Politreco

Lazy libkmod compression library loading

Lucas De Marchi — Mon, 03 Mar 2025 10:00:00 -0800

One new feature in kmod 34 is related to lazily loading the decompression libraries. In other words, dlopen them when/if they are needed. Although it’s desired for a tool like modinfo to be able to inspect a .ko.xz, .ko.zst or .ko.gz module, other daemons linking to libkmod would benefit from never loading them. This is the case for systemd-udevd that will load the kernel modules during boot when they are requested by the kernel.

Testing on Archlinux, it goes from this:

$ cat /proc/$(pidof systemd-udevd)/maps | grep -e libz -e liblzma
7f27a9ae8000-7f27a9aeb000 r--p 00000000 00 …

Linux module dependencies

Lucas De Marchi — Tue, 13 Aug 2024 10:00:00 -0700

With the imminent release of kmod 33, I thought it’d be good to have a post about the different types of module dependencies that we have in the Linux kernel and kmod. The new version adds another type, weak dependency, and as the name implies, is the weakest of all. But let’s revisit what are the other types first.

Hard (symbol) dependency

This is the first dependency that every appeared in kmod (and module-init-tools). A hard (or as some call, “symbol”) dependency occurs when your module calls or uses an exported symbol of another module. The most common …

Tracepoints and kernel modules

Lucas De Marchi — Tue, 15 Mar 2022 10:00:00 -0700

While debugging, it’s invaluable to be able to trace functions in the Linux kernel. There are several tools for that task: perf, ftrace (with helper tool like trace-cmd), bpftrace, etc.

For my own debug of kernel internals and in the last few years to debug the i915 module for Intel graphics, I usually use tracepoints or dynamic tracepoints (with perf probe) as the trigger for something I want to trace.

One question I get some times is “how do I trace the initial probe of a kernel module?”. At that time you (usually) don’t yet have the module …

Side-load on embedded Linux with Buildroot

Lucas De Marchi — Sun, 22 Sep 2019 10:00:00 -0700

Embedded Linux boards and devices often come with a shortage of tools installed. Often enough they don’t use a “normal” Linux distribution that can be easily extended by the end user by means of installing additional packages via dnf, apt, pacman, etc. Old/ancient versions of the Linux kernel is also very common.

In my previous post I wrote about using evemu to record data coming from the input subsytem and replay it on my computer in order to develop a Remote Controller software for ArduPilot. Without surprise, evemu isn’t included in the tools that come with Disco …

Using evemu to simulate input devices

Lucas De Marchi — Tue, 30 Apr 2019 01:15:00 -0700

I’m doing some experiments to make the remote controller of Parrot’s Disco drone (SkyController 2) to work with ArduPilot. I will talk more about this in another post. This one is basically about a nifty tool I’ve found that I didn’t know existed: evemu. I always used evtest to debug the input system in Linux.

SkyController 2 runs Linux and exposes all the sticks and buttons as an evdev device. I developed a tool to serve as a general-purpose software to be used in this kind of device: dema-rc. Ultimate goal is to have a software …

Per-project configuration for vim

Lucas De Marchi — Wed, 03 Apr 2019 21:57:00 -0700

For a long time I have accumulated different configurations for vim for the different open source projects I’m contributing or have contributed in the past. It became a giant unmaintained file for ftplugin/ftdetect with regexes to match the dir name and try to apply every important thing a project needs: from coding style to commands to build the source code.

After changing my machine and re-installing several softwares, I’m trying to keep my dotfiles more organized. For vim, after looking at some options available I settled in this one, that I think is very short and elegant …

git helper for “recursive rebase”

Lucas De Marchi — Tue, 26 Mar 2019 10:57:00 -0700

Very often I’m in the middle of an interactive rebase and while editing a commit I remember I should have changed a commit that I initially didn’t mark on the rebase todo. If you tried to git-rebase again you would notice it’s not possible due to git’s bookkeeping of the current rebase.

In the past what I usually did was to either 1) Continue the rebase and then rebase again to fix the previous commit or 2) Create a fixup commit with git commit --fixup and then rebase again with --auto-squash.

Now I have a helper …

“Throw away” linux images in seconds

Lucas De Marchi — Mon, 10 Aug 2015 12:44:00 -0700

Generating a new rootfs from scratch in order to test changes to early parts of the software stack or just to have a pristine environment is something I needed several times in the past.

Since I use Archlinux in my desktop something that I like is to have a similar environment in the target test rootfs. I decided to re-use and improve a script from Kay Sievers to create an installer that can be booted as a VM, as a container or in bare metal: arch-installer.sh. Originally it was a script to bootstrap a Fedora image and I think …

Taking maintainership of dolt

Lucas De Marchi — Mon, 09 Mar 2015 19:27:00 -0700

For those who don’t know, dolt is a wrapper and replacement for libtool on sane systems that don’t need it at all. It was created some years ago by Josh Triplett to overcome the slowness of libtool.

Nowadays libtool should be much faster so the necessity for dolt should not be as big anymore. However as can be seen here, it’s not true (at least in libtool > 2.4.2). Yeah, this seems a bug in libtool that should be fixed. However I don’t like it being any more complicated than it should.

After talking to …

Hacking the Intel fan, for fun

Lucas De Marchi — Tue, 01 Oct 2013 17:43:00 -0700

An alternative headline is: “how to show your wife how much you love her, the geek way”.

From 17 to 22 of September I was in New Orleans participating in the discussions of the Linux Plumbers Conference, which has already turned into one of my favorite conferences. Lots of fun, talking to great people and good discussions about systemd, containers, cgroups, kernel modules, etc. However as the headline indicates this blog post is not to talk about the conference but rather about a toy the Intel booth was giving out: a fan with 7 leds in its propeller. See below …

Optimizing hash table with kmod as testbed

Lucas De Marchi — Wed, 25 Sep 2013 07:32:00 -0700

One thing that caught my interest lately was the implementation of hash tables, particularly the algorithms we are currently using for calculating the hash value. In kmod we use Paul Hsieh’s hash function, self entitled superfast hash. I fell troubled with anything that entitles itself as super fast, especially given the benchmarks provided are from some years ago, with older CPUs.

After some time spent on benchmarking and researching I realized there were much more things to look after than just the hash function. With this post I try to summarize my findings, showing some numbers. However do take …

Speeding up build on autofoo projects

Lucas De Marchi — Mon, 19 Nov 2012 14:23:00 -0800

First of all, a little digression about build systems.

I’d like to clarify that I’m no lover of autotools. But I’m no lover of any other build system, neither, and autotools is used on several open source projects, including most of the ones I participate. It’s easily copied and pasted by new projects. It’s known by distro maintainers how to hack on it to work on different scenarios like cross-compilation, distribute build across machines, different compilers, rpath, etc etc. Moreover, from my experience, project maintainers usually dislike changing the build system because it causes several …

Analyzing chess.com tournaments

Lucas De Marchi — Tue, 16 Oct 2012 19:54:00 -0700

This year at ProFUSION we started to create chess tournaments to play using chess.com so we have fun not only coding but playing this game. However it’s even more fun when we put both together: chess and code :-)!

During the second tournament we realized chess.com was missing a nice feature: to allow participants to predict who would be the champion based on the current championship status and future results. To show the current state, Chess.com presents us with a table like this:

Not the missing games with a “_”. What we would like is to predict …

Back from Linux Plumbers

Lucas De Marchi — Mon, 03 Sep 2012 18:29:00 -0700

I’m back from USA after one week attending Linux Plumbers Conference. This was my first time in LPC, in which I was part of the CoreOS, talking about “From libabc to libkmod: writing core libraries”.

It was a very good experience and I’m glad to meet so many developers, both kernel and userspace hackers. Some of them I only knew from IRC, mailing-lists, etc and it was great time to share our experiences, discuss the current problems in Linux and even fix bugs :-). We seem finally to have reached a consensus on how module signing should be done …

ConnMan in Archlinux

Lucas De Marchi — Tue, 28 Aug 2012 23:37:00 -0700

For sometime (I think it’s almost 2 years) I was maintaining the ConnMan package in AUR, the user repository in Archlinux.

After talking to Dave Falconindy and Daniel Wallace, the later accepted to maintain it in community repository. As a result I’m dropping the package in AUR. All of you that were using my package should upgrade to the latest version from the official Archlinux repository.

A great news is coming for Enlightenment users, too: a new ConnMan module, written from scratch, that works properly with recent versions. This is reaching e-svn very soon. Stay tunned. Thanks to …

BlueZ to move to standard D-Bus interfaces

Lucas De Marchi — Thu, 19 Jul 2012 18:28:00 -0700

During the last week I was in Recife, Brazil, together with Henrique Dante, Ulisses Furquim and other fellows attending the BlueZ meeting. We discussed several topics, among them the upcoming BlueZ 5 API. That discussion started by Johan and Marcel saying BlueZ would not move to DBus.Properties and DBus.ObjectManager anymore for the next version. Main reason being that BlueZ now will have more frequent releases than it had in past and therefore there wasn’t enough time to convert the API. However I and Luiz von Dentz already had an almost working solution: I implemented DBus.Properties and …

ELC 2012

Lucas De Marchi — Tue, 20 Mar 2012 19:30:00 -0700

Hey, this is my feedback of ELC 2012. If you didn’t read the first part, about ABS 2012, you can read the previous post first.

ELC is one of my favorite conferences as I can meet several talented people and have good talks about Linux in embedded devices. This time was not an exception and I enjoyed very much. The main reason I was there was because I was going to present kmod, the new tool to manage kernel modules. But that would be only on the last day of the conference. Let’s start from the beginning.

To …

Android Builders Summit 2012

Lucas De Marchi — Sat, 17 Mar 2012 14:25:00 -0700

Four weeks ago, from Februart 13rd to Februrary 17th I was at Android Builders Summit and Embedded Linux Conference in San Francisco. I was a bit busy these last weeks so I didn’t have an opportunity to write here about the conferences as I usually do. I was going to do a post about both the conferences, but after writing a little bit I realized it would be very big. So I split in 2 and here is the one for ABS 2012; the other is coming soon.

This was my first time at Android Builders Summit. Since in …

ANNOUNCE: codespell 1.4

Lucas De Marchi — Sat, 03 Mar 2012 02:06:00 -0800

codespell 1.4 is out! Nothing really new, just a maintenance release: 1 bug fix and some new entries to the dictionary. See the entire announcement on its mailing list.

As per patches I’m receiving it seems that codespell is being successfully used by opensource projects. I’m glad codespell can help those projects, particularly people who don’t have English as their mother tongue as I don’t. It’s also an opportunity to people starting on a project, as I said in last LinuxCon Brazil.

I’m not submitting patches anymore to Linux kernel myself using codespell …

ANNOUNCE: kmod 3

Lucas De Marchi — Fri, 06 Jan 2012 06:50:00 -0800

Hey, kmod 3 is out. Really nice to finish this release. I was hoping to have it between the holidays, but there were some major bugs pending. It’s nice to see udev from git already using it instead of calling modprobe for each module. Kay reported a hundred less forks on bootup after start using libkmod and libblkid.

It’s nice too receive feedback about other architectures that we don’t have access, too. With kmod 3, sh4 joined the other architectures that were tested with kmod.

Since I’m already doing the announcements to the mailing lists, I …

ANNOUNCE: kmod 2

Lucas De Marchi — Wed, 21 Dec 2011 04:40:00 -0800

I’m glad to announce the second version of kmod. I’m sorry for not sending the first version to the mailing lists. Now I’m both writing it here and sending to the mailing list.

I thank very much the feedback received for the first version and that now Jon Masters, the maintainer of module-init-tools, is helping us with kmod and already announced that kmod will replace module-init-tools in future.

I’d like to especially thank Tom Gundersen, Dave Reisner, Marco d’Itri, Jon Masters, Luis Strano, Jan Engelhardt and Kay Sievers who have been extensively testing kmod and …

Given enough eyeballs, all bugs are shallow

Lucas De Marchi — Fri, 16 Dec 2011 08:59:00 -0800

So, in last post I said kmod 2 could be released sooner than expected if there were major bugs. Not as much as a surprise, there was 1: depending on the alias passed to the lookup function we were blocked iterating a list.

It’s now fixed in git tree. Thanks to Ulisses Furquim for fixing it and Dave Reisner for the bug report. We already have some other great stuff implemented so we’ll soon have another release.

Another great news is that now we have the maintainer of module-init-tools (Jon Masters) cooperating with us. We will discuss how …

ANNOUNCE: kmod 1

Lucas De Marchi — Thu, 15 Dec 2011 04:05:00 -0800

For some weeks now I and Gustavo Barbieri at ProFUSION have been working on a new library and a set of tools, libkmod and kmod respectively. This is the announcement of its first public release.

Overview

The goal of the new library libkmod is to offer to other programs the needed flexibility and fine grained control over insertion, removal, configuration and listing of kernel modules. Using the library, with simple pieces of code it’s possible to interact with kernel modules and then there’s no need to rely on other tools for that. This is a thing lacking on …

Having fun in the sky

Lucas De Marchi — Mon, 12 Dec 2011 21:56:00 -0800

No words to describe free fall. If you never did, you should be rethinking your next vacations ;-)

Becoming social…

Lucas De Marchi — Fri, 02 Dec 2011 15:12:00 -0800

I’ve just installed a plugin in my blog to display the common social sites below each post. From now on, if you like a post you can share it with the world using your preferred social media.

I’m using the Socialize plugin in WordPress. I’m not sure if it’s the best one: I just installed and checked it works. Any advices?

AndroidConf 2011

Lucas De Marchi — Sat, 26 Nov 2011 21:17:00 -0800

Hoje dei uma palestra na AndroidConf sobre “Modificando a API do Android”. Referências ao projeto que falei sobre AVRCP podem ser encontradas em um post meu anterior. Estou disponibilizando abaixo os slides.

EDIÇÃO 02/12/2011: coloquei uma nota no slide 7, relatando o que falei durante a apresentação sobre uso de IDE.

Para aqueles que não conseguem visualizar acima, segue o link direto para a apresentação.

LinuxCon Brazil

Lucas De Marchi — Sat, 19 Nov 2011 21:54:00 -0800

I’m back from LinuxCon Brazil, that was held in Sao Paulo on 17 and 18 November. Before the first keynote, ProFUSION was announced as becoming member of Linux Foundation :-)! Our logo is already in their members page.

It was also a great time to talk again to some developers I met in LinuxCon Europe last month and some that were not present there. One talk I really like was given by Eugeni Dodonov about the Intel Linux Graphics stack. It was a good overview of all the graphics stack in Linux, paying attention to Intel’s boards and drivers …

Back from Kernel Summit, LinuxCon Europe and ELCE

Lucas De Marchi — Fri, 04 Nov 2011 00:20:00 -0700

Last week from 23-Oct to 28-Oct I was at 3 conferences in Prague, Czech Republic, together with Gustavo Barbieri, Gustavo Padovan and Ulisses Furquim: the ProFUSION crew in Prague.

Starting from Kernel Summit, I had the opportunity to join the Bluetooth Summit and participate in the discussions regarding this subsystem in Linux, both in kernel and user space. We had a lot of hot topics to discuss, including the upcoming BlueZ 5.0, Bluetooth 3.0 (high speed), Bluetooth 4.0 (low energy) and I could also demonstrate the work I’ve been doing with the AVRCP profile. I’m …

AVRCP 1.3 on BlueZ

Lucas De Marchi — Tue, 11 Oct 2011 21:42:00 -0700

During the past weeks I’ve been working again on the BlueZ project and now we can finally announce that the AVRCP 1.3 profile is officially supported.

Technical background

For those who don’t know what I’m talking about, here comes a little background for those buzzwords:

BlueZ is the user-space part of the Bluetooth® technology stack used on Linux and Android. It has support for several Bluetooth profiles such as RFCOMM, HID, PAN, PBAP, OBEX, HFP, A2DP (some of them are implemented as separate projects) that are defined by the Bluetooh SIG. In simpler terms, BlueZ is …

ANNOUNCE: codespell 1.2

Lucas De Marchi — Fri, 30 Sep 2011 17:24:00 -0700

Since I created a mailing list for codespell, the announcements here will not have as many details as before. Checkout the new version of codespell: http://groups.google.com/group/codespell/browse_thread/thread/bce1a6f83d4bbd85

One of the issues I with codespell was that it was trying to parse cscope.out, since it’s a text file. On Linux Kernel this file can get very big and besides taking much longer, sometimes it was running out of memory :-). Now codespell has an option to ignore files, even text ones. It’s as easy as passing —skip=”*.eps,cscope.out” (notice this …

Attending AI classes

Lucas De Marchi — Wed, 21 Sep 2011 05:30:00 -0700

For those who didn’t know, Stanford is offering some online courses, starting from next month. During my graduation I already have some AI classes but I thought it would be interesting to participate in this class with thousand of students.

One area that I like on AI is the on to teach computers how to play games. I like that so much that during my AI classes in Politecnico di Milano I developed a computer game to play tic-tac-toe in NxNxN dimensions. It’s actually fun to play, and you can find some screenshots (and the code) on a …

Seminário de Linux Embarcado 2011

Lucas De Marchi — Wed, 10 Aug 2011 20:30:00 -0700

No último final de semana participei do Seminário de Linux Embarcado, em que palestrei sobre “systemd: repensando a inicialização”. O feedback que tive do pessoal foi positivo, mostrando bastante interesse nos diversos tipos de inicialização sob demanda, exclusivos desse sistema de init. Os slides estão disponíveis aqui no blog.

Gostei bastante do evento, que teve também participação do Antognolli, que trabalha comigo, sobre interfaces gráficas em sistemas embarcados usando o conjunto de bibliotecas EFL. Outro conhecido meu de outras conferências, Glauber Costa, falou sobre QEMU.

codespell 1.1

Lucas De Marchi — Sat, 18 Jun 2011 20:32:00 -0700

codespell 1.1 is just released.

Since I was receiving emails about bugs and suggestions I decided to create a mailing list. Check out the announcement of v1.1 there.

Benchmarking Javascript engines for EFL

Lucas De Marchi — Tue, 14 Jun 2011 19:25:00 -0700

The Enlightenment Foundation Libraries has several bindings for other languages in order to ease the creation of end-user applications, speeding up its development. Among them, there’s a binding for Javascript using the Spidermonkey engine. The questions are: is it fast enough? Does it slowdown your application? Is Spidermonkey the best JS engine to be used?

To answer these questions Gustavo Barbiericreated some C, JS and Python benchmarks to compare the performance of EFL using each of these languages. The JS benchmarks were using Spidermonkey as the engine since elixir was already done for EFL. I then created new …

ESC Brazil - Realtime Linux with RT_PREEMPT

Lucas De Marchi — Fri, 03 Jun 2011 20:34:00 -0700

Two weeks ago I’d give a talk about realtime Linux at ESC Brazil: “Usando Linux como Sistema de Tempo Real” (Using Linux as a realtime OS). Sadly some days before while playing soccer I broke my fibula and I had to have a surgery. I regret I couldn’t attend this conference.

At least in the company I work for there are more people with knowledge in this area. Gustavo Barbieri went there in my place and had a good feedback from the attendees.

Now I have stay home. At least for 1 or 2 months :-(.

codespell 1.1-rc1

Lucas De Marchi — Thu, 02 Jun 2011 16:30:00 -0700

I’m glad to announce the first RC of codespell 1.1. I decided to let the biggest feature for the next version and release 1.1 with the small but important features that were already implemented. This new version comes with the following features:

Verbosity level: tired of seeing so many things printed while the fixes are taking place? Now you can filter what you see
Exclusion list: there are cases in which the codespell spots a false positive, but disabling the entry in the dictionary will prevent it from fixing many other places. This is particularly true when …

Por uma web melhor e mais segura

Lucas De Marchi — Sat, 28 May 2011 01:37:00 -0700

Hoje adicionei no site um script para alertar usuários que usam versões antigas (e inseguras) de browsers. O projeto é o “Salve a Web, por favor”. Ele é opensource e pode ser visto no repositório do github. Basta carregar o script com a seguinte entrada na sua página:

<script type="text/javascript" src="http://sawpf.com/1.0.js"></script>

Acho que pela própria natureza dos posts no meu blog, a divisão dos browsers não é parecida com aquela global, em que o Internet Explorer ainda é o browser mais usado. Porém acho importante alerr os usuários. Quem sabe poderemos …

Cross-compiling with icecc/icecream

Lucas De Marchi — Fri, 13 May 2011 16:28:00 -0700

Very common questions I hear when dealing with compiling open source projects are:

How do I cross-compile a project using icecc/icecream?
How to use a different compiler version for compiling my project and still benefiting from icecc/icecream?

Note: from now on I’ll always refer to icecream instead icecc/iceccd/distcc for the name of the project.

Given you already created your cross toolchain (or downloaded from somewhere else, e.g. CodeSourcery/Linaro) these two questions are essentially the same. All you have to do is to follow the two steps below:

1. Create the “compiler environment”

Understanding …

codespell 1.0.1

Lucas De Marchi — Sat, 16 Apr 2011 16:34:00 -0700

I released codespell 1.0.1 after a small fix that is really necessary for codespell working right. Thanks to Luis Felipe Strano that spot the bug and generated another giant patch to LLVM.

Grab the latest version below:

http://packages.profusion.mobi/codespell/

ANNOUNCE: codespell 1.0

Lucas De Marchi — Fri, 01 Apr 2011 15:43:00 -0700

I’m glad to announce codespell 1.0! After 3 RCs and patches submitted to several projects, I thought it was stable enough to call it 1.0. You can download the 1.0 version below:

http://packages.profusion.mobi/codespell/codespell-1.0.tar.bz2

Seemy previous post if you are willing to know what codespell is or read the README file inside the package.

I have already filled a TODO file with ideas for the next version. They came to mind after I’ve generated a giant patch for the Linux kernel. It is the biggest patch I …

On typos and misspellings

Lucas De Marchi — Mon, 07 Feb 2011 03:56:00 -0800

This week I’m in a release mood, so I’m releasing several projects I’m involved with. If you lost the first two, checkout dietsplash 0.3 and genslide 0.3 (though the announcement was in Portuguese).

After developing for several projects I’ve noticed most of them contain typos and misspellings. Even if this does not directly affect the source quality (unless the misspellings are in documentation), if we left the comment there, we’ve left it for a reason: because we want the reader of that code to stop and read it. It’s particularly good to …

git repository is down

Lucas De Marchi — Tue, 01 Feb 2011 20:13:00 -0800

I’m turning down my repository at politreco.com. All my projects are now available either on ProFUSION’s repo or on github.

ANÚNCIO: genslide 0.3

Lucas De Marchi — Tue, 01 Feb 2011 03:14:00 -0800

É com satisfação que anuncio a primeira versão do programa genslide, genslide 0.3. É um simples programa que criei para facilitar a conversão de letras de música em slides, salvando-os em pdf através de Latex/Xelatex. Esses slides podem ser usados durante shows e cultos e venho usando-os já faz 6 meses na igreja que eu frequento. Embora ainda tenha bastante coisa para ser feita, ele já se mostra bastante útil e facilita bastante na hora de criar novos slides.

A ideia é que o usuário não se preocupe com muito com a formatação, apenas com a divisão de …

ANNOUNCE: dietsplash 0.3

Lucas De Marchi — Thu, 27 Jan 2011 14:37:00 -0800

I’m pleased to release a new version of dietsplash. This is the first announcement for dietsplash, though it has always been open source software. Here it is, dietsplash 0.3.

dietsplash is a small boot splash screen for Linux. Its aim is to do the minimal work possible so you can see your system booting without getting bored about the messages going on (or better, your client doesn’t complain to you that it’s ugly to see all those messages). Its main target is embedded systems, where running a full/big splash like plymouth is an overkill. Special …

ProFUSION work on oFono and ConnMan

Lucas De Marchi — Tue, 18 Jan 2011 12:33:00 -0800

As some of you know, I’m working on some open source projects at ProFUSION. Among them there are two projects started by Intel that are now part of Meego. If you look at Meego Architecture you’ll see these components are a great part of the Communications domain.

In ConnMan ProFUSION made mainly some bug fixes and minor improvements while we were creating a binding for e_dbus and a module for E17. It’s working pretty well, it’s fast and reliable. Examining my logs in my desktop system I can see that in less than a second ConnMan …

Open source hardware - Arduino

Lucas De Marchi — Tue, 18 Jan 2011 04:34:00 -0800

This post is just forward of an amazing documentary I saw today. It’s Arduino The Documentary. How open source hardware became cheap and fun. It’s worth watching all its 27min.

I think universities in Brazil should learn about and join projects like this.

EFL 1.0 Beta 2

Lucas De Marchi — Fri, 12 Nov 2010 19:52:00 -0800

EFL team is proud to announce beta2 of the coming EFL 1.0. WebKit-EFL also received a new snapshot as well as several other related projects. For more information, take a look at the announcement.

Criando imagens customizadas de endereços de email

Lucas De Marchi — Tue, 02 Nov 2010 07:15:00 -0700

Endereços de email são muitas vezes mascarados na web para que não sejam facilmente obtidos por programas que tem por objetivo enviar spam. É relativamente fácil escrever um programinha que fica vasculhando a web em busca de endereços de email, cadastrá-los em um banco de dados e depois utilizá-los como quisermos. Para que isso não ocorra, várias vezes nos deparamos com endereços de email passados como “joao AT gmail DOT com” ou alguma coisa do tipo. Outra técnica muito utilizada é transformá-lo em uma imagem. Dessa forma o programinha malicioso que a princípio era fácil se torna bem mais difícil …

Easily embedding WebKit into your EFL application

Lucas De Marchi — Sat, 23 Oct 2010 23:53:00 -0700

This is the first of a series of posts that I’m planning to do using basic examples in EFL, the Enlightenment Foundation Libraries. You may have heard that EFL is reaching its 1.0 release. Instead of starting from the very beginning with the basic functions of these libraries, I decided to go the opposite way, showing the fun stuff that is possible to do. Since I’m also an WebKit developer, let’s put the best of both softwares together and have a basic window rendering a webpage.

Before starting off, just some remarks:

I’m using here …

Understanding RT by graphics

Lucas De Marchi — Sun, 29 Aug 2010 03:30:00 -0700

A lot of people seem not to understand very well what real-time means. They usually tend to think RT has anything to do with performance and the raw throughput. It doesn’t. It’s all about determinism and guarantees.

This post’s title has “by graphics” words. I think the graphics below are worth a thousand words. I obtained them while porting the RT tree to Freescale boards some weeks ago at ProFUSION. Basically I’m running a task that wakes up every 40ms, run a tiny job, send some numbers through the network and sleeps again. The time in …

WebKit

Lucas De Marchi — Sat, 28 Aug 2010 05:15:00 -0700

After some time working with the EFL port of WebKit, I’ve been nominated as an official webkit developer. Now I have super powers in the official repository :-), but I swear I intend to use it with caution and responsibility. I’ll not forget Uncle Ben’s advice: ”with great power comes great responsibility”.

I’m preparing a post to talk about WebKit, EFL, eve (a new web browser based on WebKit + EFL) and how to easily embed a browser in your application. Stay tuned.

strace, valgrind and gdb as a strace-like tool

Lucas De Marchi — Fri, 30 Jul 2010 06:18:00 -0700

A long time since I do not post some technical thing. Time to share something I learnt during latest months.

My boss at ProFUSION always says there are only 2 debugging tools worth using: strace and valgrind. Indeed, they are very helpful while developing software in C. If you don’t know them, hurry! Google it. Basically what I can do is to summarize their functionality:

strace traces all system calls a program does. You don’t even need the source code. Suppose a software is misbehaving and you want to know what files it is opening: all you have …

Brasil x Holanda

Lucas De Marchi — Fri, 02 Jul 2010 23:37:00 -0700

Brasil perdeu. Infelizmente estamos fora da copa.

O Juca Kfouri resumiu praticamente tudo o que eu acho desse jogo. Só pra complementar: o time de laranja era uma equipe de teatro ou de bonecas?

Now, officially an EFL developer

Lucas De Marchi — Wed, 05 May 2010 02:36:00 -0700

Last week I was officially added to EFL developers list. After contributing some patches to eina, edbus, elementary and E17 (especially to connman module), Gustavo Barbieri, who is also my boss at ProFUSION, added me to developers list giving me commit rights on EFL svn.

He said me some weeks ago that the only thing missing to add me as developer was that I’d have to use E as my window manager. Fair enough. If one wants to be a developer of a certain program, it’s better to first be an active user. So, last Friday I wiped …

Linux Collaboration Summit 2010

Lucas De Marchi — Wed, 21 Apr 2010 22:29:00 -0700

And this was the Linux Collaboration Summit 2010:

Linux Collaboration Summit 2010 from Kenny Moy on Vimeo.

I’m appearing on this video exactly at 2:00 :-D. After it shows Google giving Nexus One phones to everybody. Really nice.

Embedded Linux Conference 2010

Lucas De Marchi — Thu, 15 Apr 2010 09:17:00 -0700

So, today was the last day of the Embedded Linux Conference. Now, I’ll be here in USA for the Linux Collaboration Summit. It was really cool and it was amazing to meet people you are only used to chat, exchange some emails or that you heard about. Just to name some: Steven Rostedt, Greg Kroah-Hartman, Frank Rowand, Mike Anderson, Andrew Morton, Jon Corbet and others. I was really impressed too seeing Rostedt programming or Greg answering emails. What a great guys

And yesterday I presented my work, talking about the optimization of the Linux scheduler for soft real-time when …

Banco do Brasil + Linux 64 bits

Lucas De Marchi — Tue, 30 Mar 2010 03:06:00 -0700

Faz 1 mês mais ou menos que liguei no Banco do Brasil reclamando que a “solução de segurança” do site deles não estava funcionando no meu Linux 64 bits. Sem grandes surpresas, depois de me perguntarem se eu tinha a VM java da sun instalada, versão, etc, eles me passaram para o suporte de segundo nível. Pediram o meu telefone, dizendo que entrariam em contato (isso foi no sábado).

Logo na segunda-feira de manhã me ligaram e após mais um tempo conversando, ele disse: “o problema é que a nossa solução de segurança não é homologada para a jre 1 …

Amazing kernel related blog

Lucas De Marchi — Tue, 23 Mar 2010 03:45:00 -0700

Today while reading “posts” on Buzz and digging in my RSS reader, I found this blog: http://smackerelofopinion.blogspot.com/ made by an ubuntu engineer. How many amazing posts there are on this blog. Particularly interesting is the one about ACPI Debugging and the other about perf, the tool I posted about some days ago (although it covers just a tiny amount of things this tool is capable of).

When I have some spare time I’ll try to use that first post to debug the ACPI on my buggy asus laptop, where temperature goes sometimes as high as 90 …

Pescaria 2010

Lucas De Marchi — Sun, 21 Mar 2010 21:33:00 -0700

Final de semana pra relaxar com a família. Seguindo a sugestão de Ataíde e Alexandre, fomos pescar. Que pena que o meu peixe de 12kg acabou escapando. Algumas fotos:

[caption id=”” align=”aligncenter” width=”640” caption=”Respiração”][/caption]

[caption id=”” align=”aligncenter” width=”640” caption=”Peixão”][/caption]

[caption id=”” align=”aligncenter” width=”640” caption=”Meu pai pegando um peixe”][/caption]

Mais fotos em: http://picasaweb.google.com.br/lucas.de.marchi/Pescaria?feat=directlink

Stripping perf out from kernel source

Lucas De Marchi — Wed, 10 Mar 2010 14:19:00 -0800

You may have heard about perf, a tool made by Linux kernel developers to help debugging, benchmarking and profiling.

The problem is you have to download the whole kernel source in order to compile perf. If you are not used to follow kernel developping, most likely you will not have its source. But it’s still possible to compile perf.

As I’m helping to maintain perf package in Archlinux, I made the following script to strip perf from a given kernel version:

#!/bin/bash

function usage() {
    cat - <
This script works fine with latest 2.6.33 kernel. Regularly I …

Mais um infeliz cliente da Telefônica

Lucas De Marchi — Thu, 25 Feb 2010 05:01:00 -0800

É impressionante como a Telefônica pode ser uma operadora tão ruim. Não bastasse ser ruim e cara, você fica preso a ela por diversos motivos. Explico: tentando diminuir os gastos da linha telefônica, hoje liguei lá para contratar uma segunda linha telefônica, mas do tipo Linha Lazer. A intenção era começar a usar essa segunda linha só para o speedy e depois migrar (usando a portabilidade numérica) a outra linha para uma operadora melhor (e mais barata, muito mais barata).

A diferença de assinatura entre a Linha Clássica, que temos agora, contra a Linha Lazer: R\$ 40,35 contra R …

Coming back, with git tips

Lucas De Marchi — Wed, 10 Feb 2010 23:52:00 -0800

So, it has been some months I last wrote on my blog. Not because I don’t have things to write, but because sometimes I’m too lazy do empty my “queue of things to write about”. Nothing better than start with one thing at a time.

Since january I’m working at ProFUSION. As before when I was mainly developing for Linux kernel and finishing my thesis (@ USP / Polimi), I’m using git a lot. Even in projects in which upstream is using a centralized approach like subversion, I simply can’t live without a local tree and thus …

Parallelizing

Lucas De Marchi — Wed, 09 Dec 2009 19:00:00 -0800

Sometimes we discover that we don’t have to parallelize only the software. We must also parallelize the way it is written.

Thus, one of the last days of my graduation in Computer Engineering:

[caption id=”attachment_220” align=”aligncenter” width=”560” caption=”One day of hard work”][/caption]

Almost finished!

Welcome Windows 7

Lucas De Marchi — Sat, 24 Oct 2009 04:36:00 -0700

Welcome from a Linux user…

Python, bpython and my university’s email

Lucas De Marchi — Wed, 21 Oct 2009 02:15:00 -0700

Almost a year ago I posted in my past blog (in portuguese, automated translation) a tutorial on how to use greasemonkey to workaround the ugly interface of my university’s webmail. More specifically, in Firefox it looses the ability to select all emails. I took that just for an example… the real goal was to delete all emails since I access them through Gmail and periodically I get the email: “your mailbox is full…”. So, how could I delete them without having to download them all? Simple: connect through POP3 and issue the “dele” command. I could do that even …

Trissa - update status

Lucas De Marchi — Wed, 14 Oct 2009 16:26:00 -0700

Just to let you all know some updates to Trissa: currently it’s in a hold state, waiting for next stable Ogre release, which is version 1.7. So until they release this version I’ll hold Trissa in a beta status, although it’s working great right now and all fixes for 1.0 are in place.

The biggest problem with current version of Ogre is that it doesn’t have proper support for multi-threaded games, or better, only one thread is able to make calls to Ogre functions which change the rendering states. In the design of Trissa …

TinyOS

Lucas De Marchi — Wed, 07 Oct 2009 01:32:00 -0700

As I did with previous projects I had at my university, I’d like to share another one: it’s a project using TinyOS. It’s mainly intended for education purposes, so if you are trying to learn TinyOS, it’s a good example to look at.

What does it do?

It’s a platform to monitor temperature and humidity of various rooms in a house. All sensors must collect data every X seconds and send them to sink, a predefined node. Sink can also change the value X and sensors may not reach sink in a single hop, so …

Testando o google translate com o último post

Lucas De Marchi — Fri, 02 Oct 2009 13:57:00 -0700

Escrevi o último post em italiano e queria testar o Google Translate. Aqui está o link do último post traduzido para o Português.

Não digo que foi ruim para um tradutor automático. Em geral creio que dê para entender, mas algumas partes foram bem divertentes. Um exemplo é a frase “Eu e meu amigo fomos para Mateus Pomatt”, tradução de “Io e il mio amico Matteo siamo andati a Val Formazza”. Perdeu-se todo o sentido, que seria: Eu e meu amigo Matteo fomos a Val Formazza.

De qualquer forma achei legal poder manter a forma do site só traduzindo-o com …

Val Formazza!

Lucas De Marchi — Fri, 02 Oct 2009 13:44:00 -0700

E’ da un po’ di tempo che non scrivo niente sul blog, ma è perché era un po’ preso con le cose dell’università. Spero poter aggiornarlo più spesso ora.

Questo post è sulla passeggiata che ho fatto un mese fa. Io e il mio amico Matteo siamo andati a Val Formazza. E’ stato davvero spettacolare. Non posso immaginare una persona ritornare dall’Italia senza essere andato al meno una volta in montagna. È ancora più difficile da capire che tanti italiani non siano mai andati. Me lo raccomando a tutti!

Vi lascio qualche foto.

[caption id=”” align=”aligncenter” width …

Countdown restarted

Lucas De Marchi — Tue, 15 Sep 2009 12:00:00 -0700

Por motivos de força maior, a contagem regressiva foi reiniciada. Nova data: 27 de setembro.

12 dias, e contando…

Suse studio

Lucas De Marchi — Sun, 16 Aug 2009 00:49:00 -0700

I was really impressed about the demos I saw in last Novell’s announcement : Suse Studio. So last week I applied to have an account since it’s not open for everybody. Today I received the following email:

Thank you for your interest in SUSE Studio, a new service that makes
it quick and easy to create and test software appliances from your web
browser. We are pleased to invite you to try SUSE Studio.

To accept this invitation and take SUSE Studio for a spin, please
visit this link:

****************************************

Alternatively you can go to http://www.susestudio.com/account …

The final countdown

Lucas De Marchi — Sat, 15 Aug 2009 16:03:00 -0700

Em 30 dias estarei pousando no Brasil!!

A contagem final começou.

Preparem a picanha que eu estou chegando.

Compiler’s compiler version

Lucas De Marchi — Sat, 15 Aug 2009 02:06:00 -0700

Today I was just wondering… what’s the version of the compiler which compiled my compiler. Quite a strange question to make myself and I really don’t know where this curiosity came from.

Looking in Wikipedia:

Early compilers were written in assembly language. The first self-hosting compiler — capable of compiling its own source code in a high-level language — was created for Lisp by Tim Hart and Mike Levin at MIT in 1962.^[2]^ Since the 1970s it has become common practice to implement a compiler in the language it compiles, although both Pascal and C have been popular choices …

Trissa 3D is arriving

Lucas De Marchi — Wed, 29 Jul 2009 21:59:00 -0700

I’m proud to release version 0.98 of one of my projects, Trissa. Whilst this is not a version intended for the end-user, I’d like to have some more users to find bugs before releasing 1.0. Be warned: this is intended for developers only. There’s no package yet, so you have to compile it yourself. Some screenshots:

I’m putting online also a presentation I gave about this project in my university, Politecnico di Milano. Trissa is the name of the Tic-tac-toe game in italian and I made it as part of a course: Laboratory of …

Awesome!

Lucas De Marchi — Mon, 13 Jul 2009 17:34:00 -0700

Just a short post to share a beautiful Brazilian song. Two days ago my friend was playing it, now it just doesn’t get out of my head :-)

Have fun.

Sharing some homeworks

Lucas De Marchi — Sat, 11 Jul 2009 23:01:00 -0700

So, I’ve spent some time last weeks doing some homeworks for courses at Politecnico di Milano. One of them is for the course “Image analysis and synthesis” in which I did together with a friend of mine some animations in Blender.

The goal was to make some animations of sport scenes and after apply a kind of “filter” in Matlab to simulate a high exposure of the camera, or, if you prefer, to draw the trace of the ball. As the only object moving in scene was the ball, these two are roughly the same thing. This is done …

The browser war continues…

Lucas De Marchi — Sat, 04 Jul 2009 11:55:00 -0700

One month ago I wrote a post talking about the new Chrome for linux, or better yet, that the Chromium (this one is opensource) is finally working well under Linux, and so fast.

Well, while the Chromium guys are working hard to get a decent browser, the firefox guys didn’t stop working and last week Mozilla released the so waited Firefox 3.5.

My 2 biggest complaints about the prior version were that (i) the awesome bar gets slow as time pass and you visit a lot of sites and (ii) the start up time. The first one I …

Benvinda de volta Oficina G3

Lucas De Marchi — Sun, 28 Jun 2009 14:35:00 -0700

Creio que nem todos conheçam a banda Oficina G3. Em poucas palavras, é uma banda evangélica de rock muito boa.

O rock pesado nunca foi meu estilo favorito. Passei a ouvir Oficina principalmente quando lá pelo ano 2000 (acho) eles partiram para um estilo mais light com CDs como “Acústico” e “Ao Vivo no Olímpia”. O último CD deles que ouvi bastante foi o “Humanos” quando eles voltaram para o rock que apesar de pesado, era ainda “ouvível”.

Com a saída do vocalista PG do grupo eles deram uma “recaída” e depois de algum tempo sem lançar nenhum CD lançaram …

Meu Brasil brasileiro

Lucas De Marchi — Mon, 22 Jun 2009 01:00:00 -0700

Questo post è dedicato ai miei amici italiani. Mi dispiace, ma l’Italia ha giocato troppo male e il Brasile… beh, è il Brasile!!

Sentite la differenza tra il cronista brasiliano e l’italiano.

Italiano:

Brasiliano:

Ci vediamo domani. Io sarò con la maglietta della nazionale brasiliana ;-)

Chromium

Lucas De Marchi — Fri, 05 Jun 2009 22:57:00 -0700

After reading this post at “Linux Today” I decided to install the so expected Linux version of Chrome, the Google’s browser.

As I use Arch Linux, I haven’t expected to have a compiled version linked directly by the chromium’s website. Instead, I was hoping Arch’s developers already packaged it. And, with no big surprises, they did. Just to clarify a thing before continuing: Chromium is the open source projected behind Chrome (which is not opensource).

I’m not writing this post to repeat what’s already written there. So read it too. As opposed to his …

Saudade…

Lucas De Marchi — Thu, 28 May 2009 21:04:00 -0700

No final do ano passado meu amigo Fadinha Ricardo publicou um post em seu blog falando sobre saudade. Concordo com o sua afirmação. Como escrevi nos comentários daquele post, em 2004 foi feita uma sondagem a tradutores profissionais por uma empresa britânica e a palavra “saudade” do português foi eleita como uma das mais difíceis de se traduzir.

O bom porém da saudade é quando você mata ela. Que sensação boa!!

Resolvi tocar nesse assunto porque meu irmão veio me visitar. Nos últimos dois finais de semana pude estar com ele e dar uma passeada pela Itália. Tantos lugares, tantas …

Playing with your cache

Lucas De Marchi — Wed, 20 May 2009 21:00:00 -0700

Another possible titles could be “how to really slow down your computer” or “why caches are so important in computer architectures”. I started playing with turning my cache on and off last week using Linux because there are some situations in which you have to know why a piece of software is not working as expected. A possible problem could be the well known cache trashing, in which the contents of the cache is thrown away very often. Turning it down may give an answer if this is really the problem since now even running very slowly this variable is …

Hello world - Again!

Lucas De Marchi — Wed, 06 May 2009 17:06:00 -0700

I’m back again!!

Soon I’ll post some news and explain why I’m changing home.

Update your RSSs as I’ll not update my past blog anymore. So, as the title says:

HELLO WORLD!!

Driver radio STLC2590

Lucas De Marchi — Fri, 03 Oct 2008 15:52:00 -0700

This is a re-post of a project I did. It’s still the same, no version upgrade. I’m putting it on this blog as I don’t update or track comments on the old one and people generally go there through google.

—

First of all I’d like to thank ST Microeletronics for give us the opportunity to work on a Linux driver for their chip STLC2590. All the documentation needed to write it was given by them. Thanks also to Patrick Bellasi, our tutor, which has tough us so much in regard to Linux driver development, APIs of …