The Debian Administrator's Handbook

The fundamental difference between 32 and 64 bit systems is the size of memory addresses. In theory, a 32 bit system can not work with more than 4 GB of RAM (2³² bytes). In practice, it is possible to work around this limitation by using the 686-bigmem kernel variant, so long as the processor handles the PAE (Physical Address Extension) functionality. Using it does have a notable influence on system performance, however. This is why it is useful to use the 64 bit mode on a server with a large amount of RAM.

For an office computer (where a few percent difference in performance is negligible), you must keep in mind that some proprietary programs are not available in 64 bit versions (such as Skype and the plugin for handling Java applets in web browsers, for example). It is technically possible to make them work on 64 bit systems, but you have to install the 32 bit versions with all the necessary libraries, and often to use setarch or linux32 (in the util-linux package) to trick applications regarding the nature of the system. This is very demanding for a relatively small gain.

IN PRACTICE Installation alongside an existing Windows system

If the computer is already running Windows, it is not necessary to delete the system in order to install Debian. You can have both systems at once, each installed on a separate disk or partition, and choose which to start when booting the computer. This configuration is often called “dual boot”, and the Debian installation system can set it up. This is done during the hard drive partitioning stage of installation and while setting up the bootloader (see the sidebars in those sections).

If you already have a working Windows system, you can even do without the recovery CD-ROM; Debian offers a Windows program that will download a light Debian installer and set it up on the hard disk. You then only need to reboot the computer and choose between normal Windows boot or booting the installation program. You can also find it on a dedicated website with a rather explicit name...

→ http://ftp.debian.org/debian/tools/win32-loader/stable/

→ http://www.goodbye-microsoft.com/

BACK TO BASICS Boot loader

The bootloader is a low-level program that is responsible for booting the Linux kernel just after the BIOS passes off its control. To handle this task, it must be able to locate the Linux kernel to boot on the disk. On i386/amd64 architectures, the two most used programs to perform this task are LILO, the older of the two, and GRUB, a more modern challenger. Isolinux and Syslinux are alternatives frequently used to boot from removable media.

Each menu entry hides a specific boot command line, which can be configured as needed by pressing the TAB key before validating the entry and booting. The “Help” menu entry displays the old command line interface, where the F1 to F10 keys display different help screens detailing the various options available at the prompt. You will rarely need to use this option except in very specific cases.

The “expert” mode (accessible in the “Advanced Options” menu) details all possible options in the process of installation, and allows navigation between the various steps without them happening automatically in sequence. Be careful, this very verbose mode can be confusing due to the multitude of configuration choices that it offers.

Figure 4.1. Boot screen

Once booted, the installation program guides you step by step throughout the process. This section presents each of these steps in detail. Here we follow the process of an installation from a Multi-Arch DVD-ROM; other types of installlations, (netinst or businesscard) may be slightly different. We will also address installation in graphical mode, but this differs from “classic” installation only in appearance.

4.2.2. Selecting the language

The installation program begins in English, but the first step allows the user to choose the language that will be used in the rest of the process. Choosing French, for example, will provide an installation entirely translated into French (and a system configured in French as a result). This choice is also used to define more relevant default choices in subsequent stages (notably the keyboard layout).

BACK TO BASICS Navigating with the keyboard

Some steps in the installation process require you to enter information. These screens have several areas that may “have focus” (text entry area, checkboxes, list of choices, OK and Cancel buttons), and the TAB key allows you to move from one to another.

In graphical mode, you can use the mouse.

Figure 4.2. Selecting the language

4.2.3. Selecting the country