User:SwifT/Complete Handbook/Versions media installation concerns

Gentoo versions
One of Gentoo's major advantages is that it does not really know versions. Once installed, the user has a Gentoo installation, not a Gentoo 2005.1 or 2004.3 installation. Therefore users will continue to benefit from the Gentoo development with every system update performed - there is no need to run through a specific upgrade procedure every time Gentoo makes a new release.

This is also reflected by the pace at which Gentoo provides new installation media: through an auto-build process, new media are provided on a weekly basis (for active architectures). These auto-builds contain all the necessary media to install Gentoo with, and is also the medium that we will use throughout this handbook.

Gentoo LiveDVD releases
Occasionally, Gentoo will create a Gentoo LiveDVD from which one can play with Gentoo before installing it. These releases are announced on the main Gentoo website.

The structure of a Gentoo Linux installation
Understand that the Gentoo installation procedure is quite different from most other Linux distributions: where other distributions try to perform most steps for the user, Gentoo Linux asks the user politely (but firmly) to do things actively.

Getting the hardware up and running, configuring the network, partitioning the disk(s), copying over the initial files, building additional software (including the kernel), ... all these steps should be performed before one can finally boot in a minimal Gentoo environment. Not that all these steps can't be automated (Gentoo even offers tools to automate a few of those steps and there might still be a few unofficial installers that automate most - if not all - steps) but by documenting these steps in great detail Gentoo almost forces the user to learn various Linux-related procedures.

The structure of a Gentoo installation is as follows:


 * 1) Download and boot a bootable system from which Gentoo can be installed
 * 2) Prepare the disk(s) and partitions to host Gentoo
 * 3) Download and extract the latest archive (stage file) which creates a minimal Gentoo environment to further install from
 * 4) Chroot into this minimal Gentoo environment and install a Linux kernel, core utilities and boot loader
 * 5) Reboot into the freshly installed Gentoo system

A huge advantage of letting the user perform all steps on their own is that the user can now decide how they want to install Gentoo - the options are there, the user needs to make a choice, over and over again. By clearly identifying the options and documenting the possible roads Gentoo hopes that the user is not scared but rather impressed.

Download, burn and boot
In order to boot a medium from which Gentoo can be installed, the first thing to know is for which architecture the installation should be done.

Gentoo supports a number of architectures, namely:

In this handbook, we focus on the architecture.

Download the media
The default installation media that Gentoo Linux uses are the minimal installation CDs, which host a bootable, very small Gentoo Linux environment with the right tools to install Gentoo Linux from. The CD images themselves can be downloaded from one of the many mirrors available.

On those mirrors, the minimal installation CDs can be found as follows:
 * 1) Go to the  directory
 * 2) Select the right architecture, such as
 * 3) Select the  directory
 * 4) Select the  directory

Inside this location, the installation CD file is the file with the suffix. For instance, take a look at the following listing:

In the above example, the file is the minimal installation CD itself. But as can be seen, other related files exist as well:
 * A file which is a text file listing all files available on the installation CD. This file can be useful to verify if particular firmware or drivers are available on the installation CD before downloading it.
 * A file which contains the hash of the ISO file itself, in various hashing formats/algorithms. This file can be used to verify if the downloaded ISO file is corrupt or not.
 * A file which not only contains the hash of the ISO file, like the  file, but also a cryptographic signature of that file. This can be used to both verify if the downloaded ISO file is corrupt or not, as well as verify that the download is indeed provided by the Gentoo Release Engineering team and has not been tampered with.

Ignore the other files available at this location for now - those will come back when the installation has proceeded further. Download the file and, if verification of the download is wanted, download the   file for the ISO file as well. The file does not need to be downloaded as the installation instructions will not refer to this file anymore, and the  file should contain the same information as the  file, except that the latter also contains a signature on top of it.

Verifying the downloaded files
Through the and  files, the validity of the ISO file can be confirmed using the right set of tools. This verification is usually done in two steps:
 * 1) First, the cryptographic signature is validated to make sure that the installation file is provided by the Gentoo Release Engineering team
 * 2) If the cryptographic signature validates, then the checksum is verified to make sure that the downloaded file itself is not corrupted

Microsoft Windows based verification
On a Microsoft Windows system, chances are low that the right set of tools to verify checksums and cryptographic signatures are in place.

To first verify the cryptographic signature, tools such as GPG4Win can be used. After installation, the public keys of the Gentoo Release Engineering team need to be imported. The list of keys is available on the release engineering page. Once imported, the user can then verify the signature of the file.

The checksum itself can be verified using the DeepDigest application, although many others exist as well (see this Wikipedia article for details). Most of the time, these tools will show the user the calculated checksum, and the user is requested to verify this checksum with the value that is inside the file.

Linux based verification
On a Linux system, the most common method for verifying the cryptographic signature is to use the software. With this package installed, the following commands can be used to verify the cryptographic signature of the file.

First, download the right set of keys as made available on the release engineering page:

Next verify the cryptographic signature of the file:

To be absolutely certain that everything is valid, verify the fingerprint shown with the fingerprint on the Gentoo release engineering page.

With the cryptographic signature validated, next verify the checksum to make sure the downloaded ISO file is not corrupted. The file contains multiple hashing algorithms, so one of the methods to validate the right one is to first look at the checksum registered in the  file. For instance, to get the SHA512 checksum:

In the above output, two SHA512 checksums are shown - one for the file and one for its accompanying  file. Only the first checksum is of interest, as it needs to be compared with the calculated SHA512 checksum which can be generated as follows:

As both checksums match, the file is not corrupted and the installation can continue.

Burning
Of course, with just an ISO file downloaded, the Gentoo Linux installation cannot be started. The ISO file needs to be burned on a CD to boot from, and in such a way that its contents is burned on the CD, not just the file itself. Below a few common methods are described - a more elaborate set of instructions can be found in Our FAQ on burning an ISO file.

Burning with Microsoft Windows
On Microsoft Windows, a number of tools exist that support burning ISOs on CDs.


 * With EasyCD Creator, select File, Record CD from CD image. Then change the Files of type to ISO image file. Then locate the ISO file and click Open. After clicking on Start recording the ISO image will be burned correctly onto the CD-R.
 * With Nero Burning ROM, cancel the wizard which automatically pops up and select Burn Image from the File menu. Select the image to burn and click Open. Now hit the Burn button and watch the brand new CD being burnt.

Burning with Linux
On Linux, the ISO file can be burned on a CD using the  command, part of the  package.

For instance, to burn the ISO file on the CD in the device (this is the first CD device on the system - substitute with the right device file if necessary):

Users that prefer a graphical user interface can use K3B, part of the package. In K3B, go to Tools and use Burn CD Image. Then follow the instructions provided by K3B.

Booting the CD
With the CD burned, the installation of Gentoo Linux can now commence. Put the CD in the drive and reboot the system, making sure that the system now boots from the CD.

On most systems, it is possible to change the boot order at boot time once, such as by pressing, or  (Escape) before the system starts booting the operating system. How to achieve this is specific to each system, so consult the system documentation of the computer if uncertain.

Once booted, the installation CD will greet the user with a root prompt, indicating that the system is waiting for further input:

This is the command-line prompt which will be used to install Gentoo Linux from in the next set of sections.