This page explains what the Slinky installer is, how it works internally, and (in the future), how to modify it or handle some corner cases which may require slinky patches. All the step-to-step information on how to install Red Hat Linux with Slinky, or other RULE tools, is availablein the RULE install guide.
This document has been created by M. Fioretti on 2003/02/23 on the basis of the Slinky v0.3.6 README file created on 2003/01/01 by M. Fratoni. Update 2003/07/15: The currently latest version of slinky is 0.3.96, releases on June 12, 2003. The main changes are:
- Script cleanup to make some prompts less ambiguous.
- Added the setterm binary to the install.
- Modified the initscripts to turn off console blanking during the install.
- Added several virtual console capture device files. We can now do console screen capture. (To capture output on VT1: cat /dev/vcs1 > out.file(from VT2, obviously)).
- Added ‘eject’ binary to installer filesystem. The Boot CD should now be auto ejected.
- Removed support for 7.x versions going forward.
- Added config file support to allow formatting “/” WITHOUT further prompting. Be careful.
Overview
Slinky is an installer for Red Hat Linux based on BusyBox, i.e. built on a home brewed boot/rescue floppy. Slinky can work in as little as 8M of RAM. This makes possible to install the same standard packages of Fedora Core on limited hardware. Slinky is also used in SlinkyDetect.
To install Fedora with Slinky you also need to have the usual Fedora Core Cd-Roms, or at least the same packages available through the network. Possible install modes are: local cdrom, nfs mounts, local disk iso image, local disk rpms, http, and ftp.
The floppy loads a minimal Linux system and an installation script is used to install the requested packages to disk. The script prompts for user input to handle tasks such as partitioning the disks, locating installation media, and selecting package groups for installation. The majority of the promps request ‘yes/no’ answers, or provide a list of answers the installer knows about.
Slinky does not do everything that Anaconda does, but it does install a working system. On first boot, kudzu runs, which handles the hardware detection that the installer skips. On oddball hardware, slinky can be a little challenging to get working. Michael and others managed to use it without difficulty on several laptops and various boxes from P-100 to an Athlon 2600. Slinky is basically a set of scripts that do the installation and configuration, prompting the user for info when decisions are needed. It can use a config file that does away with most of the prompts. Slinky can also use optional disk containing drivers for hardware that must be accessed during installation.
With Slinky, both fdisk and cfdisk are available for the partitioning task. A ‘/’ partition and a swap partition are required, while other partitions are optional. Currently at version 0.3.95, slinky can boot in as little as 6 MB of RAM, but installation requires 8 MB. At 8 MB, on a Pentium 200, the base install is complete in well under an hour.
Currently, slinky is limited to IDE drives, and while loadable modules are available for oddball hardware, some linux knowledge is required to get the modules loaded and the devices properly configured at install time. After the install, ‘kudzu’ is run on boot up, and detects and guides the user through configuration of any hardware found. The slinky installer currently consists of:
- The boot image, slinky-[$version].img,
- The second stage image, disk2.img, and
- An optional disk containing drivers for hardware that must be accessed during the install. (For example, older soundblaster cdroms that require the sbpcd module)
- Either disk 1 from The Red Hat cds, or a disk containing updated versions of the packages in the install lists.
Slinky internals
The installer is simply a shell script that allows Red Hat Linux 7.2, 7.3 or 8.0 to be installed in 8M of RAM. You will need either Red Hat Linux {$version} disk 1, or an image of Red Hat disk 1 on a local hard drive. Red Hat Linux 7.3 and 8.0 require both disk 1 and disk 2.
If you can burn the ISO image to CD and boot from it, then the install will be reasonably straight forward, otherwise, please check the README file for the version of Slinky that you used, and ask for support on the RULE list. A large subset of kernel modules is available at http://www.tuxfan.homeip.net:8080/rule/slinky/2.4.18-4RULE/ or, if you are using the ISO image, is included in the modules directory. To load them, run the command insmod /mnt/cdrom/"module-name
Slinky uses some variables which can be defined in a file called ‘slinky.config’ The floppy images contain a slinky.config.sample file for reference.
Supported install modes
Possible install modes are: local cdrom, nfs mounts, local disk iso image, local disk rpms, http, and ftp. The first script (to be) used by slinky is scripts/setup.sh. The scripts used for network installs is init_network.sh, which should be edited to suit your needs. (See the RULE Install Guide.
The “pivot root phase”
The installer boots into a limited linux environment. Once partitioning has been done, the installer mounts the newly created partitions, and executes a “pivot_root”. The newly created partitions become the new / directory. This is similar to the way the kernel loads an initrd.img as “/”, then does a pivot_root into the real “/” filesystem.
In this way, the installer has access to utilities as they are installed. For example, the base installer lacks the lilo andpasswd utilities. However, both are installed from rpmpackages during the installation. By the time the installerneeds them, both are available.
Slinky Developer Resources
- Complete Slinky Block Diagram (PDF) by F. Zahaurek
- Slinky Customization Guide
- Slinky page of F. Zahaurek: contains install notes on Slinky for Fedora Core 4 and older versions. Eventually everything there should be migrated here
Don’t forget Slinkydetect!
A very useful Slinky offspring: a bootable floppy for automatic hardware detection and inventory. Perfect to collect data for used hardware databases. To know more and download it, please visit the Slinkydetect page on this website.
Credits
Slinky was originally written by M. Fratoni, who also created the first RULE installer, Miniconda. Later on development was resumed by F. Zahaurek, with assistance and testing from all the other RULE members. Many thanks to Michael and Franz for all their work: without them RULE would have never existed and continued to be useful. – M. Fioretti