DietLinux -- Documentation

1. Introduction
2. Boot / Installation
   • General
   • boot/rescue-floppy
   • boot/rescue-CD
3. Setup
   • Users
   • Hostname
4. System daemons
   • Daemontools
5. Networking
   • NIC configuration
   • SSH client and server
   • Mailserver (qmail) configuration
   • DNS (tinydns) configuration
6. FAQ

Introduction

DietLinux is a distribution based on dietlibc. It contains a 2.6.x linux kernel, and will never support older kernels that do not support for devfs and tmpfs. The boot process is optimized for small size, the upcoming 0.2-release should be able to boot from cdrom, floppy or usb-stick on all systems with at least 8mb of RAM.

I'm currently rewriting the documentation from scratch -- it was pretty much outdated and did not match my working copy at all. The new init system works under ideal conditions, and I'll be able to put up a preview cdrom pretty soon. It was just quite pointless to keey the old documentation up.

Boot

General stuff

With the upcoming 0.2-release the boot-process is the same for all media. I got rid of ramdisk images for the root filesystem completely, and shrinked the initrd-images to about 60k (uncompressed). A kernel can be used with the boot system if it has support for initrd, tmpfs and devfs.

You need to configure the bootloader to give the kernel some bootparameters:

init=/linuxrc

We use linuxrc to set up some stuff. It will execle() init later

root=/dev/ram0

The initrd is the final root. Though our linuxrc will change it.

devfs=mount

Only needed if you didn't tell the kernel at compile time to automatically mount devfs

bootdevice=[]

To come, hints for linuxrc from which device we booted

Bootup, the initrd phase

linuxrc, stage 1

The first part is handled in linuxrc. I'ts described here short for better understanding what's going on.

• linuxrc gets started by the kernel. Besides linuxrc we have two directories in our ramdisk -- /dev with mounted devfs and /rootfs
• linuxrc mounts a tmpfs at /rootfs
• linuxrc creates basic directories in the rootfs (namely dev and initrd)
• linuxrc chdirs to /rootfs, calls pivot_root and chdirs / chroots in the new root. After this we have the old contents of the initrd under /initrd
• linuxrc remounts initrd/dev under /dev, and mounts /proc. With the dev remount we've put the open /dev/console file into the right filesystem.
• linuxrc umounts /initrd with MNT_DETACH set. Most likely initrd will not unmounted immediately but when calling execle() to exec init

For more details please consult the apkg sources.

linuxrc, stage 2

We're now getting to the second stage, still powered by initrd. That's the first stage you can influence without modifying the linuxrc-sources.

• linuxrc creates all directories in the rootfs
• linuxrc mounts procfs and sysfs
• linuxrc inits the built-in packagesystem. This includes trying to find a (a dietlinux media must have a file called `dietlinux-media' in its root) es well es the name of the initial package to load (from dietlinux-media)
• linuxrc loads the initial package (the apkg package system) and execl()s apkg with param -t (starts bootstrap). Most likely /initrd gets freed here, so we have about 60k additional space from now on.

apkg stage

Now it's apkgs turn to bootstrap a package set to the rootfs

FAQ

Getting Information

There is currently one mailinglist for dietlinux. To subscribe, send an empty email to dietlinux-users-subscribe@lart.info

Versions

DietLinux version numbers are similar to the one of the Linux kernel: [major].[minor].[patchlevel], versions with even minor numbers are called `stable'. There is a rough `roadmap' for the stable versions, unstable subversions will be released every time I think I finished one of the things wanted for the next stable. Please note that an unstable version is constantly changing, while every change in a stable results in a new patchlevel number. Patchlevels in stable mean bugfixes, no new features.

The current unstable version is 0.1.1, 0.1.2 will be released soon and contain mainly a small but complete rescue system.

0.4	complete rescue-system; selfhosting (i.e., contains gcc-toolchain, you can compile the whole system from CD-ROM); contains a ports-tree with all software used on the CD-ROM; contains a simple package system; may contain a bootloader that can be installed on harddisk (maybe grub); may contain a simple shellscript to copy all needed files to harddisk;
0.6	Contains grub as a bootloader; contains a tool for harddisk-installation;
1.0	Contains dietlibc 1.0

• Why is it named '`DietLinux', and not `GNU/DietLinux' or similar?
  The most important reason: Because most of the userland is not from GNU. Judged by the importance/amount of software, I had to call it `Fefe/DietLinux' or `djb/DietLinux'. (Note: if one of the persons mentioned cannot live withou having their name in here, please drop me a note)