Atheism in the land of a thousand Gods

Having been raised in a devout Hindu household, I never had the courage or the desire to think or question my beliefs. I just performed whatever religious liturgy was expected of me, lest I end up offending one of the innumerable gods of Hinduism and be stuck forever in the cycle of life and death. Yikes! What could have transpired in the life of this hopelessly brainwashed religious retard that made him question and ultimately renounce his religion? I would love to look back on the past year of my life and pinpoint at one moment of sudden clarity and epiphany where I stepped out of the self-constricting bubble of religion and let the light of science and knowledge wash over me and transform me. The truth is, it was more of gradual change involving several events like death of a close relative, exposure to people from other religions besides my own, Aldous Huxley’s Brave New World (being forced to follow a religion from birth is not much different than decantation in the World State) and liberal amount of meditation and introspection.

To renounce something, you first have to understand it thoroughly. All religions, despite their proclaimed differences, when distilled down to their bare essence, can be broken down into three components.

  • God
  • Self
  • Rituals connecting the two

God

The coupling between god and religion is so strong, it’s impossible to think of one without dragging in the other. But do god and religion really need to be bundled together this tightly? I sincerely want to believe that there is a force more powerful and knowledgeable than an individual that primarily exists to guide him. Perhaps this force is just my own subconscious mind, perhaps it is the collective intelligence of mankind in a “By your powers combined, I am Captain Planet” sort of way. I cannot be sure and, at this point, have no desire to pursue this question any further. I am happy being an agnostic atheist. What I am sure of is that, even in gnosticism, I wouldn’t need no stinkin’ religion attached to my idea of god.

Self

If you look at Self from a religious perspective, your only purpose is to praise and worship the lord of your religion in hopes of seeking a place in heaven/enlightenment/liberation from life and death cycle. So, once you become an atheist and are no longer bound to submit to the will of the Almighty, what is your purpose? This is not an easy question and the difficulty of finding an answer is perhaps the reason why religion was invented in the first place – a clear cut answer to a difficult question that requires nothing more than your silent obedience. I subscribe to the philosophy that life is inherently meaningless. You are free to add whatever meaning you see fit.

Rituals connecting the two

If we do away with the worshipping aspect of a religion, they all preach the same message. From Monty Python’s Meaning of Life, “it’s nothing very special. Uh, try to be nice to people, avoid eating fat, read a good book every now and then, get some walking in, and try to live together in peace and harmony with people of all creeds and nations.” I will gladly stand side by side with a religious person who is trying to do some good, but please spare me the kneel-before-the-lord-or-suffer-eternally-in-hell chicanery. Religious people have chosen to live by a protocol made by others. I have simply made my own protocol.

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Haskell: Using already computed part of list to compute further list

I faced a rather difficult (for a functional programming noob anyway) problem while coding in Haskell recently. Say I have a list which needs updating. Flex some FP muscles and you realise that if you have a function to update a single element, like:

updElem :: a -> a
updElem cur = --definition goes here

then the function to update the list of elements is simply defined as:

updList :: [a] -> [a]
updList = map updElem

Pretty simple. A basic observation here is that if we denote original list by Lo and updated list by Lu, then Lu[n] depends on Lo[n]. Now here’s the problem I faced. In my case, Lu[n] depended not only on Lo[n], but also Lu[n-1]. Not a big issue, I say, and proceed to redefine my updElem as

updElem :: a -> a -> a
updElem cur prev = --definition

And what about updList? It gets redefined thusly

updList :: [a] -> [a]
updList (prev:cur:[]) = [updElem cur prev]
updList (prev:cur:rem) = updElem cur prev : updList (cur:rem)

I gave myself 3 gentle pats on the back for coming up with this function and proceeded to test it out. It failed. Big time. Compiler having failed me, I resorted to my favorite debugger – pen and paper! I walked through each recursive call of updList and it wasn’t hard to see why it was bombing out – the pattern match is matching against Lo the whole time and I need my prev to come from Lu, not Lo.

Realizing the problem was but a small part of the solution. Fixing it is where the headache lay. Lu, while being created, needed reference to it’s own previous element to grow further. I guess the main reason I got stuck here was because I got thinking that I needed to access the stack of updList somehow since that is where the state of Lu will be stored while being created.

Several fruitless hours later, I gave up and sought help of the expert minds over at Stack Overflow. When I saw the solution posted there, I banged my head on the nearest wall for each pat I had awarded myself earlier, plus one. Picking up my jaw up from the floor, I proceeded to implement the simplistically brilliant solution which had totally eluded me so far. Here I present to you the final and correct version of updList in all it’s idiomatic glory:

updList :: [a] -> [a]
updList xs = zipWith updElem xs shifted
where shifted = 0 : updList xs

Where comes the magic number 0 from, you ask? Notice how in this entire post I have been silent about what element of the updated list Lu[0] depends on? Well it really depends on your problem. In my case, assuming it depends on 0 is works fine enough. Otherwise, if [a] is a list of your custom data types, perhaps you can introduce a null type constructor to replace the zero.

Installing and configuring dwm under Ubuntu

dwm is an ultra-minimal tiling WM written in C. Ubuntu offers a binary package, but it’s kind of pointless since the only way to configure dwm is by editing its source code and recompiling. Instead we will grab the latest source from the project website directly.

First install the dependencies needed for compiling dwm along with the package suckless-tools which contains a bunch of utilities for use with dwm.

$ sudo apt-get install build-essential libx11-dev libxinerama-dev sharutils suckless-tools

Now grab the dwm source code from the project website and extract it locally.

$ cd /usr/local/src
$ sudo wget http://dl.suckless.org/dwm/dwm-6.0.tar.gz
$ sudo tar xvzf dwm-6.0.tar.gz
$ chown -R `id -u`:`id -g` dwm-6.0
$ cd dwm-6.0

Before proceeding further with compilation, have a look at the README file. It tells you to modify the config.mk file to match your system. However the defaults work just fine on a normal Ubuntu system. So, go ahead and compile!

$ sudo make clean install

At this point, dwm is installed as /usr/local/bin/dwm, but you still need to add an entry for dwm so that it shows as an option in your login screen. For this we will install dwm from the repositories which, as I said before, is not of much use. But, it will also install a file /usr/share/xsessions/dwm.desktop which is what we need. So we will back up this file, remove dwm, and restore the backup file.

$ sudo apt-get install dwm
$ sudo cp /usr/share/xsessions/dwm.desktop{,.bak}
$ sudo apt-get purge dwm
$ sudo mv /usr/share/xsessions/dwm.desktop{.bak,}

Now we are all set to log in to our dwm setup! So log out and log back in to dwm session to be greeted with a shiny new desktop that looks something like this:

Default dwm under Ubuntu 11.10

Default dwm desktop

There you go, unabashed simplicity for you, right there. No oversized icons to waste screen space, no system trays, taskbars, panels to distract you and no apparent way to launch applications. What you do have is an narrow bar running along the top edge of the screen displaying some numbers and symbols with “dwm-6.0” written in the right corner. This bar is known as….we’ll just call it bar for now. Try pressing Alt+B to toggle the bar visibility. The numbers you see are virtual desktops (called tags in dwm) – dwm provides 9 of them by default. Try Alt+[Num] to switch between tags. The weird “[]=” symbol you see next to the tags is your current tiling layout. dwm offers three layouts by default – tile ([]=), monocle ([M]) and float (>). The “dwm-6.0” string you see in the far left can actually be changed to show useful information like current date, time, network status, battery status etc.

This is a good time to get yourself acquainted with dwm’s keyboard shortcuts. Remember, keyboard shortcuts are of prime importance in tiling WMs and you should know them as your life depended on it. You can configure them to your liking, but it helps to get acquainted with a few default ones:

Alt+Shift+Enter
    Launch xterm
Alt+Shift+C
    Kill a client (a window, if you must insist)
Alt+t
    Switch to tile layout
Alt+m
    Switch to monocle layout
Alt+f
    Switch to floating layout
Alt+b
    Show/hide bar
Alt+p
    Launch dmenu
Alt+[num]
    Switch to tag [num]
Alt+Shift+Q
    Quit dwm

dmenu is an application launcher from the author of dwm following the same minimalist philosophy as dwm. It is a part of the suckless-tools package we installed earlier.

Now we will try out the tiling modes of dwm. First close any open clients (Alt+Shift+C) and switch to tile mode (Alt+t). Now open up xterm using dmenu. Press Alt+p and you should see the bar get replaced by something like this

dmenu under Ubuntu 11.10

dmenu

Start typing the name of the app you wish to launch, and once dmenu has narrowed down the search, select it using arrow keys and press Enter. Launch xterm this way. It will occupy the entire screen. (Number 1 has been added by me)

single client open in dwm

Single xterm client.

Open another xterm client (using either dmenu or Alt+Shift+Enter). You will find the previously open xterm automatically resize and move to make space for this newly opened xterm.

two clients open in dwm

Two xterm clients.

Here, area 1 is called the master area and area 2 is called the stack area. The master area can hold a single client while the stack area holds all the remaining ones. Any newly opened clients always occupy the master area and the existing clients gets pushed into the stacking area. Open up a couple more xterms to see how it works You can switch focus between clients using Alt+j and Alt+k. Focused clients are denoted by a blue border while the rest have gray border. You can move a focused client from stacking area to master area using Alt+Enter. Play around with these shortcuts till you get the hang of how exactly the tiling works. Finally, you can change the ratio between master and stacking areas using Alt+h and Alt+l.

multiple clients in dwm

1 Client in master, 4 in stack with highly skewed area ratio

Now switch over to monocle layout (Alt+m) to have the focused client occupy the entire screen. Note how the “[]=” sign in the bar changes when you switch layout. This layout is equivalent to maximized windows in floating WMs. Note that Alt+j, Alt+k and Alt+Enter shortcuts will work in this layout too.

The final layout is the floating layout which is equivalent to your conventional floating WMs. Move the clients around using Alt+LMB+Drag and resize them using Alt+RMB+Drag. Note that you can switch individual clients into floating mode without affecting the layout of the rest by using Alt+Shift+Space. Floating clients always stay above the tiled ones.

Tags in dwm are a more powerful version of virtual desktops in KDE/Gnome etc. A client can have more than one tag associated with it and you can view all clients from any number of tags simultaneously. Use Alt+[num] to view all clients having tag [num], Alt+Ctrl+[num] to view clients having tag [num] in additon to currently visible clients, Alt+Shift+[num] to associate focused client to tag [num] and Alt+Ctrl+Shift+[num] to associate in addition to current tag associations.

There is still a lot more tweaking you can do before you using dwm as a full-fledged replacement for Unity. This includes configuring a system tray so you can use NetworkManager applet under dwm, displaying some meaningful information in the bar instead of the the curt “dwm-6.0”, configuring dwm by editing it’s source code (Have a look at /usr/local/src/dwm-6.0/config.h file to get started) and making your gnome themes and settings carry over to your dwm session (if you open any gnome apps at this point, they will have an ugly theme and unreadable fonts).

PS: Use “nautilus –no-desktop” in dmenu to launch nautilus, or else it will mess up your dwm session. A default rule in dwm specifies firefox should open in tag 9 by default. Happy tiling!

A quick way to determine endianness

One way is to write a C program that goes:

#include <stdio.h>
int main()
{
   unsigned int i = 1;
   char *c = (char*)&i;
   if (*c)
       printf("Little endian");
   else
       printf("Big endian");
   return 0;
}

Another way is to run a one-liner in your terminal. It goes:

[ "$(echo hi | iconv -t utf-16 | od -N2 -An -t x1 | tr -d ' ')" = "fffe" ] && echo "Little Endian" || echo "Big Endian"

It takes advantage of the magic number 0xFEFF that UTF-16 encoding adds before any text. Look here for more info.

DWM – Or how I learned to stop floating and love the keyboard

It began four years ago when I switched from XP to Ubuntu. It happened again two years ago when I migrated from Ubuntu to Arch. It repeated a year ago when I ditched KDE in favor of Openbox. Now, after twelve whole months of relative calm in the 1049088px digital utopia I had established using Openbox, XFCE4 Panel, Conky and a dozen cronjobs, a newer, more esoteric succubus is here to lure me away from my virtual Shangri-La. In just two weeks, it has already made me succumb to it enigmatic charms. I feel nauseated when faced with conventional floating window managers now, and make a mental note to sacrifice a baby in my dreams for each pixel I see wasted on petty trivialities like taskbars, titlebars, system trays, minimize buttons, maximize buttons, close buttons and other pointless doodads.

What is a tiling window manager (WM) anyway?

Let’s start with what a window manager is first. It is, as the name implies, a piece of software that manages all your open windows, nothing less nothing more. Whenever you perform an action on a particular window, like move, resize, minimize, maximize or close, you are interacting with a WM. Every OS running a GUI has a WM running too. Of course, presenting an end-user with just a bunch of windows to move around isn’t considered nice manners. Hence WMs are often relegated to being just another process in the system started alongside a myriad others to provide a nice and coherent and, not to mention, bloated experience to the user.

It shouldn’t come as a surprise that there is variety in WMs too. The ones that most people are used to, courtesy to them being default in Windows, GNOME, KDE and Mac alike, are called floating WMs. The title window “manager” is outright misleading here, since the actual window management is left to you, the user. It is you who has to manually move the window to desired position and resize it to the right size. The WM only remembers the position of the window and controls placement and ordering of newly opened windows. This works fine so long as you work solely with maximised windows. But try viewing more than one window side by side and the inherent shortcoming of the floating approach shines through.

As if moving and resizing to get the windows to fit without overlapping critical parts of each other wasn’t enough, you are forced to do it again for a newly opened window. And again for each new window you open! To add smelly icing to the crumbling cake, try closing a window now and scratch your sorry ass trying to fathom what good that gaping hole, about the same size as the one in your underwear, left on your desktop offering the world a peek at the aubergine panties of Jenna Jameson wallpaper, is for.

Enter Tiling WMs.

These WMs take a totally different approach to managing windows, in the sense that all windows belong to the same 2D plane. Basically, they abandon the faux-3D illusion of floating WMs (in which windows can overlap each other) and respect the fact that 2D surfaces (your monitor, in case you happen to be thinking about babies overrun by bulldozers) aren’t good for representing 3D.So, in tiling WMs, windows never overlap each other. Think about it. Most of the frustration of using a floating WM arises from the fact that non-maximised windows can – and will – overlap each other, forcing you to go through the resize-move-open-resize-move-close-resize-move-rinse-repeat rigmarole. These problem just doesn’t exist in tiling WMs.

This simpler mode of representing non-overlapping windows in one plane has an added benefit that each window can now be thought of as simple rectangular subsection of a larger rectangle. But what about those gaping underwear-sized wallpaper-exposing holes that are the bane of floating WMs? In tiling WMs, the holes are themselves guaranteed to be rectangles.And what do you put in a rectangle (besides a baby emerging from a bar soap manufacturing line)? Hint: it starts with a W, ends with a W and is not a wheelbarrow.

Since all windows and holes are rectangles, what is the point of having any holes at all? Why not let a window take the maximum dimensions it can take without overlapping other open windows? This is exactly what tiling WMs do, and is probably their biggest advantage too. They live up to their title of window “manager” in a way more glorious than floating WMs fail to. Not having to worry about rearranging windows each time a new one opens is a huge productivity booster once you have more than a couple open. You may feel a lack of control, what with your currently open windows suddenly moving and shrinking to make way for new one, or expanding to fill a void left by a closed window, at least initially. But trust the WM, it knows it’s job better than you do. You will be astonished to discover how much more effective this can be once you get over the getting-used-to phase.

Did I mention that all tiling WMs can be controlled entirely though the keyboard? Yup, they manage to totally circumvent the need for what is perhaps the most recognizable piece of desktop computing equipment ever – the ubiquitous-as-a-motherfuck – mouse! This ideology of ditching the pointy rodent in favour of its CTP-advancing cousin gels well with other stellar Unix applications like vim, tmux, the CLI itself and the excellent vimperator (or its newer cousin pentadactyl) add-on for Firefox.

DWM on Arch Linux

Which tiling WM you choose is purely a matter of personal preference. I chose dwm because it did the most of what I needed and none of what I didn’t. Here’s the last statement again with a bit more loquacity:

It’s Small

  • Weighing in at just under 41kb (compiled binary size), I have seen mere crash dumps of heavyweight programs with size greater than this thing

It’s a joy to configure

  • This depends on how well you know C, since the only way to modify any settings is by editing its source code and recompiling. While it may sound like a chore to recompile each time you make one small change, it also offers the freedom to customise in ways that a text-based config file just can’t

It’s fast and lightweight

  • “# init 5” will never be a reason to get a much-needed toilet break anymore!

Arch Linux offers a binary package for dwm, but it’s kind of pointless since you need the source code for configuring it. There’s also a couple of PKGBUILDs floating around in the AUR. But being the extraordinary piece of software that dwm is, it is only fitting to run it an extraordinary manner. So, I just have a .dwm directory in my home that contains the dwm source code and makefiles, along with my custom scripts and conky configs to run with dwm.

Configuring dwm is done by editing the config.h file (and, if you are feeling particularly masochistic, the dwm.c file). The file is commented well enough to make editing a trivial matter for people even remotely familiar with C. Note that you need to recompile and restart dwm in order for the changes to take effect. To make the process a bit less painful, first configure dwm to restart instead of exit on quit function is called. Start dwm from within a while loop inside your ~/.xinitrc or whatever script you use to start dwm:

while true; do
    dwm 1 &gt; ~/dwmlog 2 &gt;&amp; 1 || exit
done

Now make a shell alias for compiling dwm:

alias cdwm="pushd ~/.dwm; sudo make clean install; popd"

Replace ~/.dwm with whatever directory your source files are located in.
Now, just run cdwm followed by Mod+Shift+Q (or your custom keybind for quit function) to apply the changes without losing currently open windows.

In case you find that you need some functionality that dwm doesn’t provide, try searching for a patch before messing around with the dwm.c file. Good places to look for patches are:

Do browse through the links at the bottom of the dwm site for more dwm foo.

That’s about it! Happy tiling and baby-squashing!

Dark City, Dead Man, Black Metal

Hark, O’Nightspirit
Father of my dark self

In this post, black metal is used as a loose umbrella term. Whenever I use it, I could very well have meant death metal or post-metal or viking metal or folk metal and the meaning wouldn’t change one bit. Since BM is my first choice in metal, it gets preference over other extreme metal genres. The idea is to get people off phony twats like Justin Bieber and Taylor Swift and into actual music.

From within this realm, wherein Thou dwelleth
By this lake of blood,

From which we feed to breed

Music can work it’s magic in mysterious ways. What appears as mere noise and incoherent sound to some can be the most gratifying acoustic experience for others. Certain forms of music inherently lend themselves to this philosophy. Most of the music I listen to falls in this category. I have lost count of the times my co-passengers have begged for mercy to their ears when I put on some classic black metal while driving. It always makes me wonder: What is it about black metal (or death metal for that matter) that some people just plain fail to appreciate.? Enquiring about it yields the usual response, “This is no music, this is ear-splitting headache-inducing noise.”

I call silently for Thy presence,
As I lay this oath

Initially, I just labelled these people as lesser mortals with sub par taste in music. Now, actualising a handful of mainstream-to-underground success stories later, I believe there is still some hope left for these unbelievers. They only need to get over the initial hostility towards what isn’t pleasing at first sight (or in this case, hearing) to truly enjoy the beauty that lies hidden beneath. Once they do, there is no looking back. If grass were metal, it’d blacker this side of the fence.

May this night carry my will
And may these old mountains

Forever remember this night

Black metal is an expensive genre to get into.! It consists of lightning fast tempos, equally fast drumming, distorted guitars, high-pitched shrieks and screams and almost incomprehensible vocals, often simultaneously to create a barrage of sound so complex that only a really good set of speakers (or earphones) can do full justice to it. Coupled with the fact that most BM albums have less-than-average production quality, try listening on a cheap trashy gear and you will only hear half the instruments playing insipidly with occasional silly interjections in place of the nasty shrieks and screams. The earphones that ship with most PMPs are generally sacrilegious to the sanctity of black metal. So before getting into BM, do your ears a favour and get into a music store first.

May the forest whisper my name
And may the storm bring these words

To the end of all world

When listening to black metal, surrender yourself to the chaos. Lay down all your defenses and let the aural madness seep into every cell of your being. Let it assimilate with your blood and circulate to every inch of your body. Feel the auditory majesty of the music possess your physical self and control it like a puppeteer. Let the lyrics flow into your brain and saturate it with thoughts of ancient epic battles and human sacrifices inside cavernous fire-lit caves and an inescapable sense of impending doom. Casual listening is an exercise in futility. Black metal reveals it’s true form only to those who seek it with a devoted ear.

May the wise moon be my witness
As I swear on my honour
In respect of my pride and darkness itself

That I shall rule by the blackest wisdom

Once you get over the initial hiccups to become a “tr00 m3t4lh34d” and a “h4rdc0r3 h34db4ng3r”, you will discover that there exist more metal bands out there than you can listen to, even if you pick a new one each day till you perish. Head over to Encyclopaedia Metallum to know the exact numbers (78217 metal bands as of today). Figuring out the truly good ones can become quite a daunting task. Going by the general opinion and ratings doesn’t help much either since the hype surrounding some bands (Mayhem, I am looking right at you) has reached such epic proportions that the fanboys will have you believe their band’s music is the best thing since protected sex. So, I will post a few bands here that I believe are truly deserve all the accolades they get along with my favorite album from them.

O’Nightspirit
I am one with thee
I am the eternal power
I am the Emperor.!

1. Emperor

Anthems to the Welkin at Dusk

Anthems to the Welkin at Dusk

Genre : Black Metal

The fact that I intersperse the lyrics from the opening track (Al Svartr) of this album with this post should itself speak about the high regards in which I hold this masterpiece. The second track – Ye Entrancemperium – starts with the fastest fucking riff I have ever heard, and ends with an even faster one.! Nothing like this album to get your blood pumping and testosterone levels high. This album along with the equally magnificent “In The Nightside Eclipse” cements Emperor’s place far above their contemporaries in Black Metal in my collection.

Recommended Albums:

  • Anthems to the Welkin at Dusk
  • In The Nightside Eclipse

2. Burzum

Hvis Lyset Tar Oss

Hvis Lyset Tar Oss

Genre: Black Metal

One-man project by the most notorious man in the history of Metal, Varg Vikernes. He murdered a fellow band member by stabbing him 23 times, set ablaze atleast three Christian churches in Norway, is a self-proclaimed racist and a neo-Nazist and has been sentenced to 21 years in prison. But who cares as long as he produces albums like “Hvis Lyset Tar Oss”. It consists of four songs, two of which (the title song and Inn I Slottet Fra Drommen) are mediocre, one of which (Tomhet) is intensely atmospheric and breathtakingly beautiful while the fourth one (Det Som Engang Var) is heralded by many as the song Burzum was born to write. His vocals sound like a cross between the helpless cries of a man set on fire and an ancient feral ghoul.

Recommended Albums:

  • Hvis Lyset Tar Oss
  • Filosofem

3. Moonsorrow

Verisäkeet

Verisakeet

Genre: Folk Metal + Black Metal

Not strictly Black Metal, as the band combines the choruses of good ol’ folk music with the brutality of metal. They prefer to call their sound “epic heathen metal”. But genres be damned.! This is one of the most epic and inspiring albums I have had the pleasure of listening. By inspiring, I mean the kind of feeling that makes you want to assemble a bunch of friends and start your own band to perform live in front of 10,000 roaring fans. The melodies here stick with you for a long time, and since you can’t really hum them (trust me, I have tried), you just end up listening to the album again and again. Words fail to do justice to the feeling of epicness this album generates. It is one of the must-listen-before-you-die albums for fans of any genre of music.

Recommended albums:

  • Verisäkeet
  • Kivenkantaja

Other bands that I listen to include:

  • Opeth
  • Cult Of Luna
  • Isis
  • Mayhem
  • Agalloch
  • maudlin of the Well
  • Rudra
  • Ulver

The above list should keep you busy for a few months. Metal is a kind of genre that has many talented and skilled bands that are yet to have there big break into the limelight. Sites like Encyclopaedia Metallum and Youtube are great places to discover such unearthed gems.

Winds and storms, embrace us now
Lay waste the light of day
Open gates to darker lands
We spread our wings and fly away.!

DSDT editing: Put an end to your ACPI woes

Background:

Ever since I installed Openbox, one of the major frustrations was the fact that it started up with display brightness set at 100%. It wasn’t an issue in either KDE or Windows whose respective power management profiles did the job for me. Since I don’t use any sort of power management program in Openbox, manually setting the brightness to a saner level using brightness keys each time was a pain. For a while, I resorted to an ugly “hack” of sorts : a script that wrote brightness value directly to relevant file in /sys (in my case it is /sys/class/backlight/acpi_video0/brightness). Here is the script:

#! /bin/bash
# The value 15 is obtained from
#`cat /sys/class/backlight/acpi_video0/max_brightness`
function usage()
{
  echo -e "Usage : $0 <value>\n"
  echo -e "<value> is an integer between 1 and 15\n"
}
case $1 in
[1-9]|1[0-5])
  echo $1 > /sys/class/backight/acpi_video0/brightness;
*)
  usage;
esac

I call it an ugly hack because

  1. It requires root access to change brightness
  2. It needs to be set up to execute on start of each DE/WM separately.

I needed a more “universal” and elegant solution than having supuser access just to change brightness.

The dmesg output on my machine contained an error that caught my attention:

[Firmware Bug]: ACPI: No _BQC method, cannot determine initial brightness

Poring through the ACPI Specs (which contains a wealth of information for those willing to sift through all the 700+ pages), I found out that my salvation lay in DSDT editing.

For the unitiated:

ACPI is to laptop users what oxygen is to mankind. BIOS, by itself, provides very basic support for all the hardware typically found inside a laptop. It cannot, for example, handle what happens on opening/closing the laptop lid, plugging in/out the the AC adapter, pressing the brightness keys etc. Sleep and hibernate are two essential features for any laptop user which are too complex for BIOS to handle. All these laptop-specific tasks are instead handled by ACPI. The biggest advantage of ACPI is that it is OS-agnostic. So, ACPI features that work flawlessly on Windows can be almost always expected to work on Linux (the almost part will be explained in a moment).

DSDT is a table that describes the ACPI properties and functions of all your hardware. If certain ACPI feature is missing or functioning improperly on your laptop, you can safely put the blame on a badly coded DSDT. DSDT is written in a language known as ASL (ACPI Source Language) that looks at lot like C. Just like C, it needs to compiled before it can be used by the system. This is where the problem creeps in. ASL compilers are provided by Microsoft and Intel. Like all things Microsoft, their compiler is far too lenient when it comes to ASL syntax compared to Intel’s. Hence, DSDTs compiled using MS compiler are generally buggier and more problematic than Intel-compiled ones. Windows includes all sorts of hacks to mask the ineffectiveness of the MS compiler while Linux typically suffers in some way or the other (laptop not sleeping/hibernating, fan spinning constantly, brightness keys not working etc.).

Lament not, you can extract the DSDT of your system, edit it to fix the errors, and replace the original DSDT with the fixed one to resolve most issues.

Working with the DSDT:

Grab the latest copy of the Intel ASL Compiler from your distro repositories or the source code from here.

Extract the DSDT of your system:

$ sudo cat /sys/firmware/acpi/tables/DSDT > dsdt.aml

Decompile the extracted DSDT:

$ iasl -d dsdt.aml

This will generate a dsdt.dsl file that you can open in any text editor and start editing. But it’s a better idea to recompile the file to see if it produces any errors

iasl -tc dsdt.dsl

On my laptop, it produces following output:

$ iasl -tc dsdt.dsl

Intel ACPI Component ArchitectureASL Optimizing Compiler version 20110112-64 [Jan 20 2011]Copyright (c) 2000 - 2011 Intel Corporationdsdt.dsl 4119: 0x00000000, // LengthError 4122 - ^ Invalid combination of Length and Min/Max fixed flags

dsdt.dsl 4133: 0x00000000, // Length

Error 4122 - ^ Invalid combination of Length and Min/Max fixed flags

dsdt.dsl 8951: Name (_T_1, Zero)

Remark 5111 - Use of compiler reserved name ^ (_T_1)

dsdt.dsl 8952: Name (_T_0, Zero)

Remark 5111 - Use of compiler reserved name ^ (_T_0)

dsdt.dsl 9009: Name (_T_1, Zero)

Remark 5111 - Use of compiler reserved name ^ (_T_1)

dsdt.dsl 9010: Name (_T_0, Zero)

Remark 5111 - Use of compiler reserved name ^ (_T_0)

dsdt.dsl 9091: Name (_PLD, Buffer (0x10)

Error 4080 - Invalid object type for reserved name ^ (found BUFFER, requires Package)

dsdt.dsl 9153: Name (_T_1, Zero)

Remark 5111 - Use of compiler reserved name ^ (_T_1)

dsdt.dsl 9154: Name (_T_0, Zero)

Remark 5111 - Use of compiler reserved name ^ (_T_0)

dsdt.dsl 9211: Name (_T_1, Zero)

Remark 5111 - Use of compiler reserved name ^ (_T_1)

dsdt.dsl 9212: Name (_T_0, Zero)

Remark 5111 - Use of compiler reserved name ^ (_T_0)

dsdt.dsl 9288: Name (_PLD, Buffer (0x10)

Error 4080 - Invalid object type for reserved name ^ (found BUFFER, requires Package)

dsdt.dsl 9305: Name (_PLD, Buffer (0x10)

Error 4080 - Invalid object type for reserved name ^ (found BUFFER, requires Package)

dsdt.dsl 10489: Name (_T_2, Zero)

Remark 5111 - ^ Use of compiler reserved name (_T_2)

dsdt.dsl 10490: Name (_T_1, Zero)

Remark 5111 - ^ Use of compiler reserved name (_T_1)

dsdt.dsl 10491: Name (_T_0, Zero)

Remark 5111 - ^ Use of compiler reserved name (_T_0)

ASL Input: dsdt.dsl - 12135 lines, 370000 bytes, 4042 keywords

Compilation complete. 5 Errors, 0 Warnings, 11 Remarks, 10 Optimizations

5 errors and 11 remarks. How you go about resolving these errors if a matter of personal preference. You can search the internet for the error number, which helps most of the time. Or you can actually try learning ASL from the ACPI specs and then get down to the debugging business, like real men do.

Here’s how I fixed my DSDT:

Error 4122: http://www.insanelymac.com/forum/lofiversion/index.php/t189272-100.html

Remark 5111: Replace all instances of _T_# within scope (i.e. within a pair of curly braces) by T_#

Error 4080: Unsolved, but not critical.Apparently, the kernel takes the remedial measure when it encounters this error http://lists.acpica.org/pipermail/devel/2010-July/000164.html

Once the DSDT was clean, it was time to get back to the original problem. As the dmesg output clearly stated, the method _BQC had not been defined in my DSDT at all. Fortunately, it was a simplistic method that merely returned one of the values specified by the _BCL method. I defined it in the Device (LCD) section after the _BCL method:

Method (_BQC, 0, NotSerialized)
{
    Return (0x1E)
}

This corresponded to the brightness level 5 of the “ugly hack” described above. Once finished, it was time to make my laptop use the fixed DSDT instead of the old one. The general steps to do so are explained here. Arch Linux users can follow the ABSmethod to recompile the kernel instead. Note that recompiling the kernel is the only way to do it in Arch, and it can take a good 30-45 mins of fast-scrolling gibberish on the terminal on a decent-spec PC.

Once the “fixed” kernel was compiled and bootable, I had the simplistic pleasure of staring into the LCD screen that didn’t blind me each time it turned on,  and geek’s satisfaction of running a clean DSDT … atleast till the next kernel update!