Saturday, December 17, 2011

kdepimlibs-4.7.3 imap4 regression fix

Attention Gentoo users: If you're running kmail- and kde-4.7.3, and if you have been hit by bug 382411 (problems with local filters, cannot upload unread message on imap; see also here and here), please keyword kde-base/kdepimlibs-4.7.3-r1 and give it a try. (You may want to log out and log back in.) This upgrade seems to fix the problem... If I get some positive feedback, I'll fast-track it for stabilization. Cheers!

Friday, December 9, 2011

Unit tests - a useful thing causing occasional pain

For whoever has never heard that expression, unit tests are a way to test the functionality of a program or library in an automated way, by for example checking the evaluation result of test data. This is a great thing and can help massively in identifying coding mistakes. CMake provides a mechanism, and in many KDE packages test routines are included.
So far, so good, this is the theory, now let's look at reality. In Gentoo, the main KDE distribution is split into 295 (!) packages. Many dont have any tests (oxygen-icons comes to my mind as a nice example). Of those that have, 37 now have all the test routines hard disabled, and I guess a few are missing that I still have to add to the list. Why? Well, first of all, you have to know that compilation usually runs in Gentoo as an unprivileged user detached from any graphical desktop session, and this user also runs the test routines. In addition, tests should also run fine "offline", i.e. without internet connection. One of our developers is running a great thing called a "tinderbox", where build and unit tests in various configurations are automated- in an isolated environment, and possibly even without network access. So, what can go wrong?
  • The tests need X11. Well, actually we can get around this, with a nice hack called virtualx. A background framebuffer X server is started for the test phase only, and the tests are redirected to that display. Works even sometimes. :o)
  • The tests need a dbus session bus. I think we could get around this too, but nobody bothered to do it so far and I'm not a dbus expert. 
  • The tests need an entire KDE desktop to interact with. Yes, that happens, and unfortunately, we have to disable them in this case, see above. 
  • The tests try to download a data set from, say, IMDB, CDDB, or similar. Bad, bad, bad, see above.
  • Next, the tests pop up dialog boxes asking for user interaction. A window asking for a GnuPG passphrase is my personal favourite... 
  • And last, what I particularly like is a unit test that fails... and after digging into the test log, I see a fat comment "This does not work yet and needs to be fixed!"
I guess at least part of the above points is a matter of policy. Test routines requiring user interaction can provide valid information, but of course they are not particularly useful for automated testing... Anyway...

PS. This blog post took slightly longer to write since a libreoffice-3.5 build in the background went berserk... load 65, >180 concurrent compilers... :D

Wednesday, December 7, 2011

Gentoo KDE 4.7.3 going stable now... including KDEPIM

Another KDE version stabilized in Gentoo... x86 is done with KDE 4.7.3 since this morning, amd64 is following right now. For those of you who don't read Portage news items, here's again my message about KDEPIM:
The stable upgrade from KDEPIM to KDEPIM 4.7.3 is a MAJOR upgrade with potential for major breakage. Therefore we will try to keep and support the old, so-far stable KDEPIM as long as possible.
If you don't want to upgrade your KDEPIM yet but keep the old version, please download this mask file and add it into your /etc/portage/package.mask.
If you decide to upgrade, please have a look at the upgrade guide first.
In addition there have been a few reports of problems with the Plasma desktop after upgrade. Usually these are caused by single plasmoids malfunctioning, so what should help is to remove some of the plasmoids from your desktop and add them again... Otherwise the upgrade from 4.6 to 4.7 should be pretty much unproblematic, and bring you a shiny new desktop with quite some new features.
With the new KDE we have finally also been able to stabilize a newer version of digikam and kipi-plugins (both at 2.3.0 now!), and also rekonq gets a big bump to version 0.8.0, which should fix an overdue security bug.
Finally and not related to the stabilization, since yesterday we have a package in the main tree that provides integration of Google calendars / contacts into Akonadi: kde-misc/akonadi-google ... It's a bit experimental still and also not an official release but a packaged snapshot, but anyway, if you are interested, give it a try!

Monday, November 14, 2011

The Regensburg nanotube team is growing!

A lot of things have happened recently in our nanotube / nanomechanics research group in Regensburg... First of all, I'd like to congratulate Peter Stiller for finishing off his Diploma thesis and thereby his degree. Peter is immediately continuing as a PhD student, however switching topic from nanomechanics to charge qubits in carbon nanotubes - a newly founded project in the SFB 631. Here we plan to couple electronic quantum states in carbon nanotube double quantum dots to the electric field of a coplanar microwave resonator.
Then, straight from München and the research group of Jan von Delft, Alois Dirnaichner will join us soon as PhD student to work on experimental and theoretical characterization of few-electron states in ultraclean suspended carbon nanotubes. This is a project pursued together with the groups of Milena Grifoni and Christoph Strunk; we hope that the high quality of our carbon nanotubes enables us to do fundamental observations and analysis on unperturbed electronic multi-particle states.
Next, Sabine Kugler joins the nanomechanics team for her MSc thesis project. She will continue the development of chip geometries and materials suitable for combining carbon nanotubes with complex electronics, and help us with the characterization measurements.
Finally, last but not least, Hermann Kraus starts in december as a Diploma student, and will focus on high-frequency electronics at very low temperatures and superconducting nanocircuitry. Time to get these electrons rock'n'roll!

Real online dilfridge :)

By the way, I just found out there's a real dilfridge (dilution refrigerator) live on twitter... :) Would be interesting to know which research group that is. With the hard-soldered caps on the top IVC plate and the ribbon cables this is for sure an Oxford Instruments model, but whatever else is visible in the lab looks like pretty standard equipment...

Sunday, November 13, 2011

KDE 4.7.3 - Identifying Plasma crashes with Gentoo

One of the less pleasant surprises about KDE 4.7.3 was that somehow "upstream" managed to introduce quite some stability regressions in the Plasma desktop. On both my laptop and my work desktop it kept crashing every now and then. This usually does not cause big problems as Plasma is immediately restarted by some KDE magic, however it can be quite annoying (in the British sense). Which is why by now we have kde-base/plasma-workspace-4.7.3-r2 in the Gentoo portage tree, where the worst offenders should be fixed by backporting from future 4.7.4. Please upgrade and test...
A related question is of course, if Plasma crashes, how do I get any more information on the origin of the problem? Usually the KDE crash reporter DrKonqui does not pop up... For diagnosis, you'll have to enable debug info while building, and core dumps while running the software. For doing both in Gentoo we have an excellent howto, which also documents how you use gdb to extract the backtrace information. Then, if you report the bug, please paste the backtrace; only that makes it possible to identify the exact problem that caused the crash! Happy hunting!

Sunday, November 6, 2011

Gentoo KDE stabilization and the KDE overlay

Here's two small news items that may be worth your attention.
First of all, we (as the Gentoo KDE team) have to decided to change our stabilization target from 4.7.2 to 4.7.3 - the main reason being that there have been many stability improvements e.g. in KDEPIM. This also means that for now the stabilization process is on hold, since version 4.7.3 needs some time to "ripen on the tree". Anyway, feel free to grab the stabilization list from bug 388279 and try it out. Most likely the list will still be updated a few times for minor fixes.
Second, if you are using the Gentoo KDE overlay, it has now been migrated to so-called thin manifests. This makes using git way easier for us committers. You as a user will however need sys-apps/portage from ~arch, because the current stable version does not support the new Manifest file format yet. This may sound like a dangerous requirement, but actually most the devs use testing portage and do not encounter any big problems. I'm running sys-apps/portage- here and all is fine.

Sunday, October 30, 2011

Preparing another Gentoo KDE stable upgrade: KDE 4.7.2

With the blessing of the Gentoo KDE team, I have recently filed the request for stabilization of KDE 4.7.2, which means Gentoo stable users will see the upgrade sometime in the coming weeks, after the testing and the resulting bugfixing has completed.
In general the upgrade from 4.6.5 to 4.7.2 should be easy and bring quite some advantages; we're really happy with most of KDE 4.7.2 here. In particular also many quirks of the graphics acceleration have been ironed out.
However, there is one Big Thing happening with the upgrade: While the stable version of the KDE PIM applications (kontact, kmail, korganizer, ...) so far was still, we will try to stabilize KDE PIM 4.7.2 now. (Not my idea.) This is a major upgrade with potential for major breakage, especially since many people think that KDE PIM 4.7.2 has not even reached beta quality yet.
Why are we doing this, you may ask? Well, the big problem is, the upstream KDE PIM developers consider version obsolete and unsupported. The first regression has appeared (see Gentoo bug 382411 and KDE bug 279432), and we expect there will be more in the future. We will keep KDE PIM in Gentoo and try to support it as long as we can, but then we're not familiar with the code and cannot do too much on our own if things start to break.
Anyway. If you're brave and want to help us testing, please grab the list attached to the stable request, place it on your Gentoo system into /etc/portage/package.keywords, and upgrade your system.
  • If you want to upgrade the rest of KDE but not KDE PIM, grab the corresponding mask file and place it into /etc/portage/package.mask. This means all KDE PIM applications will remain at trusty version until you remove the mask entries again.
  • If you want to upgrade the entire KDE including KDE PIM to version 4.7.2, please read the KDE PIM upgrade guide in our new Wiki first. And yes, please feel free to contribute improvements there!
We're looking forward to hearing about your experiences, and if you encounter problems, please file bugs on our Gentoo bugzilla!

Saturday, October 29, 2011

Towards Calligra 2.4

I've just committed the ebuild for Calligra 2.4 beta 3, i.e. in Gentoo app-office/calligra-2.3.83, to the portage tree. If all goes well this is going to be the last beta version before Calligra 2.4, the first release of the fork (or should I better say, successor) of KOffice. So, get your penguins compiling and give it a try, for a last big round of bugfixing!

Sunday, September 25, 2011

Poll: KDEPIM 4.7 - ready for you?

If you have read my previous post, you will already suspect that we may not be able to support the "old" KDE PIM applications (i.e. kdepim-4.4; the KDE PIM main applications are akregator, blogilo, kleopatra, kmail, knode, knotes, kontact, korganizer, ktimetracker) much longer. Problem is, most data on the usefulness and stability of new Akonadi-based KDE PIM (i.e. kdepim-4.7) is just based on anecdotes. So, to get at least some half-way representative numbers, here's a poll for you. As Gentoo has been offering the new software version all from the start, please tell me your opinion on the new KDE PIM (click on this link if the poll does not show up):

Thanks a lot in advance!

Who cares about users and distributions anyway?

As distribution developer, some of our most important tasks are
  • making packages work together nicely
  • and selecting "stable" package version sets for a broader audience
On the whole, this is appreciated also by "upstream", i.e. the software authors and the development communities. Every now and then, however, things just become slightly crazy, leading first to frustrated Gentoo devs, then to a lot of frustrated users.
  • Bad example number 1: Amarok.  Do you still remember the note that "you may lose your database on stable upgrade from KDE 4.4 to KDE 4.6" in the KDE 4.6 upgrade guide? Well, that note was the end result of quite some discussion, and (at least as far as I know) Debian stable users ended up with the same database mess. So what actually happened here? Simple, KDE 4.4 was for the Amarok developers so far in the past that they did not even consider an upgrade path. Every complaint that the upgrade was broken got a boilerplate response "The problem is fixed in the new version", although what upstream actually understood as fix (and may indeed have been an improvement) introduced the upgrade trouble in the first place...
  • Bad example number 2: KDEPIM. Right now there are very different opinions on whether Akonadi-based KDEPIM-4.7 is already ripe for mass consumption. Well, you'd say, if there are any doubts about that, how about at least fixing regressions and keeping KDEPIM-4.4 in a working state for a bit more time? Alas, the old version is now officially declared unmaintained, and the first bad regression has appeared with KDE-4.7.1. Discussion on IRC with one of the KDEPIM developers led me to this exchange...
    [12:42:12] <dilfridge> xxxx: re bug 279432 - please, please reconsider and have at least a look at it... we still have users with a lot of problems with kmail2, and it would be great if we could support kmail1 / 2  in parallel for a while
    [12:42:12] <bugbot> KDE bug 279432 in kontact (mail) "Error while uploading message (unexpected end of data) when applying filters" [Normal,Resolved: unmaintained]
    [12:44:01] <dilfridge> I can help testing since I see the problem myself
    [13:30:29] <xxxx> dilfridge: you can help by writting a patch for it
    [13:30:58] <dilfridge> indeed, I can... problem is that I'm not familiar at all with the code
    [13:32:09] <dilfridge> I would not even know what parts are interacting there... kdepimlibs, kioslaves...
    [13:40:31] <xxxx> note that using online imap with kmail1 never worked correctly
    [16:22:02] <dilfridge> xxxx: maybe, but I've never used online imap and have the same problem :|
    [end of conversation]
    I talked to a colleague about that and got the response that in addition to focussing on KDEPIM-4.7, "the KDEPIM guys are now paid for doing the mobile version, desktop comes second". WHAT? Something's seriously warping priorities here, I mean, I like to sometimes check my e-mail with my mobile, but without a working desktop mail application I would probably not even have an e-mail account!
Summary of all this rant: If you're an upstream developer, please remember that what you consider stable is probably not the most conservative, end user-friendly estimation. People are using older versions, distributions are packaging older, "ripened" versions, and also these need some minimum support and upgrade paths! Otherwise, your users might just go away...

Thursday, September 1, 2011

PhD position available: Transport spectroscopy and theoretical analysis of few-carrier systems in carbon nanotubes

We're currently planning a research project in close collaboration with the theory group Prof. M. Grifoni, with working title "Transport spectroscopy and theoretical analysis of interacting few-carrier systems in semiconducting and small-bandgap carbon nanotubes". It combines equal parts of experimental work and theoretical data analysis and modelling. You've already done an excellent solid-state physics theory Diploma or MSc thesis and liked it, but would like to get your hands dirty as well? Then you're maybe the perfect candidate!

Interested? Please have a look at the PDF file with more details, at our web pages (group Prof. M. Grifoni, group Prof. C. Strunk, group Dr. A. K. Hüttel), and contact Andreas K. Hüttel (e-mail: for more information!

PRL accepted: Universality of the Kondo effect in quantum dots with ferromagnetic leads

I'm very glad to be able to report that our manuscript "Universality of the Kondo effect in quantum dots with ferromagnetic leads", describing results that we've been working on during the last months, was just accepted for publication in  Physical Review Letters.
So what is it about, in a few simple words?
In general, much of our work is about charges trapped inside carbon nanotubes at very low temperatures (0.05K). Such a trap for e.g. electrons is called a quantum dot; similar to the electron shell of an atom or molecule, the laws of quantum mechanics force the electrons to occupy specific discrete levels, or quantum states. By looking at a tiny tunnel current through a quantum dot we can characterize its quantum mechanical properties; this is called transport spectroscopy.
The Kondo effect is a special case, as it is caused by strong interaction between localized charges inside the quantum dot and charges in the leads that we attach to the quantum dot. Whenever the localized charge can assume either of two (or more) states with equal energy ("degenerate states") and these states all couple to the leads, the Kondo effect causes an extra electrical conductance through the system. This is one of the simplest many particle effects in quantum mechanics and has fascinated researchers for quite some time; its behaviour is called universal, as it is independent of many detailed properties of the system at hand. In a non-magnetic system, the degenerate states are usually given by different directions of the electron internal magnetic moment, its spin.
Now, we contact our nanotube quantum dot with magnetic contacts. In these contacts, 1) the different directions of spin can couple differently to the quantum dot, and 2) the number of charges with one spin direction differs from the other (that's just what makes them magnetic). Among other things, we've been able to show that all this modification just acts on the Kondo effect the same way as an (imagined) magnetic field, so by applying the reverse magnetic field with an external magnet coil, we can restore the universal behaviour as known from non-magnetic systems. This makes the system much easier to describe, and will, we hope, be useful for future work in spintronics, where the magnetic moments are to be used for information processing.

"Universality of the Kondo effect in quantum dots with ferromagnetic leads"
M. Gaass, A. K. Hüttel, K. Kang, I. Weymann, J. von Delft, and Ch. Strunk
accepted for publication by Physical Review Letters; arXiv:1104.5699 (PDF)

Note: the Wikipedia articles "quantum dot" and "Kondo effect" are not wrong, but describe special uses of these terms and not the most general case as known today. Unfortunately this makes them completely useless as references here...

Sunday, August 21, 2011

A sci-fi novel re-read: "Limit"

The first decade of the new millennium has brought on multitudes of changes. The proof-of-concept of a working He3 fusion reactor, although revolutionary in itself, would not have shaken the world. In combination with the completion of a functional space elevator and the start of large scale automated mining operations on the moon, however, politics and the world economy enter turmoil. Now, Orley Enterprises, the multinational behind both breakthroughs, is about to celebrate the opening of two luxury resorts- one on the already well-established OSS ("Orley Space Station"), the other on the moon itself. A selection of celebrities, inventors, and investors gets a first glimpse, from a Hollywood actor famous for playing Kurt Cobain and Perry Rhodan, America's First Talklady, a Russian oligarch, the Hong Kong owner of Luis Vuitton and a dozen other fashion labels, all the way to the researcher famous for recent breakthroughs in stem cell technology. At the same time, a private investigator in Shanghai is asked to look into the disappearance of a friend's employee, who turns out to be one of the dissidents that the Chinese government has not been able to locate for years. When he finds first traces of her, however, events turn unexpectedly violent...
Most of the novels I've been reading throughout the last years were written in English, which is maybe the reason why some of the dialogues seemed a bit strange to me. In addition you sometimes notice that the book is already a few years old, eg. when - as historical backdrop - "the USA turned Green during the presidency of Obama". However, on the whole the setting is for a sci-fi novel comparatively sound, the story is gripping with nice suprises all over the way, and the author gets the athmosphere definitively right...
Frank Schätzing, "Limit". Sci-fi thriller about corporate espionage, the first-ever hotel on the moon, and a changing world. 4 out of 5 carbon nanotubes in the near-future sci-fi category. German. Unfortunately, no English translation yet (but there's Italian, Spanish, and Danish already).

Sunday, August 14, 2011

MSc / Diploma research projects available

We're at the moment looking for clever candidates for two Diploma / MSc projects in the nanotube transport and nanomechanics group Regensburg:

In both cases, you will work in close cooperation with colleagues from several carbon nanotube projects. Contact Andreas K. Hüttel (e-mail: if you're interested! Regensburg students only, sorry!

Saturday, August 13, 2011

Feeling underlinked?

Diego's flood of tinderbox underlinking bugs kept me puzzled in the beginning, because one thing I don't want to do is replace the linker on all my systems with some piece of half-experimental code. Luckily, after some discussion with him on IRC it became clear that many of the issues discovered by using gold can also be found using the --no-add-needed option of the normal linker. However, it has to be forced in the gcc profile to really make sure that it is applied.
So, if you want to make your system sensitive to most underlinking issues, run the following script (closely based on Diego's forced-as-needed instructions) as root. It will create an additional gcc profile, which you can then choose with eselect... Happy bugfixing.

export SPECSFILE=$(dirname "$(gcc -print-libgcc-file-name)")/forced.specs
export CURRPROFILE=/etc/env.d/gcc/$(gcc-config -c)
gcc -dumpspecs | sed -e '/link:/,+1 s:--eh-frame-hdr:\0 --as-needed --no-add-needed:' > "$SPECSFILE"

Friday, July 29, 2011

KDE-4.7, Digikam 2.0.0, KIPI-Plugins 2.0.0

Another year, another major KDE release - KDE 4.7.0 is out and already in the portage tree for your consumption. So far I can recommend the update very much- it seems like this time there is no "zero version effect" and 4.7 is working nicely from the start. With one caveat however: I've been staying with the old KDEPIM-4.4 so far, as I've heard mixed reports about the new KDEPIM version included in 4.7.
If you want to combine KDE-4.7 with KDEPIM-4.4, you can do that as well: get the mask file and place it in your /etc/portage/package.mask. If you are using the full-kde meta ebuild kde-base/kde-meta, enable the useflag "oldpim" there, so dependencies on the KDEPIM version are relaxed. Afterwards you can update your KDE to version 4.7.0, and KDEPIM remains at trusty version
Using KDE-4.7 has a very nice side effect: you can upgrade Digikam and KIPI-Plugins to version 2.0.0, also just released, with a ton of new features. Enjoy!
Thanks go to Jorge Vicetto and Alexey Shvetsov, who put the most work into preparing the new ebuilds and testing betas and release candidates. After all this effort, updating to 4.7.0 immediately went very smooth!

Sunday, July 17, 2011

Vacation reading: "Sewer, gas, electric"

... He stood on the Yabba-Dabba-Doo's launch deck, wearing a star-and-moon-speckled wizard's hat and a set of fake-nose-and-moustache glasses. "Hey world, time for another visit from Mr. Science. Today we're going to do an experiment in kinetic energy transfer. This" - he pointed to a long cylindrical track that had risen out of the hull beside him - "is an electromagnetic rail gun, a scaled-down model of the very same device the Republicans are using the protect the White House from a nuclear attack. And this" - he held up a hefty deli sausage - "is twenty pounds of kosher salami. Now what we're going to do is accelerate the salami to Mach 9 and see what happens to the bow of that ship over there, OK? Kids, please don't try this at home without your parents' supervision ..."
Every now and then, a really bizarre book is needed. So, when I saw another obscure trilogy-of-something on the bookshelf, I gave it a try. After all, I've survived Pynchon's "Gravity's Rainbow" (which a friend gave me as a present many years ago; she's now a professor of comparative literature studies). And so we enter the strange world of 2023, where ecoterrorist and pirate Philo Dufresne plays practical jokes on large corporations with his green-with-pink-polka-dots submarine, robots have become everyone's best helper, the New York sewers form a highly mutagenic biosphere including the giant white shark Meisterbräu, and the shadows of Disney and Hoover loom. A murder mystery has to be solved, which requires all the attention of Joan Fine, ex-wife of America's richest entrepreneur and ex-employee of the sewers department after her first encounter with Meisterbräu (the hand grenade blew up half of Times Square and ignited the Hudson River)...
What shall I say. It was interesting reading, but I'm not really sure if I will read it again. Some clever ideas, good jokes and nice discussion. In the end, what drove me off was my personal feeling that the crazyness and style could not keep up with the storyline. Which is a really hard-to-reach objective, as even Douglas Adams may concede from above; while focussing the attention of the reader requires at least some sort of coherent narrative, the innovative character of the text also needs culmination and finesse. (Maybe, just maybe, all the fake Ayn Rand dialogues got on my nerves, too.)
Matt Ruff, "Sewer, gas, electric: The public works trilogy". Aspect 1998; ISBN 044660642. Two-point-three-three-three-three out of of five eyes in the pyramid in the category "whacky conspiracy theory postmodernism". May be considered quite bad taste (but that's likely true of many books in this genre).

Saturday, July 16, 2011

Having fun with Hugin

There's as always a lot of fun stuff you can do with Gentoo; what I've discovered recently is Hugin (media-gfx/hugin) for panorama stitching. See the above image (and in particular click on it for a better view!) for one of the amazing results. The file is not really perfect yet and probably will never be, as boats tend to move with the waves. Even after removing all useless alignment points and adding many correct ones manually, if you look very closely there are some shifts. Nevertheless, I think the result is pretty neat. The image is assembled from 16 separate free-hand portrait photographs, each with resolution 3456 x 2304; after cropping the total size of the assembled image is 20227 x 1390.

Arry Potter et les Reliques de la Mort, 2e partie

This is already the second time I'm watching a new Harry Potter movie while in France, but the first time that it's in French. :) Ah well, Collioure is not Paris, but breathtakingly beautiful anyway, also now at night with the full moon over the bay and the castle... But I disgress...
As expected, not counting all the moms and dads in the audience, I was somewhere at the upper age edge. Accordingly, the movie makers had also obviously put a lot of effort into making all the killing in volume 7 more "boom bang crash" but not really that bloody. Still, the whole experience was quite some action and special effects spectacular, keeping (as far as I can remember now, having stuffed my head with all that physics in the meantime) rather close to the book. The lightheaded humour sprinkled through some of the earlier movies was mostly missing, but that was to be expected. The bad guy is finished off heroically, with quite some tragic losses and tears shed on the way, and finally all the Dumbledore / Snape connections become clear. (By the way, in the French version the name Snape has been translated... seems like some someone actually realized that JKR is good on wordplay.)
On the whole I liked this Harry Potter movie more than many of the other more recent ones, mainly because there was enough "movie time per book page" to tell a coherent story. If you have read the books a few times, that probably does not matter, but there might also be some moviegoers who have not... There even was enough time to add the cheesy "19 years later" epilogue, causing quite some sniffing in the audience. I felt that our heroes did not look old enough there, just dressed up a bit different ("adult style"). But then, maybe I'm just too old and you have to be sixteen to notice the change in makeup...
Now of course the most interesting question is, how will J. K. Rowling continue. From a financial point of view, giving up the franchise at this point would of course be sheer stupidity; even so, I understand that some sort of a break might be needed. I'm not a sufficiently enthusiastic fan to follow all the internet fandom and rumour sites, but in the long run, I believe that some more books will turn up for sure. After all, life does not end after highschool, even if you have just overcome le Seigneur des Ténèbres, right? :)

Wednesday, July 6, 2011

Near most-beautiful: La Seu d'Urgell cathedral

Ever since I picked a related topic for one of my highscool final exam in history, I have been a big fan of Romanesque architecture, churches and masonry in general. For those who don't know, this term denotes a period rougly 1000 A.D. to 1300 A.D.; wikipedia of course has an extensive article on the subject. The largest and most elaborate Romanesque cathedral ever unfortunately has been torn down many centuries ago and exists today only in digital reconstruction, but in spite of the age quite some buildings have survived until today. So far my clear favourite was the church of Fontevraud-l'Abbaye, an incredibly light building of clear lines, famous also because King Richard Lionheart is buried there. Since today, I have a clear runner-up: the cathedral of La Seu d'Urgell in Catalonia, whose bishop is one of the co-rulers of the Principality of Andorra. The pictures on the wikipedia page (and also my own ones) do not do the building justice. It is at the same time both beautiful with clean lines and elegant architecture and dotted with the obscure, partially bizarre or funny detail masonry that comes up on some of the more elaborate buildings of that era. Beyond describing in words!

Thursday, June 30, 2011

Carcassonne, the city from another world

Carcassonne just had to be the first stop of my summer vacation. After reading about it in books both fictional and nonfictional and seeing one picture of the cite I was hooked. What a place this is... The 19th century restoration of the fortress definitively paid off, and a "medieval city/fortress spirit" is captured despite the hordes of tourists passing through the place every day. Then, of course, this is a place mostly for tourists today, albeit an amazingly beautiful one. Seen from the river Aude the ancient city seems to be floating high up in the sky... and close up the fortifications are overwhelming. Already looking forward to postprocess the photographs later at home... :)

Vacation reading: "Young Miles"

I'm on vacation... and while that often means I'm running around from romanesque monastery to roman rubble pile, this time it's also a real relaxation vacation. Including beaches and many shady cafes in beautiful old cities (have I mentioned Carassonne already?). Time to slow down, go through the recommendations from friends collected throughout the last months and grab a good book (or two, or three). I started of with "Young Miles", and what a strange start it was...
"It isn't easy, being a Vor lord..." Miles Vorkosigan, age 17, is only son of the emperor's regent and heir to an ancient title himself. Life could be perfect, were it not for that unfortunate assassination attempt on his parents years ago, which left him, err, vertically challenged for life, and with rather brittle bones. When your predestined career is the military, this does not really help... especially if you fail the entrance physical by breaking both legs at the first hurdle of the obstacle course. This, however, is where the story only starts. Our hero is gifted with ego, brains, and a not-just-slightly hyper attitude to bounce from one improbable situation into the next, collecting friends, allies, enemies, and a most crazy storyline. Of course, his adventures include all the things that real academy cadets are told never to expect (even in imperial security, you'll only ever meet ugly male spies), and the chain of command is not really a suitable concept for a little egomaniac like Miles. Kept me laughing for quite some time, and I will have a look at the many already existing sequels sometime soon.
A friend recommended the book to me with the words "like Tyrion Lannister from Game of Thrones, with less daddy issues and prostitutes", but that comparison is missing a few points. Not as deep as Game of Thrones and not as elaborate, but very much fun relaxation reading. It's a bit like going from Lord of the Rings to the early, light-hearted Harry Potters, and mixing in a dose of Stephanie Plum... :) Oh yeah, and don't get turned off by the book cover. Other people find it strange too and have made way better suggestions...
Lois McMaster Bujold, "Young Miles". Baen Books 2003; ISBN 0-7434-3616-4. Buffo space opera, screwball sci-fi comedy. 4 out of 5 smileys in the Light Reading category :))))!

Saturday, June 18, 2011

A "new" CUPS is coming your way...

It's taken some time, but finally CUPS-1.4, a "new" major release of "the standards-based, open source printing system developed by Apple Inc. for Mac OS® X and other UNIX®-like operating systems", will be arriving for our stable users in the near future. The arch teams are testing, see bug 333781 for the details and progress.
So what does that mean? Well, technically there are a lot of new features since CUPS-1.3. In practice, I hope that some of the ancient Gentoo bugs like #341127 or #349496 go away now, since finally CUPS supports some of the features that modern desktop environments require. Also, right now CUPS is an embarrassing security hole, which will also be fixed by the upgrade.
In the version about to be stabilized, we do not support the new libusb-based interface for USB printers yet. Accessing USB printers will be done via the USB printer functionality in the kernel, as in CUPS-1.3. Why? Simply because there are still way too many problems with it. If you want to give it a try anyway, just keyword net-print/cups-1.4.6-r21 - the only difference between -r2 (the stable candidate) and -r21 is that -r21 supports the libusb backend with the usb use-flag. Cheers!

Friday, June 3, 2011

NI-VISA final fail

In a previous blog post, I already pointed out that using the NI-VISA library to control lab devices with Linux is becoming more and more painful - especially when you heavily rely on National Instrument's high speed USB-GPIB adapters. But hey, supporting kernels newer than 2.6.24 is luxury anyway, right?
Yesterday I tried to update my "test box" for Linux lab software, just in case I can maybe convince one of my colleagues to work with that strange OS for a change. Then, I realized that for us the NI-VISA package has finally become totally useless:
(meas) pc5xxxx ~ # emerge -uDNav --keep-going world

Performing Global Updates:
(Could take a couple of minutes if you have a lot of binary packages.)
  .='update pass'  *='binary update'  #='/var/db update'  @='/var/db move'
  s='/var/db SLOT move'  %='binary move'  S='binary SLOT move'
  p='update /etc/portage/package.*'

These are the packages that would be merged, in order:

Calculating dependencies... done!

!!! All ebuilds that could satisfy ">=sys-fs/udev-151[extras]" have been masked.
!!! One of the following masked packages is required to complete your request:
- sys-fs/udev-9999 (masked by: package.mask, missing keyword)
- sys-fs/udev-168-r2 (masked by: package.mask, ~x86 keyword)
- sys-fs/udev-168-r1 (masked by: package.mask, ~x86 keyword)
- sys-fs/udev-168 (masked by: package.mask, ~x86 keyword)
- sys-fs/udev-167-r1 (masked by: package.mask, ~x86 keyword)
- sys-fs/udev-167 (masked by: package.mask, ~x86 keyword)
- sys-fs/udev-164-r2 (masked by: package.mask, ~x86 keyword)
- sys-fs/udev-164-r1 (masked by: package.mask, ~x86 keyword)
- sys-fs/udev-164 (masked by: package.mask, ~x86 keyword)
- sys-fs/udev-163 (masked by: package.mask, ~x86 keyword)
- sys-fs/udev-162 (masked by: package.mask, ~x86 keyword)
- sys-fs/udev-151-r4 (masked by: package.mask)

(dependency required by "sys-power/upower-0.9.9" [ebuild])
(dependency required by "kde-base/kdelibs-4.6.2-r3" [ebuild])
(dependency required by "kde-base/khelpcenter-4.6.2" [ebuild])
For more information, see the MASKED PACKAGES section in the emerge
man page or refer to the Gentoo Handbook.

(meas) pc5xxxx ~ #

The age-old kernel requires old udev (<=142 if I remember correctly), which I enforced with a package.mask and now is incompatible with other recent stuff. Ah well... >:| no more VISA on Linux for us.

Tuesday, May 17, 2011

A letter for a lot of money

Starting up a new experimental physics research group is again and again interesting. Last time I was really nervous was when I for the first time signed the paperwork to hire someone (in case you're from the US, in Germany and many other European countries PhD students are in the sciences paid employees). Today, another lengthy process came to its (momentary) conclusion; I'll have however to explain this a bit.
Our research is focussing on electronic and mechanical processes at extremely low temperatures. "Extremely low" means in that case something like 20mK, or 0.02 degrees above absolute zero, or -272.95°C. To reach such temperatures, several steps of cooling have to be employed. First, the entire experimental assembly is submerged in a dewar (something like a thermos flask) filled with liquid helium, boiling away at 4.2K. Then, inside another vacuum chamber, evaporation cooling with again liquid helium is used to lower the temperature even further to somewhere around 1.5K. Lastly a closed cooling cycle with a mixture of the two isotopes of helium, helium-3 and helium-4, is used to lower the temperature even further to the base temperature of 0.02K. This entire machinery is called a dilution refrigerator; it was invented in 1951, and is by now available commercially from several companies worldwide.
So what happened today? Well, after getting a grant for buying one of them beasties, writing up the specifications, starting the Europe-wide call for tenders, awaiting and carefully evaluating the quotes, finally I've sent off the decision letter. "Please buy this one." Phew. I hope all works out, this thing costs about as much as a top-range Ferrari...

Saturday, May 14, 2011

Hunting the glib-networking / libproxy mystery bug

Just when we wanted to stabilize KDE-4.6, an unpleasant surprise appeared out of nowhere. For no apparent reason, polkit was failing to make DBUS connections. As one consequence, some users could not log into KDE; the desktop would simply hang during the session initialization. After upgrading and downgrading packages, and after a lot of communication on bugzilla (since noone from the Gentoo KDE team could reproduce the bug), a pattern emerged: net-libs/glib-networking- was somehow causing the problem, force-unmerging it with "emerge -C" restored correct behaviour. Later, this was narrowed down to net-libs/glib-networking[libproxy].

Minus docs and debug info, this is what is installed by glib-networking:
Which leads to the question, how can these seemingly unrelated libraries
cause DBUS hangs. Let's just say, the Gnome guys did not know either, but obviously the most intrusive part is the proxy autoconfiguration service registered in dbus.

As KDE-4.6.2 stabilization was pending, one way to temporarily get around the problem was to block concurrent installation of net-libs/glib-networking[libproxy]. After all that package appeared only on 24 Apr 2011 (one week before the bug report was filed) as ~arch in the main tree, and is hard-required in exactly one package (net-voip/telepathy-gabble). Yes, we checked that thoroughly before. User responses however were not so, err, welcoming.
"Anyway it is high time ppl start thinking before committing any changes in the main tree... even if we are talking about an unstable ~ stuff..." (bug 365479, comment 38)

"Now we have repeat with strange blocker... and all because some guy forgotten (or didnt want to) try it before pushing into tree... Sometimes i think that Gentoo developers comes from the round-up." (bug 365479, comment 43)
Ah well. Now the blocker is gone again and we won't hinder people from shooting themselves in the foot, but we still dont know what actually the problem is. In any case, libproxy seems to be prone to more misbehaviour (what the %$&%$ is it doing in NVidia OpenGL code??!!). So far the reports of various details do not really add up to a coherent picture.

Saturday, April 30, 2011

Finished something, finally

The last weeks were actually a busy time for several reasons. Well, there's one less now: at work, yesterday Friday evening at around 21:00 I finally submitted a manuscript (5Mbyte pdf) for publication that we have been preparing for ages.
The whole story started with measurements done in our lab last year, where we look among other things at electrical currents through single carbon nanotubes at very low temperatures of a few millidegrees above absolute zero. In this particular case, the metallic contacts to the nanotube were made of a magnetic PdNi alloy, which means that you have to take into account the magnetic moment (the spin) of the electrons in the contacts and of the electrons passing through the nanotube. Models for such systems have been developed and measurements done for some time already, but together with our theory colleagues from Chonnam, Poznan, and München we have shown for the first time that even quantitatively these models can be reduced to the non-magnetic case with a rather straightforward transformation, and that still the calculations fit the data very well. That is a pretty nice result, since for the emerging technology field of spintronics control of all these current transport effects is quite important.
Now it's time for new projects (and for awaiting the referee reports)...

Wednesday, April 27, 2011

Things I always wanted to do... :)

Andreas K. Hüttel changed:

           What    |Removed              |Added
                 CC|                     |,
                   |                     |,
                   |                     |,
                   |                     |,
                   |                     |,
                   |                     |,
                   |                     |,
                   |                     |,
                   |                     |

--- Comment #4 from Andreas K. Hüttel 2011-04-27 21:31:53 UTC ---
Here comes the big one. On behalf of the Qt and KDE teams:
Arches, please test and stabilize the ebuilds listed in the
attached text file. The list includes core KDE and Qt packages,
their depedencies and extragear/misc KDE/Qt apps as well


Friday, April 22, 2011

KDE 4.6.2 news & upgrade guide

Just to give everyone a quick heads up, the stable request for KDE SC 4.6.2 plus KDEPIM is likely going to be filed soon. On the whole, the upgrade should go very smooth. In case there are problems, we now have a Gentoo KDE 4.4 - 4.6 Upgrade Guide, covering the most frequent issues. In addition, it probably never hurts to look at the general Gentoo KDE Guide.
If you want to test before the actual stabilization takes place, just grab the keyword file... Cheers!

Wednesday, April 6, 2011

KDE 4.6.2 - looking for testers!

You may already have heard that a new version of the desktop environment came out today. (No, not the other one.) I'm talking about KDE 4.6.2. It is in my opinion shaping up rather well, and we in the Gentoo KDE team consider it a candidate for stabilization in a while. (It's about time, since upstream considers our "stable" KDE 4.4 rather "dead".) You can look up the list of important known issues on our bugzilla; some of this definitely has to be fixed before stabilization, but on the whole the list looks manageable.
So, we need testers. Especially since we all from the KDE team have been running newer KDE versions for ages by now and have never tried the direct step from 4.4 to 4.6. If you are brave - sync your portage tree, grab the keyword file, place it in /etc/portage/package.keywords - and update your system! As additional bonus, you will get also updates for QT, koffice, digikam, and some more packages...
If there are dependencies missing in the keyword file, please file a bug! If you encounter any build problems, please file a bug! If you see any misbehaviour after the upgrade, please file a bug! Thanks a lot in advance!
Oh yes, one last note. The kdepim guys obviously don't feel like releasing at all, so everything from kmail to blogilo will remain at trusty version 4.4. This is, however, nothing to worry about. (I'd worry a lot more about the kdepim update should it ever happen...)

Saturday, March 19, 2011

Impressive sci meeting

As you can see from the above picture, it's travelling time again for me. The weather is great, the snow as well, there are a lot more photos to prove it... :) However, not all is skiing and vacation. The real reason for the stay here in La Thuile at the top end of the Aosta Valley is a scientific conference, "Rencontres de Moriond 2011: Quantum Mesoscopic Physics". This is indeed one of the scientifically best meetings of this field, with worldwide attendance. (The excellent skiing opportunities and the great Italian food may of course help attracting people.) Talks go from 9:00 to 12:30 and from 17:00 to 20:00. (I'm writing this at ~22:00 of the last evening and don't count the coffee cups anymore.)

I met here a friend again, one of the powerusers who initially introduced me to Gentoo. As we're at a conference we got talking about doing presentations with Linux, and he showed me a really neat Python program for that. (Normally I don't touch anything Python except with a very long stick, as it would interfere with my daily prayer to Larry Wall. Just kidding, well about the prayer at least...) I found out that a previous version of it had already been available in Gentoo before as "keyjnote". Keyjnote development is not continuing, but a new project named Impressive picked it up. With its new upstream name the program also got a new ebuild name: app-office/impressive. Apart from being a pretty stylish pdf viewer, and integrating/cooperating nicely with dev-tex/latex-beamer and (open|libre)office impress, one of the great advantages of Impressive is that arbitrary python hooks can be added to each slide. Want to play a sound, a video, ...? Want to have a robot voice read out your presentation? Sure, can do! Give it a try!

Sunday, February 13, 2011

Gentoo's Reform and Future @ FOSDEM

For all those interested who could not make it to Brussels, the talk by Petteri, Roy, and Jorge on "Gentoo's Reform and Future" is now online at YouTube - or below. Cheers!

Tuesday, February 8, 2011

Most obscure e-mail of the year (so far)

I have the vague feeling that somehow this is out of my field of responsibilities.

From: xxx xxx <>
Date: Today 05:24:03
Spam Status: Spamassassin 0% probability of being spam.

Andreas K. Lord Huettel

gcam-2010.07.27.ebuild USD?




Sunday, February 6, 2011

Fries, FOSDEM, Delirium Tremens

And here I am now reporting from an extended weekend in Brussels. It's kind of stupid that I have to leave Regensburg just at the moment when results in the lab get really interesting. But then, I'm staying online all the time anyway, and this weekend is FOSDEM time. Definitely a great opportunity to meet with some of the other Gentoo devs face to face. We had the Gentoo developers FOSDEM dinner yesterday, finishing with good Belgian beer near the Grand Place. So far it has been a lot of fun. We even have quorums for both the Gentoo Council and the Gentoo KDE team here...

At the conference site I sometimes have this weird feeling of visiting the nerd pole. One of the events definitly freaking out the locals was the outdoor GPG keysigning. Imagine cold windy weather and 150 geeks standing in a line along the curb and swapping passports for two hours... Just now I'm listening to an interesting and very funny talk about the LibreOffice fork. ("Are you German? We need your help deciphering the code comments! What does 'Manta-Hack' mean? And, 'Wenn Sie das lesen können, haben Sie eine Waschmaschine gewonnen!'???)

The weekend is way too short anyway. Somehow I was not that much excited about visiting Brussels for the third time. Frites and mussels, bah. Now that I'm here, though, I think I should definitely come again. I barely remember the place, there are so many things to (re)visit, art nouveau buildings to discover, flea markets to stroll across, and everything related to Gaufres and Chocolat just has to be good. Cheers!

Thursday, February 3, 2011

Gentoo and GPIB (IEEE 488.2) device control: sci-libs/linux-gpib

Most of you will probably never have heard of the GPIB (IEEE 488.2) bus before. It's a pretty ancient (1960!), but robust parallel bus for addressing lab measurement equipment, which now supports up to 8 Mbyte/s. A clear specialist application, but one that is common for example in university labs all across the world. A typical PCI adapter card costs somewhere around €1k, a typical 3m cable (heavily shielded) somewhere around €250, but then, in many cases the attached hardware is far more expensive.

Under Linux, there are basically two ways to adress GPIB hardware:

As much of the hardware is bought from National Instruments, one is the proprietary National Instruments VISA driver stack on top of NI's GPIB hardware driver. This works very reliable (once it's installed), supports e.g. LabView for Linux (eurgh), and NI is actively developing drivers for (some of its) hardware. So much for the good sides. Here are it's disadvantages:
  1. installation is basically doing its own package management, only very few (mostly outdated) linux distributions are really supported and trying others can be a serious pain, and the entire installation process is fundamentally incompatible with portage (I've been trying to beat it into an ebuild for a while and this is a sure way to madness); 
  2. since the Linux kernel USB interface is declared GPL-only, no GPIB-USB devices are supported since kernel 2.6.24.
For those trying to use the excellent NI GPIB-USB interfaces in their labs, even NI employees point to the second option: the open-source (GPL) linux-gpib package. While its development has stalled in terms of features, it supports the usual hardware fine and interfaces even with most recent kernels, and the author wants to maintain it further to that effect. For this package, we now have an ebuild in Gentoo: sci-libs/linux-gpib. It is still package-masked since the installation needs testing. While we do have the required hardware in our labs, I have not had a chance to set up an entire Gentoo system there for it. But- if you have been working with linux-gpib and maybe even with one of the inofficial ebuilds before, please give it a try and report your experiences on bug 165399.

As a final remark, probably the best possible support would be to combine the open-source linux-gpib hardware driver with the NI VISA intermediate layer. Unfortunately, this would mean linking a GPL library and proprietary code, so no-go. At least as long as nobody budges...

Friday, January 28, 2011

New digikam and kipi-plugins 1.8.0

Another month, another bugfix release from the digiKam team, and it's already in the tree. Enjoy, and remember, this all needs at least KDE 4.5!

As a side note, please don't expect any working ebuilds for digikam-2.0.0_beta1. First, the great new upstream feature is bundling of all the required libraries, including even some pre-release of kdegraphics-4.7(!). Several maintainers have already pointed out that this is not such a great idea, with no effect so far... Second, the entire source tree layout may still change until 2.0.0 release, so this is a bit like chasing a butterfly...

Thursday, January 20, 2011

P=NP, the next try

It could be hot, if it were correct. Now, it has to survive the scrutiny of mathematicians and theoretical computer sciencists from all over the world: Vladimir Romanov has published in his blog and on the arXiv a manuscript with an (as he says) polynomial-time (i.e. "fast") algorithm for the so-called 3-SAT problem from theoretical computer science. Now, that particular problem is known to be one of the class of NP-complete problems, and if any NP-complete problem can be solved in poly-time, then all NP problems (these are "hard ones") can be, i.e. P=NP with P as the set of problems solvable in poly-time. This may sound pretty exotic, but it has enough interesting consequences to make P?=NP one of the fundamental Millenium Prize Problems of the Clay Institute. Interesting times and a potential $1.000.000 bounty ahead...

Yay! Another KOffice version bump!

In a way this blog post is a bit late, since the "big bump" from KOffice-2.2.2 to KOffice-2.3.0 was already a few days ago. But- starting now, we have the brand new zero-day version KOffice-2.3.1 in Gentoo portage, ready for your perusal. Keyword and enjoy!!!

As a side note for those who have not heard it yet, the KOffice 2.3 series will be the last one with that well-known brand name. Owing to certain disagreements and an effective fork of KWord, development will continue as "Calligra Suite", with some less-than-inspired new application names (Words, Tables anyone?). Ah well.