Colors of Noise

agx@sigxcpu.org

Bits from the 7th Debian groupware meeting
29th April 2014

The seventh Debian Groupware Meeting was held in the LinuxHotel, Essen, Germany. We had one remote hacker from NYC which brings the number of attendants up to 9. This is a short summary of what happened during the weekend:

Since we had a nice mix of first time Debian contributors, Debian Maintainers and Debian Developers we had lots of room for discussion and co-working which made this an exciting weekend.

Groupphoto by Carsten Schönert

Tags: debian, planetdebian, planetfsfe.
Truncating git history
21st February 2014

When starting to work on a new project I start from an empty git repository right away so I can try out different ideas, revert easily, can diff against old versions (to check if I missed something) and have a commit history to record fixmes and todos. However when making the repo public these things are not of much interest anymore so I truncate the history. To be on the save side I want to keep that history locally though. Assuming the repo is on master, I do:

# 1.) Move the old master out of the way
git branch -m branch master oldmaster
# 2.) Get the current tree at HEAD
tree=$(git rev-parse HEAD^{tree})
# 3.) Create a new commit without ancestry
commit=$(git commit-tree -m "Initial commit" $tree)
# 4.) Make this the new master
git branch master $commit
# 5.) Switch to the new branch
git checkout master

Done. One can now add a remote and push the master branch. The old history is still there locally on the completely detached commit history ending at oldmaster:

$ git log --pretty=short --graph --decorate master oldmster

* commit d5cf3371eaefbaa8efac10c0fb9e7597da17b423 (HEAD, master)
  Author: Guido Günther <agx@sigxcpu.org>

      Initial commit

* commit 64103ff72bde13d7ec4cf0489ad2a80f3ac249d3 (oldmster)
| Author: Guido Günther <agx@sigxcpu.org>
|
|     Another uninteresting commit message
|
* commit bd7332a79380bb217eca09cbd7f6ff0e5174deb8
| Author: Guido Günther <agx@sigxcpu.org>
|
|     Uninteresting commit message
|
... <more old history>

Update: Uli Heller pointed out that this is the same as using git checkout's --orphan option.

Tags: planetdebian, planetfsfe.
whatmaps 0.0.3
7th January 2014

I have just released whatmaps 0.0.3 a tool to check which processes map shared objects of a certain package. It can integrate into apt to automatically restart services after a security upgrade.

This release fixes a problem where we tried to look at already terminted processes. It also works now on systems without lsb_release installed.

This blog is flattr enabled.

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CrystalHD progress
30th November 2013

Following up on my port of the crystalhd plugin to the gstreamer 1.0 api I realized that the CrystalHD repo is pretty dormant. After reading slomo's nice article about GStreamer and hardware integration and a short off list mail exchange I decided to split the GStreamer part out of the CrystalHD repo and to try to get the plugin into gst-plugins-bad.

Since the kernel part is already in linux kernel's staging area there would not be much left in the repo except for the libcrystalhd library itself and the firmware blobs. So I split them out as well and started to clean them up a bit by moving it to autoconf/automake, dropping the need for a C++ compiler and adding symbol versioning among other things.

So up to know video is still smooth with:

gst-launch-1.0 filesrc location=sample.mp4 ! decodebin ! xvimagesink

after jhbuilding up to gst-plugins-bad.

There are #ifdefs for macosx and windows but I doubt they're functional but in case anybody is building libcrystalhd on these these platforms it'd be great to know if it still works.

Should these efforts lead to the crystalhd plugin being merged into GStreamer getting the kernel driver out of staging would be a great next step.

This blog is flattr enabled.

Tags: gnome, planetdebian, planetfsfe, planetgnome, wetab.
Monitoring the temparature values of a Ökofen Pellematic using munin
3rd September 2013

I recently had the joy to adjust a heating system powered by a Ökofen Pellematic pellet boiler. It turned out that the heating control for that system has a small web interface running on a Linux system that allows one to set the different temperature values.

The different temperature values can be queried easily using python-request and then graphed via a simple munin plugin:

Temperatures of the pellet boiler

The sources are available here. Several more plugins for the different pumps and switches are already in the works. This needs some more work though to avoid lots of copy and paste.

Sadly enough there's no SSL available in the web interface. I already contacted the vendor about that and about the GPLed parts of their software so there's more to come.

This blog is flattr enabled.

Tags: munin, planetfsfe.
Calendar synchronisation between Nokia N900 and the Calypso CalDAV server
5th June 2013

One of the replies to the post about Debian's last groupware meeting was from Patrick Ohly of syncevolution fame pointing out that syncevolution already implements calendar autodetection for CalDAV calendars as described in draft-daboo-srv-caldav-10.

While looking at the code I noticed that there's a backend for the N900s calendar by Ove Kåven as well.

When I tried Ove's latest package on my N900 it lead to an immediate crash when doing a:

syncevolution --print-items target-config@webdav calendar

According to Patrick the bug was supposed to be fixed in recent versions so I set up scratchbox and built a newer git snapshot for maemo (sources). This wouldn't crash but didn't show up any items either. It turned out to be a minor bug in calypso returning no content type for REPORT queries which resulted in libneon discarding the whole reply (now already fixed in calypso upstream).

With this out of the way setting up synchronisation is quiet simple:

# Configuration
CALDAV_SERVER=192.168.0.10
syncevolution --configure username=<username> password=<password> \
              calendar/backend=caldav calendar/database=https://${CALDAV_SERVER}:5233/private/my_calendar \
              target-config@webdav calendar
syncevolution --configure --template SyncEvolution_Client sync=none syncURL=local://@webdav username= password= webdav
syncevolution --configure sync=two-way backend=calendar webdav calendar

You should then be able to print the items on the local (N900) and from the remote (CalDAV server) end:

# This lists the current calendar items on the server
syncevolution --print-items target-config@webdav calendar
# This lists the current calendar items on the N900
syncevolution --print-items @default calendar

And from there on sync away:

# initial slow sync
syncevolution --sync slow webdav
# from there on
syncevolution webdav

The syncevolution source code has great documentation about debugging problems (e.g. src/backends/webdav/README). So check that in case you run into problems. The tl;dr version is

SYNCEVOLUTION_DEBUG=1 src/syncevolution loglevel=10 --print-items target-config@webdav calendar

to debug CalDAV related problems. In case you need to run syncevoluton from source be sure to set these beforehand:

export SYNCEVOLUTION_TEMPLATE_DIR=$PWD/src/templates/
export SYNCEVOLUTION_XML_CONFIG_DIR=$PWD/src/syncevo/configs/

On the CalDAV side I used current Calypso git which (with some additional minor fixes) now also interoperates nicely with Iceowl/Icowl-Extension aka Sunbird/Lightning on the desktop side. There's also an ITP for it. So it'll hopefully end up in Debian soon.

Update: in order to do ssl verification with syncevolution/libneon you have to put the CAs certificate to /etc/ssl/certs on the N900 and do a

c_rehash /etc/ssl/certs

otherwise syncevolution won't ve able to verify the server's certificate.

Tags: debian, groupware, maemo, planetdebian, planetfsfe.
Bits from the 6th Debian groupware meeting
29th April 2013

The sixth Debian Groupware Meeting was held in the LinuxHotel, Essen, Germany. We had one remote hacker from NYC which brings the number of attendants up to nine - an all time high! This is a short summary of what happened during the weekend:

Groupphoto by Carsten Schönert

Tags: debian, planetdebian.
gst0.10-crystalhd ported to gstreamer 1.0
22nd March 2013

Following up on using Debian on the WeTab with GNOME Shell I figured accelerated video using the built in CrystalHD to save battery power and CPU cycles would be nice to have. There's even a Debian package available but not for gstreamer 1.0 (which is used by GNOME 3.6) so I had a look at gstreamer's plugin writers guide and porting guide and updated the driver. Packages are here until there's a new upstream version or Debian package release.

This blog is flattr enabled.

Tags: gnome, planetdebian, planetgnome, wetab.
Accelerometer and screen orientation in GNOME3
23rd February 2013

Following up on using Debian on the WeTab with GNOME Shell I had a look at automatically adjusting the screen orientation when rotating the device.

The accelerometer is handled in the asus_laptop module since kernel 3.2, so this shows up in /proc/bus/input/devices:

I: Bus=0019 Vendor=0000 Product=0000 Version=0000
N: Name="Pegatron Lucid Tablet Accelerometer"
P: Phys=pega_accel/input0
S: Sysfs=/devices/platform/asus_laptop/input/input4
U: Uniq=
H: Handlers=event4 js0 
B: PROP=0
B: EV=9
B: ABS=7

Whenever the screen orientation changes the driver emits a udev event. The helper in /lib/udev/accelerometer processes it thanks to /lib/udev/rules.d/61-accelerometer.rules, determines the orientation and adds the ID_INPUT_ACCELEROMETER_ORIENTATION property to the event which can be checked with udevadm monitor --property:

UDEV  [5778.534171] change   /devices/platform/asus_laptop/input/input4 (input)
ABS=7
ACTION=change
DEVPATH=/devices/platform/asus_laptop/input/input4
EV=9
ID_FOR_SEAT=input-platform-asus_laptop
ID_INPUT=1
ID_INPUT_ACCELEROMETER=1
ID_INPUT_ACCELEROMETER_ORIENTATION=right-up
ID_PATH=platform-asus_laptop
ID_PATH_TAG=platform-asus_laptop
MODALIAS=input:b0019v0000p0000e0000-e0,3,kra0,1,2,mlsfw
NAME="Pegatron Lucid Tablet Accelerometer"
PHYS="pega_accel/input0"
PRODUCT=19/0/0/0
PROP=0
SEQNUM=1550
SUBSYSTEM=input
TAGS=:seat:
UDEV_LOG=3
USEC_INITIALIZED=6154288

This is captured by gnome-settings-daemon (>=3.2) that adjusts the screen rotation using xrandr2 accordingly. This can be checked by running gnome-settings-daemon with --debug. The old way of using xinput events is no longer supported.

Unfortunately Debian's udev has a minor bug that misdetects the input device so this patch is needed to have the screen orientation changed automatically on the WeTab.

This blog is flattr enabled.

Tags: gnome, planetdebian, wetab.
GTK+3 CSS for touch screens
17th February 2013

Following up on using Debian on the WeTab with GNOME Shell I've put together a bit of GTK+3 CSS to make it more touch friendly. It's in the same git repo as the OSK extension. If you put the gtk.css into ~/.config/gtk-3.0/gtk.css scrollbars will be a bit larger and the padding between widgets will be increased over the default theme:

Larger scroll bar Larger scroll bar

This will need more work since some of the sliders look a bit a awkward now so any enhancements will be greatly appreciated. The docs for GTK3's CSS are here.

This blog is flattr enabled.

Tags: gnome, planetdebian.

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