It feels like I'm sitting in a roller-coaster wagon. There's probably too much change going on for me to assimilate naturally. In particular: I just wrapped up (well, mostly) one of the toughest Uni semestres. I had to deal with lots of very time consuming assignments, and then the usual round of final exams. Even if this semester I got the best marks in my journey (or shall we say Via Crucis) through University, I still managed to fail one exam, for the Advanced Networks subject, which is quite annoying, given I got high marks (even the highest in one case) in other subjects I really don't master at all. In any case, this is the end of the pain. The only thing that's left is just one exam and a project based on GNU/Linux technologies which will basically mean formatting for prettyness the sysadmin docs we've been collecting at the office during the last few years. This effort will be nothing to what I've been doing during the past 18 months, so I'm really relieved to have it past me already. Getting rid of studies comes just two weeks before a big change in my professional career. Friday was my last day at the Institut Tecnol gic d'Inform tica, after five and a half fantastic years working with awesome people in a very friendly atmosphere. I've learned a great deal, and taking this decision wasn't easy at all. I leave lots of good friends behind, people I really love, and tomorrow will be difficult to not have them around me. I wish my ITI ex-workmates the best of luck in these difficult times for everyone in Spain and specially in the Valencian Country with the massive cuts going on. I feel the timing for this jump couldn't be better. Tomorrow, when I get ready to go for work, I won't be leaving home at all, instead I will just sit where I am right now, at home, and log into some corporate IRC server. Tomorrow I'll be joining Collabora, and I'm a mix of excited, curious and happy about this incredible opportunity. Thanks to Sjoerd for nags, I might not be writing this if it wasn't for you!

When I was first approached about this, I thought Collabora was a small company. But as I looked more into it, I discovered that's not longer the case, there's many more people than I imagined working there (here!), and was delighted to see I knew many of them, and many other are well known members of the major Free Sofware communities. I'll be joining the sysadmin team to work closely with Jo Shields. See you tomorrow, folks. :) This opportunity to work from home is godsend, given the third bit of change that'll be happening soon: sometime in late September, Maria and I should join the ranks of first-time parents, following the baby boom wave surrounding us. While you can imagine we're really happy about this, we're also freaking out because this is going to happen in just two months and a half, and weeks go by really fast lately. So yeah, being able to be at home with this really small baby will be a big bonus for the incredible experience we're about to enjoy. We've been both busy with other stuff, but during the summer we should be focusing on preparing the baby's arrival. There's a whole lot to do! Expect my Debian and other Free Software activities to get a hit, of course. :) If I am normally sleep-deprived, this is going to be the next level.

Assume the following situation: You set problem sheets for a class, and at the end of the semester, you have 13 individual LaTeX files, including the preamble (the stuff from \documentclass to \begin document ). Now you want to provide a file that contains all problems, followed by all problems with solutions. You could just concatenate the resulting PDFs, but that would waste quite a bit of paper, as most problem sheets do not fill the whole page. You could just copy n paste the LaTeX code, but that is not neat either. So you want to include the 13 individual documents in one LaTeX document. LaTeX provides \include and \input commands, but these would require that the content of the individual files, i.e. the stuff between \begin document and \end document , is put in a file of its own. You cannot just \input the full problem sheet document, as there must be only one \documentclass command, and a few preamble commands are invalid within the document. There are various solutions suggested, e.g. on Wikibooks and StackOverflow, and there are packages helping with that functionality, such as combine or subfiles. I chose a rather rough, hands-on solution that worked great in my case: The idea is to simply re-define all commands that you have in your preamble to do nothing, including the document environment, before including the other files and constraint to a group. In my case, the preambles were relatively small, as the common definitions of the problem sheets were in a file of their own. I am also using the \foreach command provided by the TikZ package for a convenient loop over all problem sheets:

\foreach \x in  0,...,13   
   
    \excludecomment solution 
    
    \DeclareDocumentCommand \documentclass om 
    \DeclareDocumentCommand \usepackage om 
    \newcommand \Blattnummer [1] 
    \DeclareDocumentCommand \FirstDueDate mmm 
    \DeclareDocumentCommand \ThisDueDate mmm 
    \newcommand \SkippedWeeks [1] 
    \renewenvironment document 
    \section* Problem Sheet \x 
    \setcounter problem 0 
    \input GraphTheoryProblems\x 
   
 
\clearpage
\label sols 
\foreach \x in  0,...,13   
   
    \newenvironment solution 
      \par\addvspace 1em 
     
     
    \DeclareDocumentCommand \documentclass om 
    \DeclareDocumentCommand \usepackage om 
    \newcommand \Blattnummer [1] 
    \DeclareDocumentCommand \FirstDueDate mmm 
    \DeclareDocumentCommand \ThisDueDate mmm 
    \newcommand \SkippedWeeks [1] 
    \renewenvironment document 
    \section* Solution Sheet \x 
    \setcounter problem 0 
    \input GraphTheoryProblems\x 
   
 

To redefine commands taking optional arguments, using the xparse package is convenient. You can see how I include every file twice, first with the solution environment turned into a comment and then again with the solution environment actually showing its content. I create a section header based on the counter of the foreach loop, but I could have easily redefined \title and use that for a header, if my problem sheets had used that command (They don t, as they calculate the problem sheet number and the due date based on the number in the filename very convenient, and maybe worth a blog post of its own). The problem counter is reset for each file, so that the problems are numbered individually. I could have left this out, then the problems would be numbered consecutively across all included problem sheets. The individual and resulting files can be found on the Graph Theory course website.
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Now that the semester is done and now that I have compiled my crazy paperwork for Canada (wow, it is a lot), I will be heading in six days to the wonderful city of Montreal to settle down, at least for a few years. I am ready to leave but it is not an easy move, as I like NYC and my job. I came to New York City for the first time at the age of 19 after spending a year on a ship and I rather did not like the city for those 5 years, although loved my college years and all the time I spent chasing a Frisbee while running on grassy fields all over the east coast. When I left in 1998, I said, never again. But the future is impossible to predict so of course I came back when I got a job, my only job, at NYU MCC and headed quite happily here (incidentally from Canada). And NYC was much much much better the second time around, most likely as I had a salary, and here is what I <3 and loved about the city. 1. Not having a car (which will still be the case in Montreal)
2. The bike path on the Hudson, especially the gardens and the Irish famine memoriall
3. The farmer s markets (won t miss the prices though)
4. High walkability factor (and though I did not love my hood, I loved being 1.5 blocks from my office)
5. The music jam circles in Washington Square Park (I was always left wondering if they were spontaneously generated or long standing groups // prolly both) and the occasional but mighty impressive hawks in the park.
6. Coney Island especially under certain special conditions when you can rly enjoy the lights radiating out of the amusement park
7. Leaving the city for some nature time
8. 24 hour trains (despite not loving them cuz the noise robbed some life from me every time I took them)
9. Grand Central Station s ceiling
10. The gluten free options (this is going to be the hardest to give up as Montreal sort of sucks in comparison)
11. Being able to take your small dog on the train which is only a recent pleasure
12. My department
13. East Asian Starr library at Columbia University (still my favorite library in the world) and totally loathed NYU s Bobst, ugly on the outside, ugly on the inside
14. NYC sunrises which I have like only seen 3 times (sadly) but they have been stunning every time
15. Walking across the Brooklyn Bridge
16. HOPE
17. The Highline
18. The Strand
19. My favorite thing = Massive Snow Storms in the City (good thing I am moving to Canada, eh?)

Oh, boy. Where do I start I postulate that there exists something called the "UI Singularity". Those who spend too much time considering the optimal way to interact with computing devices eventually pass through this singularity and can no longer effectively communicate with those of us on the other side. At least that's one way to explain what seems to be happening to free-software desktop environments. From the outside, it would appear this happened to KDE with KDE 4, and now, unfortunately, it has happened to GNOME, with GNOME 3. I've had GNOME 3.0 running on my Debian laptop for a few months, which I have used casually. At work, we installed Fedora 15 (GNOME 3.0) on our 69-seat Linux lab over the summer, which I have used on occasion to achieve specific things. I haven't dared upgrade my main work machine yet. So, it could be argued that I haven't spent enough time immersed in the GNOME 3 experience to really judge it fairly. On the face of it, I wish 3 was an iterative development from 2, and didn't throw so many babies out with the bathwater. My casual use of it so far has not endeared it to me at all. In the interests of being fair, rather than deliver my opinion of GNOME 3 as it currently stands, I've decided to try and use it in anger for a while to truly see whether I can "get it". Now that we're past the start of term, I am attempting to use a lab-configured Fedora 15 machine as my main work environment. I'll run with this for a while, and then try a Fedora 16 instance (I need to consider whether we should move to F16 for the second semester anyway) to see what improvements GNOME 3.2 brings.

Hello this is the third report regarding my project. As usual, quick
summary first. From my last report I have progressed much little than I
would like but, as stated previously also, I m finishing semester
and between exams and projects it takes almost all my time. However, I m
free of academic duties next week and I ll double the speed on the project. What was done so far

- Started working on the modifications to the Eucalyptus code, as
expected.
I ve almost complete the code for the Libvirt s XML Domain
definition. I ve abstracted the wrapper in order to support a broader
number of arches. Previously it was tailored for supporting x86/amd64
based machines. The idea is to have a list of supported arches and
generate the XML file according that. For ARM some parameters and
elements are different than for the others. This would allow for
people to support another architectures, given they are well supported
by KVM-Qemu.
Started working on changes to util/data.c to make sure the correct
parameters are being passed to the XML generator and to libvirt kvm
calls.
- Define and start to setup the testing / demo environment. Basically
involves having one machine to run KVM as hypervisor so the Eucalyptus
handler uses it to run ARM kvm-qemu images.
- Over this weekend I ll be publising the code changes on my
website. Steffen suggested to create some docs regarding the progress
too. I ll do that once I feel I m on track again for my current
pending work, that s coding. What I ll be working over the next two weeks

- My primary goal is to catch up on the work pace and finish the neccesary
code for Eucalyptus to support ARM images. This means to finish
modifications to:
node/handlers_kvm.c handling nc creation. Little changes are need
here from what I ve indentified already.
util/data. c,h handling instance creation. This is the part where
most of the work shall be done. I ve started to work here already.
- Test the code I ve complete already and send the patches to the teams
involved. To date I m still working on a local environment, because no
usable patches have been generated already, just little pieces here
and there.
- Since this is a sort of gluing project, that is code here and there
and make it work together. I m in the process of finding a machine to
be able to test parts of it once they are complete. I m still
contacting people to get such machine, in anycase I gues I can manage
to get one myself. I can t use my current machine since it involves
reinstalling and working at the OS level.
- For the project s demo I ll use both machines, one as the front-end
and the kvm one for NCs (nodes). That s the goal. What is required after that

- I d like to release a package that includes my changes, so it can be
installed either from official packages or my own packages, this
involves:
Updating the packaging bits to the pkg-Eucalyptus repo.
Talking to upstream about it.
- Write the reference Steffen suggested. I believe that I can finish the first part in one week, because of the
work I ve done in the past weeks to understand the Eucalyptus code. I m
also will be talking more to the Eucalyptus team and also to the
maintainers about such changes. I guess that s all for now.

Hello, this is the 2nd report regarding my project. I'll offer a brief
summary of how are we doing and then the details, so you don't have to
read everything at all.
I have to start saying that over the last two weeks I made a lot of
progress on the project. The most important part: Debian ARM image
integration with Eucalyptus is now cleared. The work to be done for the
next two weeks is pretty much fully coding to achieve what we've committed:
supporting Debian ARM images for Eucalyptus.
What was done so far
--------------------
- I've have identified and mapped what needs to be modified over the
  eucalyptus source for supporting ARM. I'm puting the details on the
  next section. I think this is the most crucial part that is now
  sucessfully achieved.
- I started a Project Log[1] on the wiki, so anyone can check and
  eventyally use the information I've already gathered. The log is being
  updated constantly. You can also check what I've done and what I'm
  working on.
- We got feeback[2] from Eucalyptus developers and packaging
  team regarding developers and packaging team regarding the ultimate
  source for debian/ packaging bits. This was quite important because
  in the past I've managed to build Eucalyptus from source using the debian/
  included in the upstream tarball. However the people in charge
  told us that they were using a different one, which indeed was
  different and resulted in different output than I expected. I'm
  still working on fixing the bits to get a clean build.
- I've joined the pkg-eucalyptus team and I've been given commit rights
  to the repo[2].
1- http://wiki.debian.org/SummerOfCode2011/BuildWithEucalyptus/ProjectLog
2- http://lists.alioth.debian.org/pipermail/pkg-eucalyptus-maintainers/2011-June/000289.html
What I'll be working over the next two weeks
--------------------------------------------
- Heavily code on the different bits that I've identified and need to be
  changed. They are:
  C code:
  - node/handlers_kvm. c,h  - handles nc creation. nc's are node
  clusters for Eucalyptus, the code is in charge of node creation. It
  prepares the "machine" that is able to run a compatible image.
  - util/data. c,h  - handles instance creation. The code over there
  implements the functions node/handlers_* use, like instance creation
  and libvirt's API parameter passing. Since libvirt's parameters for
  ARM vary from x86's ones, we need to support that.
  Perl code:
  - tools/gen_kvm_libvirt_xml - wrapper tool for creating KVM/QEMU
  libvirt's XML Domain definition. This needs to be heavily
  changed/updated - redesigned, to support ARM architecture.
- Depending on the previous task progress: Modify the Debian packaging
  bits for Eucalyptus and push them to the pkg-eucalyptus's team
  repository. This is not crucial for my project's success but I'd like
  to work with Debian official builds. I've yet to commit the
  Eucalyptus team version to the debian/ dir. I expect to have fixed
  the bits to get a successful and clean build, then commit.
Other plans
-----------
- I expect a slow down on the work pace over the second week due end of
  semester exams on the week from July 3 to July 9. After that week I'm
  on vacations and will be fully dedicated to the project.
- Code changes to Eucalyptus source will be pushed upstream. I would
  not like to keep a separate repo for this. I'll talk about this with
  Steffen. Changes to Debian bits will be pushed to the appropiate repos.
Other bits
----------
When the project started I noted it was too vague for some people and
it's results/output were unclear. This concerned me. However, while the
project started and we got lot of feedback things got much clear and I'd
like to take the opportunity to explain it a bit.
Currently, developers targeting ARM devices are struggling[1] with having
a development environment. There are missing bits that sometimes are not
in place and result on hard time for them. Also, due mobile devices
growth and vendors using Linux-based[2] operating systems it's a nice
opportunity for Debian to keep it's well known fame of: supporting every
arch over the sun. How this project fits, well by offering the ability
for developers to run ARM-based Debian images over x86/x86_64 CPU's
would impact the way they could be more productive and for Debian to be
more adopted as development environment.
I can say that I'm very enthusiast of this opportunity and I'm
certain that the outcome will result in more adoption. Even the Ubuntu
people is now pushing more and more efforts for ARM official support,
due the facts I've stated.
1- http://lists.debian.org/debian-arm/2011/06/msg00020.html
2- http://events.linuxfoundation.org/events/android-builders-summit/back

Hello, this is the official project report for the Debian GSoC admins and everyone. It s been few days since the official coding phase started. Most of the time I ve been figuring out the details regarding integration of non-x86 images to the Eucalyptus IaaS and working on the ARM image, as you ll learn later. I m also in the process of starting to design the set of tools we ll be delivering as part of the project. The project s goal is to be a useful resource for Debian developers and porters. I ve joined some porters list in order to learn what are the things they are struggling with and how the project can help to address them. I ll be starting a wiki page with such topics. Bonding period:
Bonding period has been more fruitful than I expected. As mentioned in my previous post, Steffen and I got in touch with the Eucalyptus team, since they show their early interest on the project. We are coordinating cooperation between our teams. Besides my mentor and I defined to start working on the ARM image. Coordination went OK. We ll be having meetings every two weeks. Project Status:
Resuming Dominique s work I began working on the ARM image. Aur lien s work was a great resource. Currently I have a working and updated Debian testing ARM image using the versatile kernel that can be used under qemu-arm. I m currently making tests and figuring out the next phase which is cloudify it. Over this weekend I expect to finish on that side and then began on the design and implementation of the tools that will be the project s result.

Until now I haven t faced much issues, but the Eucalyptus part since the docs are targeting x86 and amd_64 archs. However I think I can run qemu-arm on top. I ll talk to them about the idea.

Future plans: week 3: - Finish tests with the ARM image. - Design the base tool-set, thinking integration with dpkg-buildpackage and qemubuilder. week 4-8: - Write the necessary code. mid-term evaluation. Other bits: Latest days have been quite busy for me, since I m still have to attend class, my semester ends in five weeks. This week was quite overwhelming with media , my University published an article (Spanish) about me and the program. I m the third student of the CS school participating in GSoC, in the past we had Gentoo Project and KDE students. Later, a local Cable TV program interview me on the same matter, it went fine. I managed to talk about Debian and what we do (we get free Advertising yay!) :) also about Google s Summer of Code program and invited students to participate both in FLOSS projects and the program. Still don t know if they have put it on air, I think it will be next week.

Next monday, I will by flying to Mumbai, India, to spend one semester studying computer science at the Indian Institute of Technology Bombay. Slowly, I m getting excited. I will write about this trip here, as I did for my Ghana travel, and upload pictures to my online photo album. If you are in Mumbai and interested in Debian, Haskell, Isabelle, GPG Keysigning or similar stuff, drop me a mail. And if you are at IITB, just come by, I ll be staying in hostel no. 13 (room number not known yet). Namaste!

During DebConf, I managed to squeeze out of the middle of everything for long enough to write a column, a short article for a participation I have every three months, for Mexican Software Gur magazine. All in all, I liked the resulting text The current number's main topic is alternative user interfaces. I find it sometimes hard to define what Software Gur 's audience is Probably, project leaders in software development; not the actual developers, but people who actually understand about coding... but care more about The Big Picture, Processes, Architecture Engineering and Buzzword Compliance. It is an interesting magazine, all in all, but with a focus and viewpoint I often feel myself not precisely comfortable with. So, if this trimester's topic was alternative user interfaces, I decided to write on the history and future of the man-machine interface (Spanish only) (version in the magazine's site). My viewpoint comes from the fact that I do not believe we are in a state of so great, innovative changes that everybody is trumpeting, and I'd rather get others to really think on whether user interfaces have gone different in the last decades. Yes, there are many changes, but in form rather than essence. Anyway, I shared this text with some friends. Some days later, when I was back in Mexico, Pooka/Alejandro Miranda lent me a very interesting book: Hacer clic: Hacia Una Sociosemiotica De Las Interacciones Digitales (Do click: Towards a Socio-semiotics of Digital Interaction (Cibercultura)), by Carlos Scolari. I am not yet even halfway through it, but I am enjoying it This book speaks, so far, about the meanings of interfaces, and of the history of interfaces themselves, even forgetting that nowadays we (mostly) refer to interfaces as what we have between the man and the machine. Sadly, I cannot find this book in English, as it is very well worth a read. But if the topic sounds interesting and you can understand the language, don't hesitate and pick up the book. It gives an interesting insight on the topic, for a group of people (us techies) used to looking at things in a much more human-cognitive-process-oriented way. [update] I found this nice overview of the "Hacer clic" book, written as a presentation for the book. It explains precisely the part I am currently reading - The four metafora for interaction: Conversational, instrumental, superficial and spatial.

Again, there's been this surreal time warp effect. 3 months has passed, and it feels like both a long time and a blink of an eye. It more feels like a long time though. I've mostly forgotten what it was like before Zoe came along. Zoe is growing well. She weighs around 11 lbs 11 oz (5.3 kg), and I swear she's getting very long. When I'm holding her in my arms, there's legs everywhere. She started being able to roll from her stomach onto her back at 2 months, and her neck strength is pretty good now. I guess her next significant milestone will be being able to sit up properly. When she's on her tummy, she can prop herself up on her elbows and look around. She smiles all the time. We had a few nights of 8 hours of sleep, then everything went completely out the window, and we had about a week of very disrupted sleep at night. I think she's starting to settle into a routine now though, with a few 5 hour stints the last few nights. Her US passport arrived yesterday. We still need to get everything together to lodge her Australian citizenship application, which is the first step towards getting her an Australian passport. Sarah's back studying now (two subjects this semester), which is proving to be a bit of a juggling act.

My project. This post assumes that the reader has read my last post. This week I had less time to work on my project than the last ones, because it was kind of the last week of the semester for some disciplines. This was unfortunate from a point of view, but it s good in another, because now I ve finished most of my disciplines and can focus more. This is also the reason why the weekly report is slightly delayed. Most of my work this week was continuing the investigation of the segfault caused by my implementation of allocation in lines. The most interesting thing I discovered came after a suggestion from my menthor: to use +RTS -DS to turn on the sanity checker. I runned the code with my allocation implementation and the sanity checker and got a segfault. I runned again only with the code to free memory in lines and I got also a segfault. Then I runned without all my patches, using sweep, and I got the segfault. So it seems that there is something wrong with sweep, and now I m investigating this new segfault. I m using the bernouilli program from nofib to test, running with 148 as a parameter and, naturally, +RTS -w -DS passed to the RunTime System. The output of gdb:

Current directory is /home/marcot/trabalho/livre/ghc/nofib/imaginary/bernouilli/
GNU gdb (GDB) 7.1-debian
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /home/marcot/trabalho/livre/ghc/nofib/imaginary/bernouilli/Main...done.
(gdb) r 148 +RTS -w -DS
Starting program: /home/marcot/trabalho/livre/ghc/nofib/imaginary/bernouilli/Main 148 +RTS -w -DS
[Thread debugging using libthread_db enabled]
Program received signal SIGSEGV, Segmentation fault.
0x00000000006309cb in LOOKS_LIKE_INFO_PTR_NOT_NULL (p=12297829382473034410) at includes/rts/storage/ClosureMacros.h:225
(gdb) where
#0  0x00000000006309cb in LOOKS_LIKE_INFO_PTR_NOT_NULL (p=12297829382473034410) at includes/rts/storage/ClosureMacros.h:225
#1  0x0000000000630a16 in LOOKS_LIKE_INFO_PTR (p=12297829382473034410) at includes/rts/storage/ClosureMacros.h:230
#2  0x0000000000630a4b in LOOKS_LIKE_CLOSURE_PTR (p=0x7ffff6c84062) at includes/rts/storage/ClosureMacros.h:235
#3  0x0000000000631427 in checkClosure (p=0x7ffff6853a08) at rts/sm/Sanity.c:320
#4  0x00000000006319ef in checkHeap (bd=0x7ffff68014c0) at rts/sm/Sanity.c:479
#5  0x000000000063222f in checkSanity (check_heap=rtsTrue) at rts/sm/Sanity.c:686
#6  0x000000000062dfdb in GarbageCollect (force_major_gc=rtsFalse, gc_type=0, cap=0x8d2ec0) at rts/sm/GC.c:768
#7  0x0000000000620431 in scheduleDoGC (cap=0x8d2ec0, task=0x8f5080, force_major=rtsFalse) at rts/Schedule.c:1420
#8  0x000000000061fa2c in schedule (initialCapability=0x8d2ec0, task=0x8f5080) at rts/Schedule.c:539
#9  0x0000000000620c77 in scheduleWaitThread (tso=0x7ffff6c80000, ret=0x0, cap=0x8d2ec0) at rts/Schedule.c:1902
#10 0x000000000065762b in rts_evalLazyIO (cap=0x8d2ec0, p=0x89d8b0, ret=0x0) at rts/RtsAPI.c:495
#11 0x000000000061d3db in real_main () at rts/RtsMain.c:66
#12 0x000000000061d4ca in hs_main (argc=5, argv=0x7fffffffe6d8, main_init=0x406558 <__stginit_ZCMain>, main_closure=0x89d8b0) at rts/RtsMain.c:115
#13 0x00007ffff6fbcabd in __libc_start_main (main=<value optimized out>, argc=<value optimized out>, ubp_av=<value optimized out>, init=<value optimized out>, fini=<value optimized out>, rtld_fini=<value optimized out>, stack_end=0x7fffffffe6c8) at libc-start.c:222
#14 0x0000000000403a69 in _start ()

I started the investigation with the most obvious test: to remove the call to sweep() in rts/sm/GC.c.

  if (major_gc && oldest_gen->mark)  
      if (oldest_gen->compact)
          compact(gct->scavenged_static_objects);
      // else
      //     sweep(oldest_gen);

The result was the same, same segfault in the same place. So I decided to do it a little stronger and avoid the blocks getting the BF_MARKED flag, so that they are not even marked.

                if (!(bd->flags & BF_FRAGMENTED))  
                    // bd->flags  = BF_MARKED;
                 

This one worked. The code in sweep() is not commented, but it s irrelevant, since it ignores blocks that don t have this flag. My third try was to comment the places where the BF_MARKED flag is read, to see each one was causing the segfault. I got a list of places to search with grep, and there weren t a lot of them.

$ grep BF_MARKED rts/sm/*.c
rts/sm/Compact.c:       if (bd->flags & BF_MARKED)
rts/sm/Evac.c:  if ((bd->flags & (BF_LARGE   BF_MARKED   BF_EVACUATED)) != 0)  
rts/sm/Evac.c:        if (bd->flags & BF_MARKED)  
rts/sm/GCAux.c:    if ((bd->flags & BF_MARKED) && is_marked((P_)q,bd))  
rts/sm/GC.c:                    if (!(bd->flags & BF_MARKED))
rts/sm/GC.c:                        // time, so reset the BF_MARKED flags.
rts/sm/GC.c:                        // compact.  (search for BF_MARKED above).
rts/sm/GC.c:                        bd->flags &= ~BF_MARKED;
rts/sm/GC.c:                // Also at this point we set the BF_MARKED flag
rts/sm/GC.c:                // BF_MARKED is always unset, except during GC
rts/sm/GC.c:                    bd->flags  = BF_MARKED;
rts/sm/Sweep.c:        if (!(bd->flags & BF_MARKED))  

The first one is in rts/sm/Compact.c, so it s not relevant to the use with -w. The second one, in rts/sm/Evac.c, is a bit indirect.

  if ((bd->flags & (BF_LARGE   BF_MARKED   BF_EVACUATED)) != 0)  
      // pointer into to-space: just return it.  It might be a pointer
      // into a generation that we aren't collecting (> N), or it
      // might just be a pointer into to-space.  The latter doesn't
      // happen often, but allowing it makes certain things a bit
      // easier; e.g. scavenging an object is idempotent, so it's OK to
      // have an object on the mutable list multiple times.
      if (bd->flags & BF_EVACUATED)  
          // We aren't copying this object, so we have to check
          // whether it is already in the target generation.  (this is
          // the write barrier).
	  if (bd->gen < gct->evac_gen)  
	      gct->failed_to_evac = rtsTrue;
	      TICK_GC_FAILED_PROMOTION();
	   
	  return;
       
      /* evacuate large objects by re-linking them onto a different list.
       */
      if (bd->flags & BF_LARGE)  
	  info = get_itbl(q);
	  if (info->type == TSO &&
	      ((StgTSO *)q)->what_next == ThreadRelocated)  
	      q = (StgClosure *)((StgTSO *)q)->_link;
              *p = q;
	      goto loop;
	   
	  evacuate_large((P_)q);
	  return;
       
      /* If the object is in a gen that we're compacting, then we
       * need to use an alternative evacuate procedure.
       */
      if (!is_marked((P_)q,bd))  
          mark((P_)q,bd);
          push_mark_stack((P_)q);
       
      return;
   

The first if, in line 466, is executed if any of the three flags is present: BF_LARGE, BF_MARKED or BF_EVACUATED. The second if, in line 474, checks for BF_EVACUATED, and returns. The third if, in line 487, checks for BF_LARGE and returns. The code in lines 502-505 is only executed if BF_MARKED is present, and not the other ones. I tried commenting this code, and got an assertion fail in the user code, so I think this is not a good path to follow. The second occurence of BF_MARKED is in the same file.

        if (bd->flags & BF_MARKED)  
            // must call evacuate() to mark this closure if evac==rtsTrue
            *q = (StgClosure *)p;
            if (evac) evacuate(q);
            unchain_thunk_selectors(prev_thunk_selector, (StgClosure *)p);
            return;
         

Commenting it, with or without the call to sweep() commented, causes the same segfault. So, I m tending to think this part of the code is unrelated to the issue. The third occurence is in rts/sm/GCAux.c. I tried commenting it with all the four combinations of the two others commented and not commented, and all resulted in the segfault in the same place. There s another place to check in rts/sm/GC.c. Again, commenting it made no difference. The last one is part of sweep(), so it s avoided anyway when the call to this function is commented.

The world around me seems to whirl these days. One week ago, I graduated from MIT. People I've known during the last four years have been dispelling to various parts of the globe one by one, day by day. California, Canada, Indonesia, Seattle. Some will be back again. Some will not, or if so only to visit. pika is a continuous bustle of activity as the summer has commenced and it has filled with creative and adventurous MIT students who've suddenly found themselves having free time. A hammock being built on the roofdeck. Thrice-weekly icecream forays. Common areas overflowing with people playing musical instruments, chatting, and messing around on laptops. Summer's warmth has arrived, bringing with it farmer's markets, strawberry picking, and swimming expeditions. While it's wonderful to get to meet so many new people living in a college environment, I can't help but feel sadness thinking about everyone who's left. There are always more friends to be made as new people arrive, but old ones moving away leave bittersweet memories, and the new relationships are always a bit different as the age discrepancy between me and others changes. Or the me-the-ephemeral-collection-of-thoughts-which-when-regarding-other-people-sometimes-involve-the-mentor/mentee-distinctions-caused-by-one-party-being-older-or-more-knowledgeable-than-the-other-at-least-in-certain-areas changes. The end of a semester always feels like this, but this year even more so as the people I started university with start down new paths. For me, that was going to involve staying on at MIT to complete a one-year master's program, the "M.Eng." in electrical engineering and computer science. That plan, too, has changed. I've deferred the degree and accepted a full-time engineering position at Ksplice, an exciting early-stage Linux startup here in Cambridge. I'd been working at Ksplice part-time since January before joining full-time immediately following graduation. Ksplice is the realization of ideas I saw being born on the whiteboard at SIPB when I was a freshman, and it's fun to see that play out in a small, ever-changing, low-bullshit company. All in all, there are many more exciting things down the road, and, working at an MIT startup, I haven't even escaped the MIT/Cambridge reality-distortion bubble yet. Still, it's tempting to resist change and let myself romanticize the good old days, hoping to catch every person I've ever enjoyed spending time with and hold them down here forever. That's not the way life works, though. Change happens.

Hello all.

Last week I was very busy, due to my university duties. On Tuesday I had my first exam in this semester (in Numerical Analysis), which took me more time than I had thought it would be.
From this reason my project is slightly behind schedule, but now I will do my best to catch the plan.

On the other hand, there are also some good news for me. Some time ago, Daniel Burrows migrated aptitude repository from mercurial to GIT. I am git user for nearly year, so I strongly support this move ;) .

Here are some basic thoughts which functionalities good package manager must have (and which approach (from aptitude-gtk, synaptic and adept) I like the most):

• upgrade packeges with good conflict resolution - aptitude conflict resolver is the most advanced. Without a doubt, it has to be in Qt version
• fast searching and installing new packages - I prefer synaptic/yast approach with categories on the left and packages on the right, with single click behavior from KPackegeKit/adept (single click shows package description under selected package and with detailed informations available in new tab - as in aptitude-gtk)
• viewing detailed package informations
• downgrading, holding etc
• fetching packages list, cleaning cache etc

All of this will be elaborated in mockups. Am I forgetting something important?

The most important questions is: "What is the most common use case for package manager? Installing packages or upgrading packages?". I am not sure if this two actions require different views, or there should be only new category in install package view.

This is all now. More updates (and mockups) will be available today's midnight (or tomorrow morning). So please stay tuned :)

I opened Slashdot's Looking back from the 1980s at computers in education article because I am quite convinced of the point some of the commenters argued before me, (and it's good to know others think as you do ;-) ) When I got close to computers, learning computing for children basically meant learning programming in a fun way. For years, my hobbies included Logo and BASIC. At age 7 (by 1983), typing TeX and using Emacs at the computer of the institute where my father worked, I started walking the path I took for my professional life. When I taught computing to high school students as my first paid job (which didn't last long, only a semester, as for an untrained 20 year old it is very hard to control a group of kids nearly his age), I tried to teach some basic BASIC programming (which was the best I knew then)... But no, both students and the school wanted me to focus on teaching MS Office applications. It seemed stupid for me 14 years ago, and it still seems stupid for me today. Anyway, on Slashdot, I came across this beautiful way to explain what computer education should mean:

"computing is no longer taught in schools (parents look quizzical), they are simply 'trained' (parents look like they vaguely get it). if this was sex instead of computing that was taught in schools, would you prefer that your kids have sex _education_ or sex _training_? (parents finally get it)".

By the way, if you are interested in reading a bit of paleofuturism, to feel the joy and excitement with which computer-aided education was seen 30 years ago, be sure to get the Classroom Computer News issue for September-October 1980, linked from the Slashdot article (and copied over here for your convenience, of course!)

Attachment	Size
Classroom Computer News vol. 1 no. 1, sep-oct 1980	3.54 MB

Sarah got a piece of mail today from USQ, with a very ominous "Do Not Bend" on it. It turns out because she averaged a 6.5 GPA in semester 2, she'd qualified for a special Dean's Award for Outstanding Academic Achievement, and will get a mention on the University's website and in a bunch of newspapers. I'm really proud of her. Unfortunately, she had to withdraw from semester 3 (the Summer semester) study because all of the baby's brain stuff came up right towards the end of semester, and that on top of moving and trying to renovate was just too much for her. She's intending to take Semester 1 off, because the baby's due right around exam time, and then resuming study in Semester 2.

Kiwis have to be one of the cutest birds of all time. A bit chubby and clumsy looking, they are (to me, at least), walking, breathing icon of furry cuteness. Truth be told, I did not see one live in action during my recent trip to New Zealand, but I did see a Weka bird which is pretty similar. (Micah and I just consulted the Internets and agreed that we did in fact see cherubic Kiwi not a Weka. In fact, Micah almost ran one over on the west coast of the southern island but his quick reflexes born from years of saving servers while typing saved the bird. So as you can tell by now I finally got to go to New Zealand for a few weeks, even able to travel the south island before attending THE Linux conference of the region, LCA where I gave a talk (video to be posted when available). I jumped at the opportunity and was thrilled to find out that I could actually spend some time traveling around before the intense week long conference. So on January 5th I headed down with Micah to what I have found out is one of the windiest cities on earth ( Windy Wellington ) for a few days before heading to the south island to do a loop on the northern half of the island. I wanted to conquer the mountains made famous by a certain set of movies, but last semester was all about sitting in front of the computer, a sort of agonizing life of the mind, which did not prepare me physically for mountain trekking or as it call it there, tramping. So we decided to stick close to the coast (with one transalpine train that serenaded us through some awesome mountain passes) and hike along the coast, snorkel and swim, and kayak. After Andrew showed us around Wellington, we headed to the sea town of Kaikoura brimming with sea life, such as seals, dolphins, and birds. The two highlights there were our snorkeling trip and a hike along the peninsula. Originally we were going to go diving but I arrived to NZ with a head cold so we opted for the sinus friendlier version and snorkeled in the massive kelp forest, which was strikingly beautiful (I am used to tropical reefs and waters). There happened to be a lot of seals and given their curious nature, they would dart over right next to you and play. One seal I called him the twirler was chubby and mellow and twirled next to me for a long while. The lady seals were sleeker and faster and liked to dive deep down and the zoom up and surprise you. As someone who has spent a lot of time underwater, I found it fun and weird to be with animals that pay attention to you given that most of the sea life ignores you. The hike in Kaikoura was fantastic as well. You go high on a bluff and stare down at this water sparkling with the most beautiful blue hues brought out even more majestically by the white rocks. If I were to go back I would hike along the water and up above on the bluff. After a brief stopover in Christchurch to visit a friend, we took the transalpine train (across Arthur s pass) which was superbly beautiful and arrived on the west coast whose seas are far more rough, rocky, andtemperamental than on the east coast. The vegetation is lush as lush can be and you get the feeling that dinosaurs would have been a happy lot in these parts. The cool part about this area are the many rivers that feed into the ocean (we spent an afternoon swimming and exploring the caves in one) and then what are called the pancake rocks, which are odd geological creatures that really amaze. We then made our way to the Marlborough Sounds area, which includes the city of Nelson (apparently the sunniest in New Zealand) as well as many olive and grape vineyards in outlying areas. We spent some time in the Alpine lakes region hiking but more of the time on the coast. The highlight for me and it is a place I would love to go back to is the Abel Tasman National Park. We spent time hiking and kayaking there and you can even hike down the coast for 5-6 days (there are excellent camping facilities along the way). The coast is simply majestic with alpine like forest conditions (unfortunately a cool old tree whose name I can t remember is no longer common). This forest is situated along the most stunning waters, an electric but totally clear turquoise blue deceivingly inviting because the water was quite cold (but not as cold as the Oregon coast over the summer, which I went swimming in only once after weeks of bike travel). Along with the blue, parts of the coastal waters were a stunning clear green that I have never seen despite my many sea travels. If you ever plan on going to the South Island, I would not miss this area and might even try to spend a few days or more hiking the coastal trails and listening to the cool-as/sweet as birds, one of which has double vocal cords so it sings what sounds to be like totally electronic bird calls. We returned via the same ferry a massive 7 story ship from Picton to Wellington but the conditions were far far worse during our return trip. When we got out of the sounds, we hit the Cook Straight, notorious for being rough and tumble. And indeed, once we hit the waves, I felt like I was no longer in a boat but amusement park ride, the bow of the ship thrown high only to fall hard on upon the waves. It was sort of fun or fun for about 10 minutes until people, most especially kids, started yaking all over the place. It was really the most flagrant yakfest I have ever experienced (I mean it is a 7 story ferry, you can fit a lot of people on that boat) and that made the sail particularly difficult. I have pretty strong sea legs, never once getting sick sick during the year I spent at sea but massive yaking will bring out the sea sick feeling in even the hardiest of sea souls and I was thrilled to arrive in Wellington. Wellington is the only large city I spent any considerable time in and it is a pretty awesome one. The city center area is flat and by the water, with a magnificent area filled with museums, the national library, parks, breweries, and piers where kids like to jump off high things. The botanical gardens were the most beautiful I have been to and since I am a flower nut, I was in high heaven. In this area there are a ridiculous number of great coffee shops (NYC has a thing or two to learn as we don t have enough, I suspect it has something to do with insane real estate prices). The city is surrounded by hills populated by houses, some of the precipitously perched on cliffs that require lifts to get to! It was a wonderful home base for what was a sweet as conference (as they would say down there). And I hope to write about it sometime soon.

Kiwis have to be one of the cutest birds of all time. A bit chubby and clumsy looking, they are (to me, at least), walking, breathing icon of furry cuteness. Truth be told, I did not see one live in action during my recent trip to New Zealand, but I did see a Weka bird which is pretty similar. (Micah and I just consulted the Internets and agreed that we did in fact see cherubic Kiwi not a Weka. In fact, Micah almost ran one over on the west coast of the southern island but his quick reflexes born from years of saving servers while typing saved the bird. So as you can tell by now I finally got to go to New Zealand for a few weeks, even able to travel the south island before attending THE Linux conference of the region, LCA where I gave a talk (video to be posted when available). I jumped at the opportunity and was thrilled to find out that I could actually spend some time traveling around before the intense week long conference. So on January 5th I headed down with Micah to what I have found out is one of the windiest cities on earth ( Windy Wellington ) for a few days before heading to the south island to do a loop on the northern half of the island. I wanted to conquer the mountains made famous by a certain set of movies, but last semester was all about sitting in front of the computer, a sort of agonizing life of the mind, which did not prepare me physically for mountain trekking or as it call it there, tramping. So we decided to stick close to the coast (with one transalpine train that serenaded us through some awesome mountain passes) and hike along the coast, snorkel and swim, and kayak. After Andrew showed us around Wellington, we headed to the sea town of Kaikoura brimming with sea life, such as seals, dolphins, and birds. The two highlights there were our snorkeling trip and a hike along the peninsula. Originally we were going to go diving but I arrived to NZ with a head cold so we opted for the sinus friendlier version and snorkeled in the massive kelp forest, which was strikingly beautiful (I am used to tropical reefs and waters). There happened to be a lot of seals and given their curious nature, they would dart over right next to you and play. One seal I called him the twirler was chubby and mellow and twirled next to me for a long while. The lady seals were sleeker and faster and liked to dive deep down and the zoom up and surprise you. As someone who has spent a lot of time underwater, I found it fun and weird to be with animals that pay attention to you given that most of the sea life ignores you. The hike in Kaikoura was fantastic as well. You go high on a bluff and stare down at this water sparkling with the most beautiful blue hues brought out even more majestically by the white rocks. If I were to go back I would hike along the water and up above on the bluff. After a brief stopover in Christchurch to visit a friend, we took the transalpine train (across Arthur s pass) which was superbly beautiful and arrived on the west coast whose seas are far more rough, rocky, andtemperamental than on the east coast. The vegetation is lush as lush can be and you get the feeling that dinosaurs would have been a happy lot in these parts. The cool part about this area are the many rivers that feed into the ocean (we spent an afternoon swimming and exploring the caves in one) and then what are called the pancake rocks, which are odd geological creatures that really amaze. We then made our way to the Marlborough Sounds area, which includes the city of Nelson (apparently the sunniest in New Zealand) as well as many olive and grape vineyards in outlying areas. We spent some time in the Alpine lakes region hiking but more of the time on the coast. The highlight for me and it is a place I would love to go back to is the Abel Tasman National Park. We spent time hiking and kayaking there and you can even hike down the coast for 5-6 days (there are excellent camping facilities along the way). The coast is simply majestic with alpine like forest conditions (unfortunately a cool old tree whose name I can t remember is no longer common). This forest is situated along the most stunning waters, an electric but totally clear turquoise blue deceivingly inviting because the water was quite cold (but not as cold as the Oregon coast over the summer, which I went swimming in only once after weeks of bike travel). Along with the blue, parts of the coastal waters were a stunning clear green that I have never seen despite my many sea travels. If you ever plan on going to the South Island, I would not miss this area and might even try to spend a few days or more hiking the coastal trails and listening to the cool-as/sweet as birds, one of which has double vocal cords so it sings what sounds to be like totally electronic bird calls. We returned via the same ferry a massive 7 story ship from Picton to Wellington but the conditions were far far worse during our return trip. When we got out of the sounds, we hit the Cook Straight, notorious for being rough and tumble. And indeed, once we hit the waves, I felt like I was no longer in a boat but amusement park ride, the bow of the ship thrown high only to fall hard on upon the waves. It was sort of fun or fun for about 10 minutes until people, most especially kids, started yaking all over the place. It was really the most flagrant yakfest I have ever experienced (I mean it is a 7 story ferry, you can fit a lot of people on that boat) and that made the sail particularly difficult. I have pretty strong sea legs, never once getting sick sick during the year I spent at sea but massive yaking will bring out the sea sick feeling in even the hardiest of sea souls and I was thrilled to arrive in Wellington. Wellington is the only large city I spent any considerable time in and it is a pretty awesome one. The city center area is flat and by the water, with a magnificent area filled with museums, the national library, parks, breweries, and piers where kids like to jump off high things. The botanical gardens were the most beautiful I have been to and since I am a flower nut, I was in high heaven. In this area there are a ridiculous number of great coffee shops (NYC has a thing or two to learn as we don t have enough, I suspect it has something to do with insane real estate prices). The city is surrounded by hills populated by houses, some of the precipitously perched on cliffs that require lifts to get to! It was a wonderful home base for what was a sweet as conference (as they would say down there). And I hope to write about it sometime soon.

Fall semester I did not teach any classes that covered digital media (in part because I was swimming in the stuff writing a review essay on the topic, which I am sending today to the journal, ending about 4 months of hell). On the other hand, spring semester will be all about digital media: hackers, free software, privacy, piracy, phone phreaking and more. I am excited. Here is my graduate syllabus on the commons and piracy and here is my undergraduate class on hacking. Both are still under development but pretty far along.

Fall semester I did not teach any classes that covered digital media (in part because I was swimming in the stuff writing a review essay on the topic, which I am sending today to the journal, ending about 4 months of hell). On the other hand, spring semester will be all about digital media: hackers, free software, privacy, piracy, phone phreaking and more. I am excited. Here is my graduate syllabus on the commons and piracy and here is my undergraduate class on hacking. Both are still under development but pretty far along.

I guess I ve never been one to do things a certain way just because that s how they re normally done. I took my first college class pretty young, back in 1995, just after my freshman year in high school. By the time of my junior year in high school, I was well on my way through the computer science curriculum at Wichita State, and would probably have graduated from WSU at about age 20 had I not moved to Dallas, and then Indianapolis, for jobs. I did so because I (correctly) thought that in my line of work, experience was more important than a degree. However, playing into that was the incorrect notion that an education was useful primarily as a means to a career a notion that colleges and universities unfortunately have been promoting themselves. After moving back to Kansas, I started work to finish my degree I had effectively one year left had I been a full-time student. But it was difficult doing so, living almost an hour from Wichita, having a full-time job, and then when Jacob was on the way, I stopped classes entirely. Having online classes available to help me finish out the degree has been great. A year ago, I re-thought the value of education to me, concluding that there is a lot of value in education for its own sake. Looking at education as little more than a means to a career is the wrong way to approach it. Since I have had that re-evaluation, I ve adjusted my path even at this late point, and have enjoyed my classes more than I ever had before because of it. Graduating! So anyhow, here I am, graduating in a few days, 14 years after I started. I ve had some good news this semester, too: I ll pass the requirements to be a graduate of the WSU honors program, and also to graduate magna cum laude. So it may have taken me 14 years to do finish college, but at least I ve done it well . It feels weird to be about to be done with college, after so many years of being almost done, except for And a question I ve been thinking about a lot is: What next? Obviously I ll start by taking a break from college stuff. I want to be able to spend more time with Terah, Oliver, and Jacob, and there are things around the house that need attention. But after that? I figure I have a few options: No more college, but some reading. I do enjoy reading, and especially reading older works that are nicely out of copyright and thus free. I ve read few of the classics, but I enjoy reading them, and want to be better informed about them too. That could be fun. But sometimes it s hard to know how to place things in context. For instance, I don t think I could have gotten as much out of reading some famous philosophers as I did by doing so in a class that put them all in context and discussed criticisms of different positions. I also wouldn t necessarily have the ability to discuss and debate ideas with my classmates. Take the occasional undergraduate class in a topic that interests me. I m especially interested in history and literature, and haven t had much exposure at the college level in either. Various online courses are available from universities in Kansas on those topics. I could take a course or two each year and become a better-informed, more well-rounded person, and study an interesting topic at the same time. Maybe this would eventually lead to a degree, and maybe not. It would be fine either way. Graduate studies. It s a lot of work, and I m not sure it would be all that interesting to me. I ve looked some at curricula. I don t think that I m interested in computer science as a graduate program; I enjoy coding more than theorizing and analysis. But I also don t think that a graduate MIS or some such degree is for me; most of them appear to either focus on Windows or cover things that I ve already known how to do for years, and thus I wonder just what the point of them is (in addition to questioning how rigorous the curriculum is). I could also, down the road, pursue a graduate degree in something like English, philosophy, or history, but it seems a natural path to that would be to take more undergraduate classes in those topics first. So for now, I ll sit tight. I ll see how I feel by summer, how pressed for time I feel at home, and if I still feel the desire to take more classes. If so, I suspect I ll try to take some undergraduate classes in whatever sounds interesting to me at the time. In a way, that is quite freeing take a class on whatever topic I like, without a defined degree in mind. I ve never been free to do that before, and I like the idea of it.