XCSoar and LK8000

LK8000 was forked from XCSoar 5.2.3 in 2009 by Paolo Ventafridda. It was illegaly distributed for more than a year, because Paolo Ventafridda refused to open the source code. He has continuously flamed and insulted me personally, despite my best efforts to rejoin the two projects under one large hood.

This page is not supposed to help you choose one or another program, because all of that may not matter to you. This page is only supposed to tell what really happened with quotations and links to the original posts.

Original opinions expressed on this page are my own, they are not an official statement of the XCSoar developers.

Table of contents

• The Birth of LK8000
• LK8000 is illegal
• LK8000 code cleanup
• Live OLC scores
• LK8000 on Android
• Funny quotes

The Birth of LK8000

My first post to the XCSoar developers was in June 2009:

“I have a brand new HTC Magic mobile phone with Android. […] My idea was to use the phone for two things: […] 2. run xcsoar during flight. Has anybody tried to port xcsoar yet?” Max Kellermann

Soon, I found myself in the position to do the port myself, which turned out to be extremely difficult with the given code base:

“I believe that the XCSoar code base is in a very bad shape. There are so many global variables, there are too many cross references (everybody imports everybody’s symbols), bad modularity. I’m not trying to put blame on anybody, that just how large projects grow over the years. I’d like to constructive by helping tame the code base.” Max Kellermann

I posted many patches to clean it up, to separate out reusable libraries. Paolo wasn’t comfortable with that:

“I spent months to understand how this code is working, and started to add functionalities. If you now change everything, doing a revolution on the source organization, I shall have to spend more time on it. […] This is not the way things should work. You can’t change the pavement while I am walking on it. […] I care about XCSoar and I will be spending my time on it, and not on your porting problems.” Paolo Ventafridda

“Sure. And what about those poor old developers that all of a sudden discover that you have moved part of the codes here and there? “Paolo Ventafridda

“Not a good idea all these patches right now. While I understand that these patches have a meaning for porting the thing to another platform, I simply can state the fact that if I don’t apply these patches against my version, which is not updated to Max’s, then I’ll loose any chance of alignment in the next future and necessarily shall fork out.” Paolo Ventafridda

Paolo’s problem was that he had been developing patches which he did not publish, which he did not submit for merging. As long as XCSoar development was slow, this works well. But once the “original” code changes a lot, his patches don’t match anymore, and he has to rewrite them.

I posted suggestions on how to resolve that, but Paolo acted like a child:

“if Max patches are in, it means I should spend the next weeks trying to patch the code, understanding this new library approach, and testing the result. I fork out. “ Paolo Ventafridda

“And there will stay, out of my hard disk.” Paolo Ventafridda [talking about the patches I submitted]

Shortly after that, Paolo renamed his private XCSoar version to “LK8000” (“Look like LX8000”).

LK8000 is illegal

In 2009, Paolo Ventafridda has willfully violated the XCSoar copyright by refusing to publish the LK8000 source code. He has kept it secret for a year, before he finally opened his sources in 2010. That is what we know so far.

What may be surprising to some: LK8000 is still illegal!

The GPLv2 says: “Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License.”

This means Paolo’s rights under the GPLv2 have been terminated in 2009. He is no longer allowed to modify or redistribute XCSoar, no single piece of it, not even LK8000 (which is a derived work of XCSoar version 5).

How would Paolo be able to recover from this unpleasant situation? Paolo would have to apologise to the XCSoar 5 copyright holders, and every single copyright holder would have to forgive him.

What if Paolo ignores this problem? Any single copyright holder can sue him for copyright violation at any time in the future. A court may decide that Paolo has to pay license fees retroactively, and forbid him (and anybody else) to continue the LK8000 project, because it is based on an illegal copy of XCSoar 5. This problem doesn’t go away by ignoring it.

Follow-up

“He forgets to note that XCSoar has been illegal for 4 years not distributing the DLL for OLC validation” Paolo Ventafridda

Nice try, Paolo, but wrong. That has never been a problem for XCSoar, for two reasons:

• The GRecord.dll source code was never a secret, it was just that nobody sent a formal request for its source code. When I did, my request was fulfilled, in accordance with the GPL.
• But, assuming GRecord.dll was really non-free (which it is not): who could sue whom? Any XCSoar copyright holder who did not explicitly forgive you can sue you for LK8000 at any time in the future. But who can sue whom for XCSoar’s GRecord.dll? You? No, you came late to the game, and by contributing despite of knowing, you implicitly agreed to the status quo.

Despite of claiming that XCSoar is illegal because of GRecord.dll, Paolo Ventafridda continues distributing it with LK8000. One needs a strong reality distortion field to hide that contradiction.

LK8000 code cleanup

In 2009, Paolo left the XCSoar project because of my efforts to clean up and reorganize the code:

“I spent months to understand how this code is working, and started to add functionalities. If you now change everything, doing a revolution on the source organization, I shall have to spend more time on it. […] This is not the way things should work. You can’t change the pavement while I am walking on it.” Paolo Ventafridda

Then, two years later:

“I have started a general cleanup of code. […] (phase 1) clean up the code (phase 2) reorganize the code” Paolo Ventafridda

In other words: “I was so wrong in 2009, and you were right from the start.”

Live OLC scores

When XCSoar implemented live OLC scores in 2009, Paolo Ventafridda said that wasn’t important, people were not asking for that.

In 2011, Mateusz Pusz implemented the same for LK8000, borrowing ideas from XCSoar. Although it is so unimportant, it is going to be one of the key features of LK8000 2.2 (link1, link2, link3).

“Mat did a wonderful and very difficult work, alone.” (Paolo Ventafridda)

“No other software on the market, or free, to my knowledge has these features” (Paolo Ventafridda)

Mateusz Pusz then pulled a few numbers out of nowhere:

“Fast - my test application is 130x faster than yours for the same trace” (Mateusz Pusz)

A few weeks later, he exaggerated even more, although we had already explained that his numbers are invalid (but our posts on the forum were censored):

“Execution time on my PC: XCSoar 976s, LK8000 0.8s” (Mateusz Pusz)

We cannot post rebuttals on the LK8000 forum, because Paolo Ventafridda has banned our user accounts there, and he keeps on deleting all of our posts. So here is why Mateusz Pusz is completely wrong:

• Mateusz used our program “TestOLC”. That is a program to test (debug) the OLC code, not to benchmark it. On the other hand, LK8000’s program “TestContest” is specifically designed for benchmarking.
• By default, compiler optimizations are turned off in XCSoar, and debugging code (like assertions) are enabled (not so in LK8000). This is a slowdown by the factor 6. I suppose Mateusz does not know that, and he compiled without explicitly turning on compiler optimizations.
• TestOLC uses the Replay library, which uses an interpolator to calculate missing points, at least one per second. That multiplies the load by about 10.
• TestOLC uses the Trace library, which uses a KDTree. The same Trace object is used internally to draw the trail and to calculate live contest scores. For drawing, the KDTree is important, but for score calculation, it is useless. That overhead is very visible in TestOLC, but in the “real” XCSoar where it really counts, there is 0% overhead, because the KDTree is needed anyway (at the bottom line, it actually reduces overhead).
• XCSoar’s OLC code uses a Trace with 1000 points, while Mateusz (knowing that) chose to use only 100 points. That decreases the accuracy of the result, but makes it look great in a benchmark. Factor 10.

Mateusz should know better than this.

So here’s XCSoar’s real performance: I have benchmarked both with the same trace size, calculating this flight on a Core i7-920 running Linux. The Linux “perf” utility was used to measure the CPU usage of both.

The result: LK8000 took 373 ms, while XCSoar finished after 56 ms.

Detailed numbers:

For another benchmark, I have configured LK8000 to use the same trace size as XCSoar. Let the numbers speak for themselves:

Yay!

The following commands were used to compile LK8000’s TestContest and XCSoar’s TestOLC:

make -C Common/Utils/TestContest/ TARGET=UNIX
make TARGET=UNIX DEBUG=n output/UNIX/bin/TestOLC

LK8000 on Android

I joined the XCSoar project in 2009 specifically to port it to Android. That was a huge amount of work, it has taken nearly two years, but now it’s done.

“At present I don’t plan to move to linux or android.” (Paolo Ventafridda)

Later in 2010, Paolo had an idea: he doesn’t need to make LK8000 portable, he just needs VMWare:

“In the meantime, it looks like a VMWARE machine will be running CE under linux, so theorically LK8000 could run perfectly on Linux soon with no efforts for me.” (Paolo Ventafridda)

“I am keen on thinking that VMware is going to run on Android as it is doing on linux already. So LK8000 can already run on a virtual machine running XP.” (Paolo Ventafridda)

Yes, Paolo is serious: he wants to run LK8000-PC on Windows XP (for x86 CPUs) on VMWare on Android on an ARM CPU. What he does not know (and refuses to understand even after explaining it to him) is that VMWare is not a CPU emulator, it is just a virtualization software which runs the guest software on the “real” CPU. And: embedded VMWare is supposed to be a hypervisor; it is not going to be a software you can just install inside an existing OS.

In the meantime, XCSoar for Android has been finished, and runs extremely well. That makes Paolo jealous:

“2 years of development for an android version which looks like a DOS program, full of bugs, and nobody using” (Paolo Ventafridda, he has deleted that post meanwhile, mirror here)

At the time he wrote that, more than 1,500 people had already installed XCSoar on their Android phone/tablet, getting more every day.

Then, unexpectedly:

“Porting will start after version 3.0 is out, in 2012. We are migrating to version 3.0 removing all microsoft dependancy” (Paolo Ventafridda)

In May 2011, somebody posted to the LK8000 forum:

“I am sure the development team will hate me for this but…. My I add to the pleas for an Android version? In my case, I see an Android version of LK8000 as a significant safety benefit for those users with Andriod phones.” (JBlyth)

Amusingly, that post got censored after a few hours, but here’s a mirror.

In June 2011, Paolo seems to have realized that censoring his user’s feature requests is an insult, and that there is a huge demand for gliding software on Android. Response to yet another request for LK8000 on Android:

“We shall take a decision on when to start porting to android in september.” (Paolo Ventafridda)

I claim: LK8000 on Android is vaporware. None of the current LK8000 developers are up to the task of porting it to Android.

Paolo is still spreading bullshit about InfoBoxes, saying they are not portable and must be removed for the Android port. But, XCSoar’s InfoBoxes work just fine on Android, you say? See, that’s why I have little confidence that LK8000 will ever be ported to Android.

No LK8000 for Windows CE

In December 2011, there was an announcement that work on the Android port will finally start in January 2012:

“There are no more obstacles to port the 3.0 to Android. […] The scheduled activities were to clean up the code while still programming the 3.0, in order to be able to start porting by the end of january 2012” (Paolo Ventafridda)

2011 went, 2012 came, and in January, a new announcement looked very different:

“If personally, alone, should be doing the porting to android, I wouldnt keep any compatibility with CE. […] Just like there is no compatibility for user interface between DOS and Windows. I would keep the LK peculiar user interface and trash configuration, buttons, etc. belonging to 2004” (Paolo Ventafridda)

This sounds exciting: there will be LK8000 for Android, but it will be a rewrite. The “old” LK8000 and its user interface will be deprecated and discontinued. Which means: if you buy a Windows CE device now, it will be useless once LK8000 for Android goes public. If you buy an Android device now, XCSoar is your only choice, because I still believe that LK8000 for Android is vaporware.

Funny quotes

• 2009 Paolo Ventafridda: “if Max patches are in, it means I should spend the next weeks trying to patch the code, understanding this new library approach, and testing the result. I fork out.” (This was the birth of LK8000)
• 2009-09-14 Paolo Ventafridda: “No. You are an arrogant person, I will not deliver to you a single line of code.” (Denying my request for the LK8000 source code)
• 2009-09-15 Paolo Ventafridda: “in the end you are only changing the order of lines and files, and renaming functions ! You are adding 1000 bugs, hehe.”
• 2009-09-15 Chris Rowland: “Or are you just a load of arrogant, intolerant, open source zealots who would rather destroy what we have than tolerate anything that disturbs your mindless obsession with source purity. You disgust me.”
• 2009-11-13 Karim Trojette (a.k.a. “KT1”, “modellbobby”, “TRKA”): “Das einzige was Du gemacht hast bei XCSoar ist der halbgherzige Portierungsversuch nach Linux. Nichts weiter hast Du gemacht ausser dumm rummotzen. […] Lass es lieber sein. Wer selber nix geleistet hat, sollte sich auch nicht immer so aufplustern.”
• 2009-11-23 Karim Trojette: “ACHTUNG: Ich bin einer der BetaTester von LK8000 und muss euch vor der XCSoar Version 5.2.4 warnen. Wir testen und bauen immer schwerwiegendere Fehler aus dem alten Code aus. Bsp: Waypoint reachable calculation, terrain collision, schwere Programmabstürze wegen falscher Berechnungen etc etc. Jeden Tag kommen neue Fehler ans Tageslicht. Also bitte aufpassen!”
• 2009-11-24 Karim Trojette: “Ihr habt sie echt nimma alle.”
• 2010-01-18 Thomas Weinberger: “We’d probably be better off without guys like you.”
• 2010-09-02 Sérgio Da Silva: “You make me laugh!!!!!”
• 2010-09-02 Karim Trojette: “Max, no one cares about your opinion here and we all laugh about the illegal 5.2.4. YOU acted like a offended child and for this reason dont be surprised about the fact that nobody wants to work with you. I believe you are every hour scanning this forum and trying to either copy functionalities or trying to sabotage this project.”
• 2010-09-03 Thomas Gemmel: “Max Kellermann, GO AWAY!!! You have nothing to do with the development of LK8000 (Thank God!) So stay out of this Forum!” (after Paolo addressed me with a question in the same thread)
• 2010-09-06 Thomas Weinberger (aka Uncle Tom) <it-sec@gmx.net>: “Gott bist Du ein armselig arroganter Besserwisser. Ein wirklich beispielhaftes Exemplar dafür, dass kognitive Intelligenz nicht notwendig mit sozialer Kompetenz einhergehen muss. Hast Du eigentlich ‘ne Freundin?”
• 2010-10-06 Karim Trojette: “Disqualifizierung +1 Max! Schon mal was von Bind oder dynamischen SQL gehört? Optimizer? Zugriffspfad? DB2? Scheint nicht Dein Fachgebiet zu sein! Wie war das mit dem gefährlichen Halbwissen”
• 2010-10-06 Karim Trojette: “Wollen wir mal zusammen Deinen Schrottcode durchschauen?”
• 2010-10-19 Karim Trojette in an Email to Triadis (a commercial XCSoar vendor): “im LK8000 Projekt haben wir unzählige schwerwiegende Bugs aus dem XCSoar Code gefixt. Ich möchte Ihnen mitteilen, dass Sie, wenn Sie nicht selbst diese versteckten bugs gefunden haben, ein riesiges Problem haben. Wingloading, Final Glide, Terrain Kollision etc. alles ist falsch”
• 2011-03-10 Paolo Ventafridda: “I am sistematically removing any message from Max here”
• 2011-03-10 Paolo Ventafridda: “We start rewriting the stuff using new user interface, so that instead of doing like Max Kellermann did (2 years of development for an android version which looks like a DOS program, full of bugs, and nobody using) we shall be porting a widely used and accepted software to a platform using the OS innovative functions.” (He has deleted this post meanwhile - mirror here)
• 2011-03-10 Paolo Ventafridda: “Max Kellermann is currently leading, or he thinks he is leading, the 6.0 development of xcsoar. It seems that he has some problems with us, because he keeps on writing here and there (postfrontal, and foreign forums) against what we do. He also contacted developers of lk one month ago, practically asking them to abandon the current project. I asked him, and his fellows, to stop. We don’t write on their forum. I am now inviting people in germany to ask him politely to dedicate his time to whatever he likes, forgetting what we do and LK. If you think you can help us solve this problem, locally in germany, please contact me privately for further details.” (after Paolo censored a bunch of harmless comments from the LK8000 forum, e.g. one asking for the difference between the new “Bottom Panel” and the old “IBOX mode” - mirror here)
• 2011-03-16 Paolo Ventafridda: “In the past Max has been claiming copyrights on LK, finally admitting that no, it was not true.”
• what really happened, here’s my post: “It turns out that LK8000 is not based on XCSoar 5.2.4 (like Paolo said several times), but was forked at some point shortly after 5.2.3. […] Which means I am indeed not a copyright holder of LK8000. My copyright claims were based on Paolo’s statement that he forked off 5.2.4, which is not true.” and Paolo replied in the same thread: “I admit I made a bit of confusion with those versions.”
• 2011-03-17 Sérgio Da Silva (tiguy82): “You just make me laugh!!!!!”
• 2011-03-17 Sérgio Da Silva (tiguy82): “Tell me why you always creating problems!!????!”
• 2011-03-17 Sérgio Da Silva (tiguy82): “I think Max didn’t make his homework!! Search before Talk!”
• 2011-03-17 Paolo Ventafridda: “Where is the copyright gpl problem with xcs and this code published by Stein, exactly? We all deserve an answer now.” - don’t ask me on a forum where you banned me a week earlier ;-)
• 2011-03-18 Sérgio Da Silva (tiguy82): “Max is going to sue Microsoft, Google and even Apple really soon!”
• 2011-03-27 Paolo Ventafridda: “we are releasing 2.1e with working new OLC engine. […] No other software on the market, or free, to my knowledge has these features.” - XCSoar has had it for a while now, Paolo knows that, and when John replied, Paolo deleted John’s post and banned him
• 2011-03-31 Chris Rowland: “I wouldn’t develop it with Kellerman’s attitude that any use of code that he disapproves of is theft and his aggressive use of his interpretation of the GPL to try to enforce this. His whole attitude that this is “offending code” makes this far too risky.”
• 2011-04-01 Chris Rowland: “I will not be a party to the evil that I think that you are doing.”
• 2011-06-07 Sérgio Da Silva (tiguy82): “When Paolo decide to give support to paragliding mode I didn’t see ANY post from you talking about it!” - because that was one month before I joined the XCSoar project.
• 2011-07-05 Paolo Ventafridda: “under no circumstance I will ever accept a single bit of code from a person that holds a blog against me” - rejecting a bug fix that I submitted.
• 2011-07-05 Paolo Ventafridda: “Turbo, I have enough. Do not come here anymore bothering me and this forum. Understood? Banned.”
• after Tobias asked about an algorithm that allegedly made LK8000 scale extremely well - the truth is, LK8000 iterates over all waypoints, which scales poorly.
• 2011-07-05 Paolo Ventafridda: “I have removed all messages, I am sure the Idiot will have a copy of them. He has nothing else to do all day.”
• 2011-07-29 Paolo Ventafridda: “he is distributing at his name on android market the xcsoar software which is using some of our translations (copyright by respective authors) some of my code and probably other’s also, without printing the copyright authors anywhere.” - yeah, right.
• 2011-08-01 Paolo Ventafridda: “I could sue Max Kellermann for a bunch of real reasons that have nothing to do with copyrights but with diffamation” - does “You are an arrogant person” count as “diffamation”?
• 2011-08-01 Paolo Ventafridda: “If LK is illegal, then XCSoar is even more illegal right now” - this chain of evidence is somewhat incoherent.
• 2012-07-05 Paolo Ventafridda: “Xcsoar copis code and ideas from LK, not the contrary. We rule.”
• 2012-07-11 Paolo Ventafridda: “We are not under democracy here: this is a forum about LK8000 and I manage it.”
• 2012-07-23 Paolo Ventafridda: “I believe now you are mentally instable.”
• 2012-07-23 Paolo Ventafridda: “In no case you will allowed to enter as a virus (or better say as a cancer) our project.”
• 2012-07-24 Paolo Ventafridda: “You have serious mental problems! Get a doctor!”
• 2012-07-24 Paolo Ventafridda: “Stop stalking me, Kellermann!”
• 2012-07-26 Paolo Ventafridda: “let’s stay away from you, Kellermann, by all means!”
• 2012-07-26 Paolo Ventafridda: “Stop stalking, or I call up your parents asking them to stop you. Understand?”
• 2012-07-27 Paolo Ventafridda: “When I mentioned your parents, Kellermann, I was not joking. When I publish your personal page be assured they will be pointed to it, and their customers too. I am going to help you understand how is life when you publish a blog against a person. You lucky man!” This is my reply.
• 2012-12-11 Paolo Ventafridda: “The reason LK was created is that I was going to spend more time discussing things with you, than doing them by myself and my own.” (what really happened)