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Kernel module edition of the Cycles Per Instruction (2014) album.
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Latest commit c8798d6 Apr 28, 2014 @dbalatero dbalatero Update README.md

README.md

♫ netcat - Cycles Per Instruction

by Brandon Lucia, Andrew Olmstead, and David Balatero

Released April 2014

Cycles Per Instruction - The Kernel Module Edition

Welcome to the most unnecessarily complicated netcat album release format yet.

In this repository, you will be able to compile your own kernel module, create a /dev/netcat device and redirect its output into an audio player (tested with mplayer and play from SoX as well).

ogg123 - < /dev/netcat

This repository contains the album's track data in source files, that (for complexity's sake) came from .ogg files that were encoded from .wav files that were created from .mp3 files that were encoded from the mastered .wav files which were generated from ProTools final mix .wav files that were created from 24-track analog tape.

If complexity isn't your thing, you can go to our webpage and follow the links to a digital download or a cassette tape of our album.

Building

We've only tested this on Ubuntu Linux. Sure, it's real easy to grab another operating system ISO and test it out, but after a day toiling in the bitmines, who has the energy?

Other people report:

  • @NicolasCARPi says it works on Arch 64-bit / kernel 3.14.1-1-ARCH. @diogoff shows you how to do it
  • Intrepid explorer @jfilip feels good about his 64-bit Fedora 20 install
  • @silviuvulcan Reports that we're up and running on slackware64-current
  • @alinefr did make a howto explaining how she is enjoying netcat in her Gentoo Linux. She also explained how she did a http streaming from /dev/netcat to listen from MPD and possibily from any open source audio player.
  • @pah got it running after increasing the Vmalloc limits to vmalloc=192M on a 32-bit i686 Debian machine (3.13-1-686-pae).
  • @g0hl1n reports that it works on Debian 7.4 "wheezy" / Linux 3.2.0-4-amd64 #1 SMP Debian 3.2.54-2 x86_64 GNU/Linux
  • @ciderpunx can compile and run it on Debian 8.0 "Jessie" / Linux 3.12-1-amd64 #1 SMP Debian 3.12.9-1 (2014-02-01) x86_64 GNU/Linux
  • @f00stx slung some bits all the way from Brisbane, Australia to bring you a FreeBSD version (which he compiled on a G5 Mac, no less!) Check it out here.
  • @dyfer had the foresight to save up all his turbo boost, so he could dunk a Linux Mint 16 √ report from half-court

First, install some dependencies:

sudo apt-get install build-essential vorbis-tools linux-headers-$(uname -r)

Check out the repo:

git clone https://github.com/usrbinnc/netcat-cpi-kernel-module.git
cd netcat-cpi-kernel-module

Next, build the module by running:

make

Building will take a long time. Hang with it. Building also requires several gigabytes of memory. We're not totally sure why, but we think it is because the compiler is making lots of copies of several large, static arrays that contain track data.

Listening

After you build, you need to load the module and see if it is working, so you can run:

sudo insmod netcat.ko
dmesg

You should see output like the following from dmesg:

[ 2606.528153] [netcat]: netcat - Cycles Per Instruction - Kernel Module Edition - 2014
[ 2606.528153] [netcat]: netcat is Brandon Lucia, Andrew Olmstead, and David Balatero
[ 2606.528153] [netcat]: 'ogg123 - < /dev/netcat' to play.

Finally, put on some headphones, and run:

ogg123 - < /dev/netcat 

Track information will show up in the output of dmesg:

[  612.411529] [netcat]: Now playing track 2 - The Internet is an Apt Motherfucker

If you've read this far, god help us all.

Troubleshooting

ERROR: could not insert module netcat.ko: Cannot allocate memory

Loading the module may fail due to kernel memory allocation limits:

insmod: ERROR: could not insert module netcat.ko: Cannot allocate memory

also indicated by the errors like the following in dmesg:

[195207.149213] vmap allocation for size 37806080 failed: use vmalloc=<size> to increase size.
[195207.149216] vmalloc: allocation failure: 37798136 bytes
[195207.149217] insmod: page allocation failure: order:0, mode:0xd2

This can happen especially on 32-bit kernels. The Vmalloc limit can be increased by passing vmalloc=<size> to your kernel command-line (typically 128Mb on 32-bit kernels, increasing it to vmalloc=192M should be sufficient). Some information how to overcome this problem can be found in the MythTV wiki.

People insane enough to contribute (thanks!!)

  • @mark-bi added support for auto-creating our /dev/netcat device. Thanks, Mark!
  • @arfar pointed out that not everyone wants to clone public repos over SSH, and updated the clone instructions to https. Thanks!
  • @jmtd simplified the command to play audio by removing the extra instance of cat. Thanks!
  • @gregkh for making our module coherent with standard Linux style and cleaning up some other loose ends.
  • @silviuvulcan for testing with vlc and finding that we run and build on slackware64-current. Thanks!
  • @pah dropped some knowledge for anyone struggling in the streets with 32-bit kernels and vmalloc limits
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