1. Computers
  2. Display Drivers
  3. Graphics Cards
  4. Memory
  5. Motherboards
  6. Processors
  7. Software
  8. Storage
  9. Operating Systems


Facebook RSS Twitter Twitter Google Plus


Phoronix Test Suite

OpenBenchmarking.org

Booting A Modern Linux Desktop In Just ~200MB

Tomas Matejicek

Published on 26 December 2012
Written by Tomas Matejicek
Page 1 of 3 - 10 Comments

Unlike many of the Linux distributions out there today that are little more than minor user-facing changes to Ubuntu or another tier-one Linux operating system, Slax for the past many years has followed its own dance. Slax, a LiveCD Linux distribution built around Slackware, is very lightweight and calls itself a "pocket operating system" as with the most recent release it can fit a full Linux OS with the KDE4 desktop in about 200MB. Slax is also intended to be quite easy for others to modify and create custom images via Slackware packages and Slax modules. The recent Slax 7.0 release was the first update for the open-source operating system in several years. For those interested in knowing how this very lightweight and customizable operating system can work so efficiently, Tomáš Matejícek, the Slax creator, has written an exclusive Phoronix article about the process.

What Is Slax

Slax is a Live operating system based on Linux. Live means it runs from an external media without any need for permanent installation. Slax boots from USB mass storage devices such as Flash Drive keys as well as from regular hard drives and CD/DVD discs.

Slax Directory Structure

All Slax data files are located on the boot media in a single directory. It is no surprise that the name of that directory is 'slax'. All the magic happens inside. Here is an overview of simplified directory structure; directories are red, some interesting files are mentioned as well, using italic:

Booting The Linux Kernel

When your computer's BIOS boots Slax, it actually just runs SYSLINUX boot loader. The boot loader itself is stored either in file isolinux.bin or ldlinux.sys, depending on your boot media - CD/DVD uses isolinux.bin, USB disk or hard drive uses ldlinux.sys.

As soon as the SYSLINUX boot loader is executed, it learns what to do next from its configuration file (you guessed it) syslinux.cfg. In Slax, this configuration file contains instructions to show some cool boot logo and optionally provide boot menu if the user hits a key before timeout. When the timeout counter reaches zero or the user exited boot menu, SYSLINUX boot loader loads two files into memory: vmlinuz (Linux kernel) and initrfs.img (base root filesystem). The progress is indicated by continuous stream of dots printed on screen. Once the files are loaded, the vmlinuz binary is executed to start the Linux kernel.

Pre-Init

Under normal conditions (when a standard Linux distribution is starting from a hard drive), the Linux kernel would mount the root filesystem from the hard drive and /sbin/init would be executed as the main process which takes care of system startup. In Slax, the situation is different - there is no hard drive to mount the root filesystem from, yet the kernel surely needs some init process to be started. For that purpose, Slax carries a base filesystem in the initrfs.img file - it is a compressed CPIO archive with some directories and files inside, including core Linux tools (commands) and the desired init.

So after the Linux kernel has successfully initialized and has a full control of your computer, its last task is to find the mentioned CPIO archive in memory (it was loaded there from file initrfs.img by syslinux boot loader as you surely remember), extract it (into a memory area which acts as a temporary root filesystem, called initramfs) and execute the temporary /init process from there.

<< Previous Page
1
Latest Linux Hardware Reviews
  1. AMD Radeon R9 290: Gallium3D vs. Catalyst Drivers
  2. AMD Radeon R9 290 Open-Source Driver Works, But Has A Ways To Go
  3. Trying The Configurable 45 Watt TDP With AMD's A10-7800 / A6-7400K
  4. Sumo's Omni Gets Reloaded
Latest Linux Articles
  1. 20-Way Radeon Comparison With Open-Source Graphics For Steam On Linux Gaming
  2. Preview: OS X 10.10 Yosemite vs. Ubuntu Linux GPU Performance
  3. Radeon Graphics Yield Mixed Results With Linux 3.17 Kernel
  4. AMD's RadeonSI Driver Sped Up A Lot This Summer
Latest Linux News
  1. Nouveau On Oibaf PPA Is Back To Running Well
  2. Metro 2033 Redux Will Hopefully Hit Linux Real Soon
  3. New Virtual Monitor Software Might End Up On Linux
  4. Company of Heroes 2 Might Be Coming Out For Linux
  5. NIR Still Being Discussed For Mesa, LLVM Gets Brought Up Again
  6. Plasma Active Is Mostly Ported To KDE Frameworks 5
  7. Google Chrome 37 Brings Many Security Fixes
  8. MenuetOS Updated With SMP Threads & Onscreen Keyboard
  9. Mesa Has A New Release Manager
  10. Enlightenment E19 Lands Its New Wayland Compositor Code
Latest Forum Discussions
  1. AMD Releases UVD Video Decode Support For R600 GPUs
  2. Announcing radeontop, a tool for viewing the GPU usage
  3. Updated and Optimized Ubuntu Free Graphics Drivers
  4. [DB] BIOS - ACPI - data collecting
  5. It's Now Possible To Play Netflix Natively On Linux Without Wine Plug-Ins
  6. Users defect to Linux as OpenBSD removes Lynx from base system
  7. Chinese People Try To Patent Wine On ARM
  8. American Citizens running AMOK for food stamps