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Get some rest or making KDE more power efficient April 9, 2010

Posted by lurchi in Computer, KDE, Powersaving, Qt.
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This article is about saving the world. At least, give our small green planet a chance to last until it is eaten by this red dwarf called sun.

Motivated by an article and my recent purchase of a new laptop, I went looking for some reasons for the mismatch in power usage of KDE vs the other DEs. Although is was not worried about the differences in memory usage (others have commented on measuring memory usage correctly in depth), the increase of power usage between the beginning of the benchmark and the end struck me. As the system is idle in both cases, power usage should be the same, if not, there is something going on.

(mehr…)

ldapsearch and base64 encoding November 3, 2009

Posted by lurchi in Computer.
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ldapsearch is a very nice tool, but there is one small problem — if an attributes value contains any special characters (anything outside the range of printable ASCII characters), the value is base64 encoded.

so for
ldapsearch -x -h abook.rwth-aachen.de -LLL -b o=abook sn='brüns' cn
the results are:
dn: uid=Stefan.Bruens@rwth-aachen.de, ou=datenbank, o=abook
cn:: U3RlZmFuIEJyw7xucw==

the following snippet helps:
alias un64='awk '\''BEGIN{FS=":: ";c="base64 -d"}{if(/\w+:: /) {print $2 |& c; close(c,"to"); c |& getline $2; close(c); printf("%s:: \"%s\"\n", $1, $2); next} print $0 }'\'''

Results:
ldapsearch -x -h abook.rwth-aachen.de -LLL -b o=abook sn='brüns' cn | un64
dn: uid=Stefan.Bruens@rwth-aachen.de, ou=datenbank, o=abook
cn:: "Stefan Brüns"

Warning: Of course this works for attributes with printable characters only. LDAP can contain binary data, e.g. images of the user in JPEG format.

VMware and 3D acceleration on Intel graphics Dezember 2, 2008

Posted by lurchi in Computer, Graphics.
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After this blog has been dead for about two years, I will start with some technical stuff – at least when computers don’t work as expected, most times I know how to fix it.

Ok, lets move on to the topic of this post. Short time ago I was forced to do some stuff on windows again (EEKK — the word registration number still sends me cold shivers …). As I needed really working USB support (unfortunately Nokia thinks Linux is good enough for their hardware, but not for their customers computers), and I was unable to make it work neither in Xen (not at all) nor with KVM (unusably slow), I ended up with VMWare.

So, USB worked really nice, no problems at all. While I was there, I thought “let’s have a look at the 3D acceleration”. At a first glance, it looked quite easy – “upgraded” the VMs version to 6.5, and ticked the option for “3D acceleration” – TADA – “Failed to construct 3-D rendering backend. The 3-D features of the display card will be disabled.”

Ok, what’s wrong? After some digging in the log, I found these two suspicious lines:
mks| GLUtil_InstallExtensionLists: Missing required extension GL_EXT_texture_compression_s3tc
mks| GLUtil_InstallExtensionLists: Missing required extension GL_EXT_framebuffer_object

Unfortunately, the Intel driver does not support these two OpenGL extensions – more or less.

Let’s have a deeper look into this. First, S3 texture compression. S3TC is a lossy texture compression used in many games, and it is mandatory for DirectX. Unfortunately, S3TC is covered by some patents, and although the decompression is handled by the hardware, a conformant OpenGL driver has to handle decompression and compression. As in many cases (most games ship with precompressed textures) only decompression is needed, which is handled by the hardware, there is a switch to force Mesa to report support of S3TC although it actually only handles one half – if you want to know more, force_s3tc_enable drirc are the keywords.

If you want to know more, or even want to enable compression as well, have a look at Roland Scheideggers’ page.
As said, S3TC is covered by patents, so enabling compression is legally problematic. But there may be some hope, as S3TC is “owned” by VIA, and they recently open sourced their Linux graphics driver, maybe we will even get S3TC out of that – at least, they could put compression under a liberal license, and still sell licenses to ATI/Nvidia/Intel (I still may have some dreams, don’t I?)

The other part is GL_EXT_framebuffer_object, shortly referred to as FBOs. These are really not supported by the Intel driver at the moment, but there the new memory managers come to the rescue, see this post.

Summarized, as soon as GEM has landed in the kernel tree (and/or in the downstream distributions), it should be possible to make it work. GEM should be available soon™, and S3TC can be worked around today.

Finally … September 18, 2006

Posted by lurchi in Australien, Unterwegs.
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Momentan sitzen Nils und ich vor unserem Campervan, haben gerade Kaffee getrunken und Kuchen gegessen, und vertreiben uns unsere Zeit mit Bloggen, Photos bearbeiten und ausruhen – wie gut, dass der Campingplatz einen herrlichen Swimmingpool hat, der ungefähr 30 Meter von unserem Platz entfernt ist. (mehr…)

Goodbye and thanks for the fish! September 11, 2006

Posted by lurchi in Australien, Unterwegs.
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1460km und 7 Breitengrade – es wird immer wärmer und immer menschenleerer.

Nach einem kurzen Abstecher zum Hawks Head haben wir Kalbarri mittlerweile hinter uns gelassen, auch der François Péron National Park ist 320km von uns entfernt, und in einer halben Stunde geht es weiter zum Ningaloo Reef, wir haben also schon einiges hinter uns (mehr…)

Goodbye Perth! September 4, 2006

Posted by lurchi in Unterwegs.
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Es ist geschafft – das Praktikum beendet, der Bericht geschrieben, und Perth liegt mittlerweile 500km südlich.

Los ging es am Freitag mittag, Nils (Aachener Etechniker und ebenfalls Praktikant am Watri) und ich haben uns einen Campervan gemietet um damit für die nächsten drei Wochen Australiens Südwesten zu erkunden.
(mehr…)

Nachricht aus Down Under März 13, 2006

Posted by lurchi in Australien, Unterwegs.
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Nachdem ich mittlerweile seit mehr als zwei Wochen aus Aachen weg bin und seit gut einer Woche in Australien, kommt an dieser Stelle meiner erster Bericht aus meiner neuen Heimat. Da sich seitdem doch einiges ereignet hat, und ich zwischendurch nicht zum schreiben gekommen bin, ist dieser etwas länger. In Zukunft werde ich dann hoffentlich etwas häufiger und dafür kürzer schreiben. (mehr…)

In the beginning there was void … März 11, 2006

Posted by lurchi in Australien, Uncategorized.
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So, this is my first post to this blog. As I may also write about some topics which are for a larger audience, especially everything related to my commitment with open source software, this first post is in English only. Main topic on this blog will be my stay in Australia (at least for the next few month), and as these posts are targeted at my family and friends back home in Germany, I will write them in german. Sorry for any inconvenience ;-)

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