Yesterday was my 21st birthday, and I received all “Hitchhiker’s Guide to the Galaxy” novels, the five ones in one book, and the sixth one written by Eoin Colfer in another book. Needless to say, the first book weights more than an N900. I did not read them yet, so now is the perfect chance to do so. Yes, I did not know that 25th is towel day, sorry for that. ... Read more 》

I did not write much code or merge much of my prototype code, but some things happened since the last blog post about APT2 specific things in August and I forgot to write about them. First of all, I dropped the GVariant-based cache. The format strings were simply getting ugly long and were not very understandable, performance was just much too slow (needing more than a few nanoseconds for a package lookup is obviously too slow for solving dependency problems); furthermore, building the cache was also slow and complicated because we needed all attributes of an object at once to pass them to GVariant, leading to ugly API. ... Read more 》

As everyone should know, underscores in C are not cool, as they cause undefined behavior per 7.1.3: Yet, they are widely used everywhere. Here are some examples: * inclusion guards in GLib: ` __G_VARIANT_H__` * internal Python functions: `_PyUnicode_AsString` * various macros in APT: `__deprecated`, `__hot` All of this triggers undefined behavior and is thus uncool. Of course in APT, it’s most stupid, as we do not have any namespace and could thus end up redefining things we should not much more likely then the other two. ... Read more 》

The last two weeks, two new python-apt releases were made. 0.8.0exp3 did not add much, but 0.8.0exp4 added some new bindings for our friends at the mancoosi project. I also committed several fixes to the APT repository, but did not upload them yet. In #debian-devel, some people (including me and others on the Debian side; and sladen, sabdfl for the Ubuntu side) discussed the Ubuntu font license which is considered non-free by Debian, due to extreme naming restrictions in section 2 (unmodified versions must keep the name, slightly modified versions must keep the name and add something). Some consider those restrictions equivalent to invariant sections. After we discusses the font license, we quickly got to discuss Doctor Who and time travel, as those two are obviously connected. ... Read more 》

python-apt 0.8.0~exp2 bug fix release On Tuesday, I uploaded python-apt 0.8.0~exp2 to experimental, fixing about 10 bugs reported in Ubuntu and Debian bug trackers. It should know even convert integers correctly on all architectures, previously we could have passed long via varargs where int was expected. Bugs Until Thursday, I went through the bug list in Launchpad and closed/fixed/reassigned/merged about 100 bugs in APT and python-apt. APT & python-apt updates for squeeze Today, I uploaded updates of apt and python-apt to stable. They include support for xz and parsing multi-arch dependencies, as wanted by ftpmasters. ... Read more 》

Internship / APT stuff This week was a rather busy week. I’m currently doing a (unpaid) 1 month internship as part of my education. Thanks to Michael Vogt and his boss at Canonical Ltd, this internship takes place in IRC and is dedicated to Debian and Ubuntu stuff, primarily APT-related things. The first two days were spent on multi-arch support in python-apt: On Monday, I released python-apt 0.7.100.3, introducing initial minimal multi-arch support (just enough to not break anymore, but no really new multi-arch-specific API). This release is also the base for the version going to be shipped in Ubuntu natty, which is one of the reasons to keep the changes such minimal. I also fixed an RC bug related to Python 3.2 modules in python-apt, and implemented nocheck build option and disabled test errors on hurd. ... Read more 》

As some already know, is that I use sbuild to build all my packages in clean chroot environments. For this, I use the ‘aufs’ “mode” of schroot, that allows you to setup a chroot with one read-only base directory and one writeable overlay where changes are written to. One thing I had problems with was the time required to install build dependencies due to disk I/O. Given that I have 4G RAM in my computer, I decided to use a tmpfs as the writable overlay. For those of you who want to do the same, putting the following in /etc/fstab makes it work: ... Read more 》

Vettel made it - F1 World Champion 2010.

The following program, compiled with clang 1.1, runs 500 times faster than the gcc4.5-compiled code (in both cases with -O2): <span style="color:#008200;">#include <stdio.h></span> <span style="color:#008200;">#define len 1000000000L</span> <span style="color:#830000;">unsigned long</span> <span style="color:#010181;">f</span><span style="color:#000000;">(</span><span style="color:#830000;">unsigned long</span> a<span style="color:#000000;">,</span> <span style="color:#830000;">unsigned long</span> b<span style="color:#000000;">)</span> <span style="color:#010181;">__attribute__</span><span style="color:#000000;">((</span>noinline<span style="color:#000000;">));</span> <span style="color:#830000;">int</span> <span style="color:#010181;">main</span><span style="color:#000000;">()</span> <span style="color:#000000;">{</span> <span style="color:#010181;">printf</span><span style="color:#000000;">(</span><span style="color:#ff0000;">"%lu</span><span style="color:#ff00ff;">\n</span><span style="color:#ff0000;">"</span><span style="color:#000000;">,</span> <span style="color:#010181;">f</span><span style="color:#000000;">(</span><span style="color:#2928ff;">0</span><span style="color:#000000;">,</span> <span style="color:#2928ff;">2</span><span style="color:#000000;">*</span>len<span style="color:#000000;">));</span> <span style="color:#000000;font-weight:bold;">return</span> <span style="color:#2928ff;">0</span><span style="color:#000000;">;</span> <span style="color:#000000;">}</span> <span style="color:#830000;">unsigned long</span> <span style="color:#010181;">f</span><span style="color:#000000;">(</span><span style="color:#830000;">unsigned long</span> a<span style="color:#000000;">,</span> <span style="color:#830000;">unsigned long</span> b<span style="color:#000000;">)</span> <span style="color:#000000;">{</span> <span style="color:#830000;">unsigned long</span> sum <span style="color:#000000;">=</span> <span style="color:#2928ff;">0</span><span style="color:#000000;">;</span> <span style="color:#000000;font-weight:bold;">for</span> <span style="color:#000000;">(;</span> a <span style="color:#000000;"><</span> b<span style="color:#000000;">;</span> a<span style="color:#000000;">++)</span> sum <span style="color:#000000;">+=</span> a<span style="color:#000000;">;</span> <span style="color:#000000;font-weight:bold;">return</span> sum<span style="color:#000000;">;</span> <span style="color:#000000;">}</span> Now, I would be interested to see what’s happening here. I took a look at the assembler code both compilers create, but the only thing I found out so far is that gcc’s assembly is easier to understand - 50 lines (gcc) vs 134 lines (clang). If someone knows the answer, please tell me. ... Read more 》

Today, I got an email from an user of one of my Python scripts asking why the script t does not work on Arch Linux anymore. As it turns out, the Arch Linux team decided to switch /usr/bin/python to Python 3.0 and use python2 for Python 2.X versions. By doing this, they decided to make their distribution incompatible to almost any Python script in the world. Arch Linux’s decision to diverge from the rest of the world that uses python for Python 2.X and python3 for Python 3.X is stupid. And doing this without updating reverse dependencies beforehand and thus breaking packages in their own distribution is insane. In the end this means that if you use Arch Linux, you should consider switching to a distribution that does things the right way: Debian. You can also switch to Ubuntu, that’s normally just a bit less right (= faster). But using a distribution that does those crazy things in such an irresponsible way is really insane. ... Read more 》