay is driven with a short script, hard-reset-1

stty -F /dev/ttyACM0 9600
echo -e '\xFF\x01\x00' > /dev/ttyACM0
sleep 1
echo -e '\xFF\x01\x01' > /dev/ttyACM0
Sidenote: If you don't have or want automated power relay for lava, you can always replace this this script with something along "mpg123 puny_human_press_the_power_button_now.mp3"

Both the serial port and reset script are on server with dns name aimless. So we take the /etc/lava-dispatcher/devices/arndale-01.conf that created and make it look like:

device_type = arndale
hostname = arndale-01
connection_command = telnet aimless 7001
hard_reset_command = slogin lava@aimless -i /etc/lava-dispatcher/id_rsa /home/lava/hard-reset-1
Since in my case I'm only going to test with tftp/nfs boot, the arndale board needs only to be setup to have a u-boot bootloader ready on power-on.

Now everything is ready for a test job. I have a locally built kernel and device tree, and I export the directory using the httpd available by default in debian.. Python!

cd out/
python -m SimpleHTTPServer
Go to the lava web server, select api->tokens and create a new token. Next we add the token and use it to submit a job
$ sudo apt-get install lava-tool
$ lava-tool auth-add http://default@lava-server/RPC2/
$ lava-tool submit-job http://default@lava-server/RPC2/ lava_test.json
submitted as job id: 1
The first job should now be visible in the lava web frontend, in the scheduler -> jobs part. If everything goes fine, the relay will click in a moment and the job will finish in a few minutes.

Saturday, November 1, 2014

Using networkd for kvm tap networking

Setting up basic systemd-network was recently described by Joachim, and the post inspired me to try it as well. The twist is that in my case I need a bridge for my KVM with Lava server and arm/aarch64 qemu system emulators...

For background, qemu/kvm support a few ways to provide network to guests. The default is user networking, which requires no privileges, but is slow and based on ancient SLIRP code. The other common option is tap networking, which is fast, but complicated to set up. Turns out, with networkd and qemu bridge helper, tap is easy to set up.

$ for file in /etc/systemd/network/*; do echo $file; cat $file; done



Diverging from Joachims simple example, we replaced "DHCP=yes" with "Bridge=br0". Then we proceed to define the bridge (in the kvm.netdev) and give it an ip via dhcp in From the kvm side, if you haven't used the bridge helper before, you need to give the helper permissions (setuid root or cap_net_admin) to create a tap device to attach on the bridge. The helper needs an configuration file to tell what bridge it may meddle with.
# cat > /etc/qemu/bridge.conf <<__END__
allow br0
# setcap cap_net_admin=ep /usr/lib/qemu/qemu-bridge-helper
Now we can start kvm with bridge networking as easily as with user networking:
$ kvm -m 2048 -drive file=jessie.img,if=virtio -net bridge -net nic,model=virtio -serial stdio
The manpages and systemd.netdev(5) do a great job explaining the files. Qemu/kvm networking docs are unfortunately not as detailed.