Migration to Scaleway ARM server

The C1 Server

Scaleway started selling ARM based hosted server in April. I've intended to blog about this for a while, since it was time to upgrade from wheezy to jessie was timely, why not switch provider from an X86 based to ARM one at the same time?

In many ways scaleway node is opposite to what "Enterprise ARM" people are working on. Each server is based on an oldish ARMv7 Quad-Core Marvell Armada XP, instead of a brand new 64-bit ARMv8 cpu. There is no UEFI, ACPI or any other "industry standards" involved, just a smooth web interface and a command line tool to manage your node(s). And the node is yours, it's not shared with others with virtualization. The picture above is a single node, which is stacked with 911 other nodes into a single rack.

This week, the C1 price was dropped to a very reasonable €2.99 per month, or €0.006 per hour.

Software runs on hardware, news at 11

The performance is more than enough for my needs - shell, email and light web serving. dovecot, postfix, irssi and apache2 are just an apt-get away. Anyone who says you need x86 for Linux servers is forgetting that Linux software is open source, and if not already available, can be compiled to any architecture with little effort. Thus the migration pains were only because I chose to modernize configuration of dovecot and friends. Details of the new setup shall be left for another post.

Dystopia of Things

The Thing on Internet

I've now had an "Internet of Things" device for about a year. It is Logitech Harmony HUB, an universal remote controller. It comes with a traditional remote, but the interesting part is that it allows me to use my smartphone/tablet as remote over WiFi. With the android app it provides a rather nice use experience, yet I can see the inevitable end in anger.

Bare minimum GPL respect

Today, the GPL sources for hub are available - at least the kernel and a patch for busybox. The proper GPL release is still only through written offer. The sources appeared online April this year while Hub has been sold for two years already. Even if I ordered the GPL CD, it's unlikely I could build a modified system with it - too many proprietary bits. The whole GPL was invented by someone who couldn't make a printer do what he wanted. The dystopian today where I have to rewrite the whole stack running on a Linux-based system if I'm not happy what's running there as provided by OEM.

App only

The smartphone app is mandatory. The app is used to set up the hub. There is no HTML5 interface or any other way to control to the hub - just the bundled remote and phone apps. Fully proprietary apps, with limited customization options. And if app store update removes a feature you have used.. well you can't get it from anywhere anymore. The dystopian today where "Internet of Things" is actually "Smartphone App of Things".

Locked API

Maybe instead of modifying the official app you could write your own UI? Like one screen with only the buttons you ever use when watching TV? There *is* an API with delightful headline "Better home experiences, together". However, not together with me, the owner of the harmony hub. The official API is locked to selected partners. And the API is not to control the hub - it's to let the hub connect to other IoT devices. Of course, for talented people, locked api is usually just undocumented api. People have reverse engineered how the app talks to the hub over wifi. Curiously it is actually Jabber based with some twists like logging credentials through Logitech servers. The dystopian today where I can't write programs to remotely control the internet connected thing I own without reverse engineering protocols.

Central Server

Did someone say Logitech servers? Ah yes, all configuring of the remote happens via myharmony servers, where the database of remote controllers lives. There is some irony in calling the service *my* harmony when it's clearly theirs. The communication with cloud servers leaks at minimum back to Logitech what hardware I control with my hub. At the worst, it will become an avenue of exploits. And how long will Logitech manage these servers? The moment they are gone, harmony hub becomes a semi-brick. It will still work, but I can't change any configuration anymore. The dystopian future where the Internet of Thing will stop working *when* cloud servers get sunset

What now

This is not just the Harmony hub - this is a pattern that many IoT products follow - Linux based gadget, smartphone app, cloud services, monetized apis. After the gadget is bought, the vendor has little incentive to provide any updates. After all, the next chance I'll carry them money is when the current gadget gets obsolete.

I can see two ways out. The easy way is to get IoT gadgets as monthly paid service. Now the gadget vendor has the right incentive - instead of trying to convince me to buy their next gadget, their incentive is to keep me happily paying the monthly bill. The polar opposite is to start making open competing IoT's, and market to people the advantage of being yourself in control. I can see markets for both options. But half-way between is just pure dystopy.

Fastest way to change running dtb

Tollef posted about using BeagleBone Black for temperature monitoring. There was a passage about patching the DTB (device tree) file:

... This needs to be compiled into a .dtb. I found the easiest way was just to drop the patched .dts into an unpacked kernel tree and then running make dtbs.

There are easier ways. For example, you can get the current device tree file generated from /proc:

apt-get install device-tree-compiler
dtc -I fs -O dts -o current.dts /proc/device-tree/

(Why /proc and not /sys ? because device tree predates /sys) Now you can just modify and build the dtb again, and install it back to where bootloader reads the dtb from:

vim current.dts
dtc -I dts -O dtb -o new.dtb current.dts

Alternative, of course, is to build a brand new mainline kernel and use the dynamic Device tree code now available.

Crowdfunding better GCompris graphics

GCompris is the most established open source kids educational game. Here we practice use of mouse with an Efika smartbook. In this subgame, mouse is moved around to uncover a image behind.

While GCompris is nice, it needs nice graphics badly. Now the GCompris authors are running a indiegogo crowfund exactly for that - to get new unified graphics.

Why should you fund? Apart from the "I want to be nice for any oss project", I see a couple of reasons specific for this crowdfund.

First, to show kids that apps can be changed! Instead of just using existing iPad apps as a consumer, Gcompris allows you to show kids how games are built and modified. With the new graphics, more kids will play longer, and eventually some will ask if something can be changed/added..

Second, GCompris has recently become QT/QML based, making it more portable than before. Wouldn't you like to see it in your Jolla tablet or a future Ubuntu phone? The crowfund doesn't promise to make new ports, but if you are eager to show your friends nice looking apps on your platform, this probably one of the easiest ways to help them happen.

Finally, as a nice way to say happy new year 2015 :)

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 --email=foo.bar@example.com
$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/add_device.py -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 add_device.py 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.

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
/etc/systemd/network/eth.network
[Match]
Name=eth1
[Network]
Bridge=br0

/etc/systemd/network/kvm.netdev
[NetDev]
Name=br0
Kind=bridge

/etc/systemd/network/kvm.network
[Match]
Name=br0
[Network]
DHCP=yes

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 kvm.network. 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
__END__
# 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 systemd.network(5) and systemd.netdev(5) do a great job explaining the files. Qemu/kvm networking docs are unfortunately not as detailed.

Booting Linaro ARMv8 OE images with Qemu

A quick update - Linaro ARMv8 OpenEmbbeded images work just fine with qemu 2.1 as well:

$ http://releases.linaro.org/14.07/openembedded/aarch64/Image
$ http://releases.linaro.org/14.07/openembedded/aarch64/vexpress64-openembedded_lamp-armv8-gcc-4.9_20140727-682.img.gz
$ qemu-system-aarch64 -m 1024 -cpu cortex-a57 -nographic -machine virt \
 -kernel Image -append 'root=/dev/vda2 rw rootwait mem=1024M console=ttyAMA0,38400n8' \
 -drive if=none,id=image,file=vexpress64-openembedded_lamp-armv8-gcc-4.9_20140727-682.img \
 -netdev user,id=user0 -device virtio-net-device,netdev=user0  -device virtio-blk-device,drive=image 
[    0.000000] Linux version 3.16.0-1-linaro-vexpress64 (buildslave@x86-64-07) (gcc version 4.8.3 20140401 (prerelease) (crosstool-NG linaro-1.13.1-4.8-2014.04 - Linaro GCC 4.8-2014.04) ) #1ubuntu1~ci+140726114341 SMP PREEMPT Sat Jul 26 11:44:27 UTC 20
[    0.000000] CPU: AArch64 Processor [411fd070] revision 0
...
root@genericarmv8:~# 

Quick benchmarking with age-old ByteMark nbench:

Index	Qemu	Foundation	Host
Memory	4.294	0.712	44.534
Integer	6.270	0.686	41.983
Float	1.463	1.065	59.528
Baseline (LINUX) : AMD K6/233*

Qemu is upto 8x faster than Foundation model on Integers, but only 50% faster on Math. Meanwhile, the Host pc spends 7-40x slower emulating ARMv8 than executing native instructions.