Handbook:Parts/Installation/Media/fr

Pré-requis pour les matériels
Avant de commencer, nous allons dresser la liste des exigences concernant le matériel pour réussir l'installation de Gentoo sur un système.

CD d'installation minimal
The Gentoo minimal installation CD is a bootable CD which contains a self-sustained Gentoo environment. It allows the user to boot Linux from the CD. During the boot process the hardware is detected and the appropriate drivers are loaded. The CD is maintained by Gentoo developers and allows anyone to install Gentoo if an active Internet connection is available.

The Minimal Installation CD is called.

The occasional Gentoo LiveDVD
Occasionally, a special DVD is crafted by the Gentoo Ten project which can be used to install Gentoo. The instructions further down this chapter target the Minimal Installation CD so might be a bit different. However, the LiveDVD (or any other bootable Linux environment) supports getting a root prompt by just invoking  or   on a terminal.

What are stages then?
A stage3 tarball is an archive containing a minimal Gentoo environment, suitable to continue the Gentoo installation using the instructions in this manual. Previously, the Gentoo Handbook described the installation using one of three stage tarballs. While Gentoo still offers stage1 and stage2 tarballs, the official installation method uses the stage3 tarball. If you are interested in performing a Gentoo installation using a stage1 or stage2 tarball, please read the Gentoo FAQ on How do I Install Gentoo Using a Stage1 or Stage2 Tarball?

Stage3 tarballs can be downloaded from on any of the official Gentoo mirrors and are not provided by the installation CD.

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 site. Once imported, the user can then verify the signature of the file.

The checksum itself can be verified using the Hashcalc application, although many others exist as well. 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 site:

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 site.

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 interested, 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 content 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.

Extra hardware configuration
When the Installation CD boots, it tries to detect all the hardware devices and loads the appropriate kernel modules to support the hardware. In the vast majority of cases, it does a very good job. However, in some cases it may not auto-load the kernel modules needed by the system. If the PCI auto-detection missed some of the system's hardware, the appropriate kernel modules have to be loaded manually.

In the next example the 8139too module (which supports certain kinds of network interfaces) is loaded:

Optional: User accounts
If other people need access to the installation environment, or there is need to run commands as a non-root user on the installation CD (such as to chat using  without root privileges for security reasons), then an additional user account needs to be created and the root password set to a strong password.

To change the root password, use the passwd utility:

To create a user account, first enter their credentials, followed by the account's password. The  and   commands are used for these tasks.

In the next example, a user called john is created:

To switch from the (current) root user to the newly created user account, use the  command:

Optional: Viewing documentation while installing
To view the Gentoo handbook during the installation, first create a user account as described above. Then press +  to go to a new terminal.

During the installation, the  command can be used to browse the Gentoo handbook - of course only from the moment that the Internet connection is working.

To go back to the original terminal, press +.

Optional: Starting the SSH daemon
To allow other users to access the system during the installation (perhaps to support during an installation, or even do it remotely), a user account needs to be created (as was documented earlier on) and the SSH daemon needs to be started.

To fire up the SSH daemon, execute the following command:

To be able to use sshd, the network needs to function properly. Continue with the chapter on Configuring the network.