User:Softcraft/Sandbox

Generations Linux is a binary Linux distribution incubated in the late-1990s, created and maintained by Mauro DePalma. In its present form it is a live/boot CDROM. The technology used can be described as a multi-stage boot sequence.

The first stage of the boot sequence is loading the Linux kernel. The default is to use root=/dev/ram0 as the root filesystem, that is to say that a compressed disk image (aka: ramdisk) found on the CDROM media itself and uncompressed onto memory for system initialization (second stage) following immediately a successful stage one. Generations Linux specific and other advanced boot options for Linux kernel version 2.6 series must be passed on the command line prior to the start of loading the kernel. By default the boot sequence starts automatically within 30 seconds, unless there is keyboard activity.

1. ISOLINUX - A bootloader for Linux using ISO 9660/El Torito CD-ROMs from H. Peter.

2. The second stage is System V process control initialization by Miquel van Smoorenburg with a startup script inspired by the KNOPPIX Linux distribution by Klaus Knopper. The command interpreter shell and initial runtime environment is provided by the BusyBox by Erik Andersen.

3. The startup script looks for the ''/generations/linux SquashFS (a highly-compressed file system for Linux by Phillip Lougher) image file which would occupy approximately 1.9GB uncompressed.

4. After mounting the SquashFS image as /install, Unionfs (developed at Stony Brook university since 2004) is mounted on /vortex, coupled with the root directories (/bin, /sbin, /usr, ..) being references (read: links) to the /vortex/<> conterpart, we have the luxury of a writable system.

5. Unless otherwise specified, the default runlevel is runlevel 4, which Generations Linux defines as autologin as guest and enter a single X Window System session.

6. There are exactly two interactive usable logins on the Generations Linux live CDROM: 6.1 The system administrator root (password: admin) super user login. 6.2 The guest (password: welcome) account login, with super user (sudo) privileges only for system shutdown and changing system runlevel.

6.3 System V runlevels:
 * 0 - halt (power down)
 * 1 - Single user mode
 * 2 - Multiuser without server class services (same a runlevel 3, if you do not have networking)
 * 3 - Server class multiuser mode
 * 4 - unused [Generations Linux autologin into a single X Window session]
 * 5 - X11
 * 6 - reboot

7. On Generations Linux when running from the CDROM media before entering a runlevel and only once a special /etc/init.d/autoconfig script (also inspired by KNOPPIX) does hardware detection and populates the /etc/sysconfig directory with individual files each dedicated to provide parameters for the hardware found. Entering and leaving a runlevel consists of executing one or more scripts for that runlevel. We introduced a convinience /etc/sysconfig/services file which lists services common to runlevels 2 through 5.