handyfloss

I have recently come across a problem while creating a LaTeX style (for making A0-size posters). Maybe it could be avoided or solved more elegantly, but I wanted to solve it with conditionals.

Basically, what I wanted to do was define a command (actually, an environment) that accepted one argument, and make it return different output, depending on the argument:

if (argument equals something) then
  do something
else
  do somethingelse
end if

It gave me some headaches to get it, but I also learned some interesting things on the way. There are at least two ways of playing with conditionals: defining boolean variables or directly using logical comparisons.

Defining logical valiables

We can define a logical variable logvar as follows:

\newif\iflogvar

By default, it is set to false. We can set it to true by:

\logvartrue

and back to false by:

\logvarfalse

The variable can be used in a conditional as follows:

\iflogvar
  aaaa
\else
  bbbb
\fi

You can think of the above code as a single object, the output value of which will be “aaaa” if logvar is true, and “bbbb” if false. Basically, the following code will, thus, output “Today is great“:

Today

\newif\ifismonday

\ismondayfalse

\ifismonday
  sucks!
\else
  is \textbf{great}
\fi

Direct logic comparison

The example I provide works for numbers, but check this page for more info. Recall that LaTeX works with integers (counters) and text strings. As far as I know, floating point operations are impossible in LaTeX (nothing is actually impossible in LaTeX, just veeery difficult).

For example, defining the following command in the preamble:

\newcommand{\isitthree}[1]
{
  \ifnum#1=3
    number #1 is 3
  \else
    number #1 is not 3
  \fi
}

allows us to call it in the document, so the following outputs “We know that number 33 is not 3”:

We know that \isitthree{33}

Nesting

Obviously the conditionals can be nested (put one inside another), when more than one condition needs to be tested. For example:

Today

\newif\ifismonday
\newif\ifistuesday

\ismondayfalse
\istuesdaytrue

\ifismonday
  sucks!
\else
  \ifistuesday
    almost sucks.
  \else
    is \textbf{great}
  \fi
\fi

It is not new: we all know that companies like Microsoft, Google and Yahoo! sold their souls to the capital so badly, that they’d even collaborate with communism. Paradoxical, uh? In other words: they love freedom, but they love money best (I don’t berate China for being communist, but for its lack of liberties). These companies will collaborate with any totalitarian government or do any unethical thing if it returns money… and this is legal? Surely not.

The last bit is Yahoo! betraying the confidence in their online privacy of some Chinese anti-government activists, and selling their identities to the police of that country. You can read more at the BBC site.

Yahoo! kind of defends itself by saying that it has to comply with the local laws in the countries it operates. I call this bullshit. If the laws of some country are not ethically acceptable, or are legally incompatible with the civil rights of most “first world” countries (including the original country of the company, in this case the USA), then the company must dismiss operating on the country at all, unless it accepts abiding by these laws (as Yahoo! itself says), therefore supporting them, and therefore being liable to a punishment for their application (e.g. they can be fined in the USA for doing whatever in China, if this act is legal in China, but illegal in the USA). If they don’t have what it takes to face the punishment, they should refrain from operating in the country at all.

More news:

1) Digg search for Yahoo and China

2) Same, for Google (incidentally, see the mentions to Wikipedia not bowing to China).

3) Same, for Microsoft. Check, e.g., Gates defending Google over censorship issue.

4) Yahoo!, Microsoft ink web pact with Chinese government

Yesterday a new failure from Iberdrola turned the power supply of the whole campus off several times. So, here goes the updated list of blackouts I have been able to compile, with comments if any:

1. 2007-Aug-27 (at least three short power failures, 5-10 minutes apart)
2. 2007-May-19
3. 2006-Oct-21 (they warned beforehand)
4. 2006-Sep-14 (Orpheus fell, the DNSs fell, the DHCP servers fell)
5. 2006-Jul-04 (Orpheus didn’t fall)
6. 2006-Jun-16
7. 2006-Jun-13
8. 2006-Jun-08
9. 2006-Jun-04
10. 2006-May-26 (The card-based automated access to the Faculty broke down)
11. 2005-Dec-21
12. 2005-Dec-13

Summary: 12 blackouts in 621 days, or 51.8 dpb (days per blackout). 100 days since last blackout. Average dpb went up by 4.2.

First post in the series: here

I just read, by chance, a very interesting essay a Wikipedia administrator wrote in his personal page. It deals with people spamming or vandalizing Wikipedia, for fun or for personal promotion/economical benefit.

I’ll quote the intro paragraph:

Let’s face facts: Wikipedia has become an important force on the Internet. If you’ve got a business to run or a belief to circulate there’s a big temptation to hit that edit button and do your thing. You’re on your honor here. Most people have honor, which is why Wikipedia is huge and (usually) pretty darn good, but then there’s that thought – what if you could harness this site and make it work for you?

You aren’t the first person to get that idea. And hello there, I’m a Wikipedia administrator.

Read more in the whole essay.

I recently wrote (actually, my last post, 12 days ago), a howto of sorts with my experience installing Compiz Fusion on my laptop. Yesterday I came back from my vacations, and repeated the feat with my destop computer at home.

The setup is quite different:

CPU: AMD Athlon 2800+
Graphics: nVidia FX 5700 (256MB)

And the effort is also quite different: it took me much less! Partially, this was because of my previous exprerience, but mainly the reason is that the graphics card here is nVidia. Yes, let the world know that ATI cards suck on Linux.

The problem is that ATI cards need XGL to have Compiz running, but nVidia cards make use of AIGLX natively, so the installation has only two steps: (1) installing the nVidia driver, and (2) installing the Compiz Fusion packages.

Installing the latest nVidia driver

As with the ATI card in my laptop, I decided to use the proprietary drivers from the nVidia site. The choice-making interface is so similar, actually, to that of ATI. I had to go Graphics Driver->GeForce FX series->Linux x86->Go!, and download this installer.

BIG WARNING: before actually installing anything, remove a previous installation of the nVidia drivers, if you installed them “the Debian way”. For that, do:

% aptitude purge nvidia-glx

I have a friend who did not do so and… Ok, ok, it happened to me. If you do not do the above, everything seems to work fine, but everytime you reboot the X server will crash, and you might get incredibly annoyed by that.

To perform the installation, simply run, as root:

% sh path-to-file/NVIDIA-Linux-x86-100.14.11-pkg1.run

Then, just modify your xorg.conf file to contain the following:

Section "ServerLayout"
  Identifier     "Default Layout"
  Screen       "Default Screen" 0 0
  InputDevice    "Generic Keyboard"
  InputDevice    "Configured Mouse"
  Option         "AIGLX" "true"
EndSection

...

Section "Extensions"
  Option         "RENDER" "true"
  Option         "Composite" "Enable"
  Option         "DAMAGE" "true"
EndSection

Installing Compiz Fusion packages

The procedure is exactly the same covered in my previous post. In short:

1) Add the Shame repository to your /etc/apt/sources.list:

deb http://download.tuxfamily.org/shames/debian-sid/desktopfx/unstable/ ./

2) Get the signature for the repo:

% gpg --keyserver pgpkeys.mit.edu --recv-key 11F6E468
% gpg -a --export 11F6E468

3) Update and install:

% aptitude update
% aptitude install compiz-fusion-all --a

Any time you want to run Compiz, just execute:

% compiz --replace -c emerald

Shorter than the ATI thing, uh?

I have a previous post with what I’ve done to my laptop, and in that post it’s not mentioned, but I managed (quite a while ago) to make Beryl work under Ubuntu Dapper Drake. Dapper is getting older, but I am not having good experiences installing Edgy and Feisty on the laptop. I have managed to install Debian Etch with no problem, but the wireless driver was not working properly (for me, a showstopper) until Lenny.

So now I have a Debian Lenny partition, plus three other: the original WinXP, the Ubuntu Dapper I am still using as “main” OS, and a Fedora 7 I installed just because it came in a DVD with a magazine I bought for a train trip I had not brought any reading material with me :^)

Since I am on vacation, and I have plenty of time (although I don’t want to spend all of it on my comp), I decided to give Compiz Fusion a try, mostly after seeing what it its capable of.

First things first, the specs of my laptop are:

Fujitsu-Siemes Amilo PI1536
CPU: Intel Core 2 Duo T7200 2×2.0GHz
RAM: 2x1Gb
HD: 120Gb SATA
Display: 15.4 WXGA
Graphics: ATI Mobility Radeon X1400 (128Mb dedicated/512Mb shared)

The only relevant parts above are that it has an ATI graphics card (which, under Linux, sucks), and that it has Core 2 CPUs, which are amd64-capable (which is both great, for performance, and sucks, for drivers and software compatibilities). So, my second step was:

Installation of ATI drivers

If you want to take the best out of your ATI card, you have to tell your X.org graphics server to use the fglrx driver, and not the default vesa one. You can install this driver from the official Debian repositories, but for me those packages (fglrx-driver and related ones) didn’t do it.

So, I googled a bit, and followed the most widespread recommendation: to install the latest non-free (sigh) driver from the ATI site. For that, I chose the options: Linux x86_64 -> Mobility Radeon -> Mobility Radeon X1400 -> Go, reaching this page, and downloading this 38MB binary (for the record, the 32bit version of the drivers is exactly the same .run file).

Next, I followed the remaining information in this excelent thread in linuxquestions.org. Namely, I downloaded the needed packages (the code is copy-paste-able):

% aptitude install module-assistant build-essential dh-make debhelper debconf libstdc++5 linux-headers-$(uname -r) ia32-libs

Beware that the ia32-libs packages is not mentioned in the linuxquestions.org thread (assuming that you already have it installed), but it is required.

Next, run the ATI binary inside a dedicated directory (I did it as root, but it is not compulsory):

% mkdir /root/fglrx
% cd /root/fglrx
% mv wherever-I-downloaded-it/ati-driver-installer-8.32.5-x86.x86_64.run .
% chmod +x ati-driver-installer-8.32.5-x86.x86_64.run
% ./ati-driver-installer-8.32.5-x86.x86_64.run --buildpkg Debian/lenny
% rm or mv the .run file wherever you want

This generates a bunch of .debs in the /root/fglrx dir. Next, install them, and compile the driver (for this, you do need to be root):

% dpkg -i fglrx-*.deb
% cd /usr/src
% m-a prepare
% m-a a-i fglrx

The linuxquestion.org thread mentions modifying the /etc/X11/xorg.conf file in two ways. First, disable compositing, adding:

Section "Extensions"
Option "Composite" "Disable"
EndSection

to it, and then running:

% aticonfig --initial
% aticonfig --overlay-type=Xv

For me, both were superfluous, because I made a copy of my Ubuntu xorg.conf, and them made minimal changes (if at all). However, the first change (disabling compositing) was straightforward wrong. If I want to use Compiz Fusion, I need to have it. Relevant excerpts from my xorg.conf:

Section "Module"
  Load  "i2c"
  Load  "bitmap"
  Load  "ddc"
  Load  "dri"
  Load  "extmod"
  Load  "freetype"
  Load  "glx"
  Load  "int10"
  Load  "type1"
  Load  "vbe"
EndSection

...

Section "Device"
  Identifier  "aticonfig-Device[0]"
  Driver      "fglrx"
  Option      "VideoOverlay" "on"
  Option      "OpenGLOverlay" "off"
EndSection

...

Section "Screen"
  Identifier "aticonfig-Screen[0]"
  Device     "aticonfig-Device[0]"
  Monitor    "aticonfig-Monitor[0]"
  DefaultDepth     24
  SubSection "Display"
    Viewport   0 0
    Depth     24
    Modes    "1280x800" "800x600" "640x480"
  EndSubSection
EndSection

...

Section "DRI"
  Mode         0666
EndSection

Section "Extensions"
  Option "Composite" "1"
EndSection

After all this fuss, and to ensure you have it all running OK, try to insert the module as root:

% modprobe fglrx

Then, make sure it loads everytime you reboot (include it in /etc/modules if necessary, but it shouldn’t be).

Next, reload the X server, and check that now it is running the fglrx driver, by doing the following (as user is fine):

% fglrxinfo

It should display something like the following:

display: :0.0 screen: 0
OpenGL vendor string: ATI Technologies Inc.
OpenGL renderer string: ATI Mobility Radeon X1400
OpenGL version string: 2.0.6650 (8.39.4)

If, instead, it says something about mesa3d, it didn’t work.

Now, the second step is…

Installing Xgl

With the standard X.org server we have a problem. We can load the fglrx driver, but we can not activate compositing (see last three lines of my xorg.conf file above). If we activate compositing in the xorg.conf file, the ATI driver will not be loaded (don’t ask me why, it just seems to happen). If we deactivate compositing, the ATI driver gets loaded, but without compositing, we can not use Compiz.

The solution is to install Xgl which is an X server (or, I think, a kind of layer that runs on top of the X.org server) that allows for the above trick. There seem to be two “ways” of getting proper compositing: Xgl and AIGLX. The general agreement on the net seems to be that the latter is “better”, but only the former seems to work with ATI cards (read the “AIGLX with AMD (ex-ATI) Proprietary Drivers” section in the AIGLX Wikipedia article, because it hits the problem dead-on). With Xgl I can make use of the fglrx driver and have compositing at the same time.

We are lucky here, because there are Debian repositories for Xgl. I found out about them in this howto in tuxmachines.org. Most of the info there is mostly… ehem… useless (for me), but reading it I found a repo for Xgl. I just have to add the following line to my /etc/apt/sources.list (beware that the original mention in the tuxmachines.org page says “binary-i386”, and I had to change it to “binary-amd64”):

deb http://www5.autistici.org/debian-xgl/debian/ binary-amd64/

I then had to do aptitude update, and I (of course) got an error telling me that some signatures couldn’t be verified (read my own article about secure APT and/or the wonderful Debian wiki to know more). I think the key is 11F6E468, and it corresponds to Francesco Cecconi (mantainer of the repo). It is downloadable from pgpkeys.mit.edu (follow instructions on my previous post, or the ones in the Debian wiki). If you want, do not skip reading the parent page of the repository.

After the keys are OK, it’s just a matter of doing (as root):

% aptitude update
% aptitude install xgl

Now you are done installing, but will have to actually use Xgl. This gave me some headaches, not because I didn’t know where to put things, but because I didn’t know exactly what to put. I read, and followed, the instructions in freedesktop.org, and (after all, the blog seems to be useful for someone: myself) a previous post of my own.

I am using GDM, so my final setup was the following: first generate a suitable entry in the GDM menu, by creating a file named /usr/share/xsessions/xfce4-xgl.desktop (or whatever, but in the same dir, and ending in “.desktop”), and putting the following inside:

[Desktop Entry]
Encoding=UTF-8
Name=Xfce-Xgl
Exec=/usr/local/bin/startxgl_xfce
Icon=Type=Application

The string after “Name=” is the one that will appear in the GDM menu, and the one after “Exec=” what will be executed when selecting that entry.

Next, we have to create the string we promise above (/usr/local/bin/startxgl_xfce), and put the following inside:

# Start the Xgl server:
Xgl -fullscreen :0 -ac -accel glx:pbuffer -accel xv:pbuffer -fp /usr/share/X11/fonts/misc & sleep 5 && DISPLAY=:0
# Start Xfce:
exec xfce4-session

As you can see, I am telling Xgl to load a font (with -fp) that was giving me headaches, because the server would die saying that the font was missing when I didn’t include that option. Your mileage may vary.

Now, everytime we select the entry labeled “Xfce-Xgl” in the GDM menu, we will have the Xgl server running.

Installing Compiz Fusion packages

I think the aforementioned autistici.org repo has compiz packages, as well as the default Debian Lenny repos. But net consensus seems to be that they are not the way to go. Everyone praises two repositories: Treviño’s and Shame’s. I chose the latter, adding the following line to my /etc/apt/sources.list:

deb http://download.tuxfamily.org/shames/debian-sid/desktopfx/unstable/ ./

I think I went through the same chores as above for key verification, Shame’s key being A42A6CF5.

After that, I installed the following package (it installs all of the needed packages):

% aptitude install compiz-fusion-all

After that, and inside my “Xfce-Xgl” session, I just did the following, as some googling revealed:

% compiz --replace

But… it didn’t work :^( It complained in the following manner:

Fatal: Failed test: texture_from_pixmap support
Checks indicate that it's impossible to start compiz on your system.

I found a lot of pages, threads and howtos in the net stumbling upon this same problem (for example, this one at ubuntuforums.org), but none with the answer. Really. None. The most enlightening tips where the use of the -v, -h and --help switches for compiz. The first one requests verbose output, the second one help about “short” options, and the third one help about the “long” options. With the latter I discovered the --force-fglrx switch, which saved the day! Yes, I now use the following command to start Compiz:

% compiz --replace -c emerald --force-fglrx

I have two things to say at that point. First: this Compiz Fusion is visually astonishing! It is full of great ideas, and has a lot of settings to play with. The second thing is not so nice: some glitches are present. For example, my Konsole windows get transparent background for no reason, and the refresh is horrible (when text reaches the bottom on the terminal, it starts to overwrite itself. One must hide and un-hide the window for proper refreshing, which is unacceptable). The latter also affects other windows, which, all in all, makes it unsuitable for much comfort.

However, Compiz Fusion is new, hot and experimental. I love playing with it, but right now it can not be relied upon. On the bright side, in the three days from my installation, the packages have been updated three times! I suppose some aptitude upgrade cycles will fix the issues eventually.

And that’s it, dear reader.