Getting Perl modules into Debian
Debians Perl team from an end-user perspective

Tim Retout

11th September 2010 HantsLUG @ IBM Hursley

pkg-perl for users

What is the Debian Perl team?
Maintain almost 1700 Perl packages within Debian Both ocial Debian Developers and sponsees Around 70-80 committers,1 but most activity from a small core team Also indirectly contributes most of the Perl packages in Debians derivatives (e.g. Ubuntu).
http://www.ohloh.net/p/pkg-perl
Tim Retout pkg-perl for users

Using Perl on Debian

How do you install Perl modules? apt-get install libfoo-perl Backports for older releases CPAN for unpackaged modules CPAN (the tool) is congured to play nicely with Debian packages, but does not install packages when satisfying dependencies.
When a module isnt packaged
If the Perl module you need is not available, you have several options:
Install it with CPAN, and handle future upgrades yourself. File an RFP (Request for package) bug in Debian.2 Build yourself a private Debian package with dh-make-perl, and handle future upgrades yourself. Get involved and contribute it back to Debian!
Getting involved is easier than you think.
http://pkg-perl.alioth.debian.org/howto/RFP.html

Getting involved - tools

The Perl team uses tools to speed up packaging. alioth.debian.org for team management SVN for most packages, but a few are stored in git http://bugs.debian.org/ Package Entropy Tracker (PET) IRC (#debian-perl on OFTC) Two mailing lists - one for discussion, one to receive automated messages http://pkg-perl.alioth.debian.org/ links to all of these.
Getting involved - joining the team
Create an alioth account Apply to join the pkg-perl group on alioth Introduce yourself on the debian-perl mailing list Optionally use IRC for realtime communication http://wiki.debian.org/Teams/DebianPerlGroup/Welcome
Creating a package - dh-make-perl
dh-make-perl can jump-start creating a new Perl package. apt-get install dh-make-perl and read the man page. Run dh-make-perl --cpan Module::Name. Add --pkg-perl if you are packaging for the team. Then run debuild and hack until it builds. If you dont want to contribute it to Debian, you could stop here.
Creating a package - svn-buildpackage
Once you have an initial package, you can upload to SVN. pkg-perl uses a fairly complex SVN layout.3 Use svn-inject to inject new packages svn-buildpackage for building svn-upgrade for upstream upgrades Set the suite to UNRELEASED in debian/changelog for now. Commits are logged to IRC.
http://pkg-perl.alioth.debian.org/subversion.html
Creating a package - cowbuilder
One of the more tricky parts of packaging is getting the build dependencies correct. cowbuilder is a tool for building packages in a clean chroot: sudo apt-get install cowbuilder sudo cowbuilder --create sudo cowbuilder --build libfoo-perl 1.0-1.dsc Can also integrate it into svn-buildpackage. Check the test suite gets run!
Creating a package - lintian
We want Debian packages to be of high quality. lintian is a tool that can check for common problems. sudo apt-get install lintian lintian -iI --pedantic --color=auto libfoo-perl 1.0-1 amd64.changes Can also integrate it with debuild/cowbuilder
Creating a package - getting feedback
Once you think your package is ready for review, mark it as such: dch -r (or s/UNRELEASED/unstable/ in debian/changelog) svn commit -m dch -r; ready for review The package status will be changed automatically in PET.
Creating a package - what next?
You are likely to get feedback via IRC or email. Sometimes TODO lists are left for you in debian/changelog by the reviewer, with the suite set back to UNRELEASED. Once the reviewer is happy, they will upload the package and tag the release in SVN.

Questions?

<diocles@debian.org>

Debian developers are also involved in a number of other projects; some specic to Debian, others involving some or all of the Linux community. Some examples include:
The Linux Standard Base (http://www.linuxbase.org/) (LSB) is a project aimed at standardizing the basic GNU/Linux system, which will enable third-party software and hardware developers to easily design programs and device drivers for Linux-in-general, rather than for a specic GNU/Linux distribution. The Filesystem Hierarchy Standard (http://www.pathname.com/fhs/) (FHS) is an effort to standardize the layout of the Linux le system. The FHS will allow software developers to concentrate their efforts on designing programs, without having to worry about how the package will be installed in different GNU/Linux distributions.
Debian Jr. (http://www.debian.org/devel/debian-jr/) is an internal project, aimed at making sure Debian has something to offer to our youngest users.
For more general information about Debian, see the Debian FAQ (http://www.debian.org/doc/FAQ/).

1.2. What is GNU/Linux?

Linux is an operating system: a series of programs that let you interact with your computer and run other programs. An operating system consists of various fundamental programs which are needed by your computer so that it can communicate and receive instructions from users; read and write data to hard disks, tapes, and printers; control the use of memory; and run other software. The most important part of an operating system is the kernel. In a GNU/Linux system, Linux is the kernel component. The rest of the system consists of other programs, many of which were written by or for the GNU Project. Because the Linux kernel alone does not form a working operating system, we prefer to use the term GNU/Linux to refer to systems that many people casually refer to as Linux. Linux is modelled on the Unix operating system. From the start, Linux was designed to be a multitasking, multi-user system. These facts are enough to make Linux different from other well-known operating systems. However, Linux is even more different than you might imagine. In contrast to other operating systems, nobody owns Linux. Much of its development is done by unpaid volunteers. Development of what later became GNU/Linux began in 1984, when the Free Software Foundation (http://www.fsf.org/) began development of a free Unix-like operating system called GNU. The GNU Project (http://www.gnu.org/) has developed a comprehensive set of free software tools for use with Unix and Unix-like operating systems such as Linux. These tools enable users to perform tasks ranging from the mundane (such as copying or removing les from the system) to the arcane (such as writing and compiling programs or doing sophisticated editing in a variety of document formats). While many groups and individuals have contributed to Linux, the largest single contributor is still the Free Software Foundation, which created not only most of the tools used in Linux, but also the philosophy and the community that made Linux possible. The Linux kernel (http://www.kernel.org/) rst appeared in 1991, when a Finnish computing science student named Linus Torvalds announced an early version of a replacement kernel for Minix to the Usenet newsgroup comp.os.minix. See Linux Internationals Linux History Page (http://www.cs.cmu.edu/~awb/linux.history.html). Linus Torvalds continues to coordinate the work of several hundred developers with the help of a number of subsystem maintainers. There is an ofcial website (http://www.kernel.org/) for the Linux kernel. More information about the linux-kernel mailing list can be found on the linux-kernel mailing list FAQ (http://www.tux.org/lkml/). Linux users have immense freedom of choice in their software. For example, Linux users can choose from a dozen different command line shells and several graphical desktops. This selection is often bewildering to users of other operating systems, who are not used to thinking of the command line or desktop as something that they can change. Linux is also less likely to crash, better able to run more than one program at the same time, and more secure than many operating systems. With these advantages, Linux is the fastest growing operating system in the server market. More recently, Linux has begun to be popular among home and business users as well.

1.3. What is Debian GNU/Linux?
The combination of Debians philosophy and methodology and the GNU tools, the Linux kernel, and other important free software, form a unique software distribution called Debian GNU/Linux. This distribution is made up of a large number of software packages. Each package in the distribution contains executables, scripts, documentation, and conguration information, and has a maintainer who is primarily responsible for keeping the package up-to-date, tracking bug reports, and communicating with the upstream author(s) of the packaged software. Our extremely large user base, combined with our bug tracking system ensures that problems are found and xed quickly. Debians attention to detail allows us to produce a high-quality, stable, and scalable distribution. Installations can be easily congured to serve many roles, from stripped-down rewalls to desktop scientic workstations to high-end network servers. Debian is especially popular among advanced users because of its technical excellence and its deep commitment to the needs and expectations of the Linux community. Debian also introduced many features to Linux that are now commonplace. For example, Debian was the rst Linux distribution to include a package management system for easy installation and removal of software. It was also the rst Linux distribution that could be upgraded without requiring reinstallation. Debian continues to be a leader in Linux development. Its development process is an example of just how well the Open Source development model can work even for very complex tasks such as building and maintaining a complete operating system. The feature that most distinguishes Debian from other Linux distributions is its package management system. These tools give the administrator of a Debian system complete control over the packages installed on that system, including the ability to install a single package or automatically update the entire operating system. Individual packages can also be protected from being updated. You can even tell the package management system about software you have compiled yourself and what dependencies it fullls. To protect your system against Trojan horses and other malevolent software, Debians servers verify that uploaded packages come from their registered Debian maintainers. Debian packagers also take great care to congure their packages in a secure manner. When security problems in shipped packages do appear, xes are usually available very quickly. With Debians simple update options, security xes can be downloaded and installed automatically across the Internet. The primary, and best, method of getting support for your Debian GNU/Linux system and communicating with Debian Developers is through the many mailing lists maintained by the Debian Project (there are more than 215 at this writing). The easiest way to subscribe to one or more of these lists is visit Debians mailing list subscription page (http://www.debian.org/MailingLists/subscribe) and ll out the form youll nd there.

4.3. Preparing Files for USB Memory Stick Booting
There are two installation methods possible when booting from USB stick. The rst is to install
Chapter 4. Obtaining System Installation Media completely from the network. The second is to also copy a CD image onto the USB stick and use that as a source for packages, possibly in combination with a mirror. This second method is the more common. For the rst installation method youll need to download an installer image from the netboot directory (at the location mentioned in Section 4.2.1) and use the exible way explained below to copy the les to the USB stick. Installation images for the second installation method can be found in the hd-media directory and either the easy way or the exible way can be used to copy the image to the USB stick. For this installation method you will also need to download a CD image. The installation image and the CD image must be based on the same release of debian-installer. If they do not match you are likely to get errors1 during the installation. To prepare the USB stick, you will need a system where GNU/Linux is already running and where USB is supported. With current GNU/Linux systems the USB stick should be automatically recognized when you insert it. If it is not you should check that the usb-storage kernel module is loaded. When the USB stick is inserted, it will be mapped to a device named /dev/sdX, where the X is a letter in the range a-z. You should be able to see to which device the USB stick was mapped by running the command dmesg after inserting it. To write to your stick, you may have to turn off its write protection switch.

Warning

The procedures described in this section will destroy anything already on the device! Make very sure that you use the correct device name for your USB stick. If you use the wrong device the result could be that all information on for example a hard disk could be lost.
Note that the USB stick should be at least 256 MB in size (smaller setups are possible if you follow Section 4.3.2).
4.3.1. Copying the les the easy way
There is an all-in-one le hd-media/boot.img.gz which contains all the installer les (including the kernel) as well as syslinux and its conguration le. Note that, although convenient, this method does have one major disadvantage: the logical size of the device will be limited to 256 MB, even if the capacity of the USB stick is larger. You will need to repartition the USB stick and create new le systems to get its full capacity back if you ever want to use it for some different purpose. A second disadvantage is that you cannot copy a full CD image onto the USB stick, but only the smaller businesscard or netinst CD images. To use this image simply extract it directly to your USB stick:

Note: For a Debian GNU/Linux server we recommend tftpd-hpa. Its written by the same author as the syslinux bootloader and is therefore least likely to cause issues. A good alternative is atftpd.
4.5.1. Setting up a DHCP server
One free software DHCP server is ISC dhcpd. For Debian GNU/Linux, the dhcp3-server package is recommended. Here is a sample conguration le for it (see /etc/dhcp3/dhcpd.conf):
option domain-name "example.com"; option domain-name-servers ns1.example.com; option subnet-mask 255.255.255.0; default-lease-time 600; max-lease-time 7200; server-name "servername"; subnet 192.168.1.0 netmask 255.255.255.0 { range 192.168.1.200 192.168.1.253; option routers 192.168.1.1; } host clientname { filename "/tftpboot.img"; server-name "servername"; next-server servername; hardware ethernet 01:23:45:67:89:AB; fixed-address 192.168.1.90; }
In this example, there is one server servername which performs all of the work of DHCP server, TFTP server, and network gateway. You will almost certainly need to change the domain-name options, as well as the server name and client hardware address. The filename option should be the name of the le which will be retrieved via TFTP.
Chapter 4. Obtaining System Installation Media After you have edited the dhcpd conguration le, restart it with /etc/init.d/dhcpd3-server restart.
4.5.1.1. Enabling PXE Booting in the DHCP conguration
Here is another example for a dhcp.conf using the Pre-boot Execution Environment (PXE) method of TFTP.
option domain-name "example.com"; default-lease-time 600; max-lease-time 7200; allow booting; allow bootp; # The next paragraph needs to be modified to fit your case subnet 192.168.1.0 netmask 255.255.255.0 { range 192.168.1.200 192.168.1.253; option broadcast-address 192.168.1.255; # the gateway address which can be different # (access to the internet for instance) option routers 192.168.1.1; # indicate the dns you want to use option domain-name-servers 192.168.1.3; } group { next-server 192.168.1.3; host tftpclient { # tftp client hardware address hardware ethernet 00:10:DC:27:6C:15; filename "/pxelinux.0"; } }
Note that for PXE booting, the client lename pxelinux.0 is a boot loader, not a kernel image (see Section 4.5.4 below).
4.5.2. Setting up a BOOTP server
There are two BOOTP servers available for GNU/Linux. The rst is CMU bootpd. The other is actually a DHCP server: ISC dhcpd. In Debian GNU/Linux these are contained in the bootp and dhcp3-server packages respectively. To use CMU bootpd, you must rst uncomment (or add) the relevant line in /etc/inetd.conf. On Debian GNU/Linux, you can run update-inetd --enable bootps, then /etc/init.d/inetd reload to do so. Just in case your BOOTP server does not run Debian, the line in question should look like:

/home / /var swap

This example shows two IDE harddrives divided into several partitions; the rst disk has some free space. Each partition line consists of the partition number, its type, size, optional ags, le system, and mountpoint (if any). Note: this particular setup cannot be created using guided partitioning but it does show possible variation that can be achieved using manual partitioning. This concludes the guided partitioning. If you are satised with the generated partition table, you can choose Finish partitioning and write changes to disk from the menu to implement the new partition
Chapter 6. Using the Debian Installer table (as described at the end of this section). If you are not happy, you can choose to Undo changes to partitions and run guided partitioning again, or modify the proposed changes as described below for manual partitioning.
6.3.2.3. Manual Partitioning
A similar screen to the one shown just above will be displayed if you choose manual partitioning except that your existing partition table will be shown and without the mount points. How to manually set up your partition table and the usage of partitions by your new Debian system will be covered in the remainder of this section. If you select a pristine disk which has neither partitions nor free space on it, you will be asked if a new partition table should be created (this is needed so you can create new partitions). After this, a new line entitled FREE SPACE should appear in the table under the selected disk. If you select some free space, you will have the opportunity to create a new partition. You will have to answer a quick series of questions about its size, type (primary or logical), and location (beginning or end of the free space). After this, you will be presented with a detailed overview of your new partition. The main setting is Use as:, which determines if the partition will have a le system on it, or be used for swap, software RAID, LVM, an encrypted le system, or not be used at all. Other settings include mountpoint, mount options, and bootable ag; which settings are shown depends on how the partition is to be used. If you dont like the preselected defaults, feel free to change them to your liking. E.g. by selecting the option Use as:, you can choose a different lesystem for this partition, including options to use the partition for swap, software RAID, LVM, or not use it at all. Another nice feature is the ability to copy data from an existing partition onto this one. When you are satised with your new partition, select Done setting up the partition and you will return to partmans main screen. If you decide you want to change something about your partition, simply select the partition, which will bring you to the partition conguration menu. This is the same screen as is used when creating a new partition, so you can change the same settings. One thing that may not be very obvious at a rst glance is that you can resize the partition by selecting the item displaying the size of the partition. Filesystems known to work are at least fat16, fat32, ext2, ext3 and swap. This menu also allows you to delete a partition. Be sure to create at least two partitions: one for the root lesystem (which must be mounted as /) and one for swap. If you forget to mount the root lesystem, partman wont let you continue until you correct this issue. Capabilities of partman can be extended with installer modules, but are dependent on your systems architecture. So if you cant see all promised goodies, check if you have loaded all required modules (e.g. partman-ext3, partman-xfs, or partman-lvm). After you are satised with partitioning, select Finish partitioning and write changes to disk from the partitioning menu. You will be presented with a summary of changes made to the disks and asked to conrm that the lesystems should be created as requested.

Before you input any passphrases, you should have made sure that your keyboard is congured correctly and generates the expected characters. If you are unsure, you can switch to the second virtual console and type some text at the prompt. This ensures that you wont be surprised later, e.g. by trying to input a passphrase using a qwerty keyboard layout when you used an azerty layout during the installation. This situation can have several causes. Maybe you switched to another keyboard layout during the installation, or the selected keyboard layout might not have been set up yet when entering the passphrase for the root le system.
If you selected to use methods other than a passphrase to create encryption keys, they will be generated now. Because the kernel may not have gathered a sufcient amount of entropy at this early stage of the installation, the process may take a long time. You can help speed up the process by generating entropy: e.g. by pressing random keys, or by switching to the shell on the second virtual console and generating some network and disk trafc (downloading some les, feeding big les into /dev/null, etc.). This will be repeated for each partition to be encrypted. After returning to the main partitioning menu, you will see all encrypted volumes as additional partitions which can be congured in the same way as ordinary partitions. The following example shows two different volumes. The rst one is encrypted via dm-crypt, the second one via loop-AES.
Encrypted volume (sda2_crypt) - 115.1 GB Linux device-mapper #1 115.1 GB F ext3 Loopback (loop0) - 515.2 MB AES256 keyfile #1 515.2 MB F ext3
Now is the time to assign mount points to the volumes and optionally change the le system types if the defaults do not suit you. Pay attention to the identiers in parentheses (sda2_crypt and loop0 in this case) and the mount points you assigned to each encrypted volume. You will need this information later when booting the new system. The differences between the ordinary boot process and the boot process with encryption involved will be covered later in Section 7.2. Once you are satised with the partitioning scheme, continue with the installation.
6.3.3. Installing the Base System
Although this stage is the least problematic, it consumes a signicant fraction of the install because it downloads, veries and unpacks the whole base system. If you have a slow computer or network connection, this could take some time. During installation of the base system, package unpacking and setup messages are redirected to tty4. You can access this terminal by pressing Left Alt-F4; get back to the main installer process with Left Alt-F1. The unpack/setup messages generated during this phase are also saved in /var/log/syslog. You can check them there if the installation is performed over a serial console.

The easiest way to create a preconguration le is to use the example le linked in Section B.4 as basis and work from there. An alternative method is to do a manual installation and then, after rebooting, use the debconf-getselections from the debconf-utils package to dump both the debconf database and the installers cdebconf database to a single le:
$ debconf-get-selections --installer > file $ debconf-get-selections >> file
However, a le generated in this manner will have some items that should not be preseeded, and the example le is a better starting place for most users.
Note: This method relies on the fact that, at the end of the installation, the installers cdebconf database is saved to the installed system in /var/log/installer/cdebconf. However, because the database may contain sensitive information, by default the les are only readable by root. The directory /var/log/installer and all les in it will be deleted from your system if you purge the package installation-report.
To check possible values for questions, you can use nano to examine the les in
/var/lib/cdebconf while an installation is in progress. View templates.dat for the raw templates and questions.dat for the current values and for the values assigned to variables.
To check if the format of your preconguration le is valid before performing an install, you can use the command debconf-set-selections -c preseed.cfg.
B.4. Contents of the preconguration le (for squeeze)
The conguration fragments used in this appendix are also available as an example preconguration le from http://d-i.alioth.debian.org/manual/example-preseed.txt. Note that this example is based on an installation for the Intel x86 architecture. If you are installing a different architecture, some of the examples (like keyboard selection and bootloader installation) may not be relevant and will need to be replaced by debconf settings appropriate for your architecture.

B.4.1. Localization

Setting localization values will only work if you are using initrd preseeding. With all other methods the preconguration le will only be loaded after these questions have been asked. The locale can be used to specify both language and country and can be any combination of a language supported by debian-installer and a recognized country. If the combination does not form a valid locale, the installer will automatically select a locale that is valid for the selected language. To specify the locale as a boot parameter, use locale=en_US. Although this method is very easy to use, it does not allow preseeding of all possible combinations of language, country and locale2. So alternatively the values can be preseeded individually. Language and country can also be specied as boot parameters.

#d-i # # # # # # # # #

# For additional information see the file partman-auto-raid-recipe.txt # included in the debian-installer package or available from D-I source # repository. # This makes partman automatically partition without confirmation. d-i partman-md/confirm boolean true d-i partman-partitioning/confirm_write_new_label boolean true d-i partman/choose_partition select finish d-i partman/confirm boolean true d-i partman/confirm_nooverwrite boolean true
B.4.6.3. Controlling how partitions are mounted
Normally, lesystems are mounted using a universally unique identier (UUID) as a key; this allows them to be mounted properly even if their device name changes. UUIDs are long and difcult to read, so, if you prefer, the installer can mount lesystems based on the traditional device names, or based on a label you assign. If you ask the installer to mount by label, any lesystems without a label will be mounted using a UUID instead. Devices with stable names, such as LVM logical volumes, will continue to use their traditional names rather than UUIDs.
Traditional device names may change based on the order in which the kernel discovers devices at boot, which may cause the wrong lesystem to be mounted. Similarly, labels are likely to clash if you plug in a new disk or a USB drive, and if that happens your systems behaviour when started will be random.
# The default is to mount by UUID, but you can also choose "traditional" to # use traditional device names, or "label" to try filesystem labels before # falling back to UUIDs. #d-i partman/mount_style select uuid
B.4.7. Base system installation
There is actually not very much that can be preseeded for this stage of the installation. The only questions asked concern the installation of the kernel.
# Configure APT to not install recommended packages by default. Use of this # option can result in an incomplete system and should only be used by very # experienced users. #d-i base-installer/install-recommends boolean false # Select the initramfs generator used to generate the initrd for 2.6 kernels. #d-i base-installer/kernel/linux/initramfs-generators string yaird # The kernel image (meta) package to be installed; "none" can be used if no # kernel is to be installed. #d-i base-installer/kernel/image string linux-image-2.6-486

B.4.8. Account setup

The password for the root account and name and password for a rst regular users account can be preseeded. For the passwords you can use either clear text values or MD5 hashes.
Be aware that preseeding passwords is not completely secure as everyone with access to the preconguration le will have the knowledge of these passwords. Using MD5 hashes is considered slightly better in terms of security but it might also give a false sense of security as access to a MD5 hash allows for brute force attacks.
# Skip creation of a root account (normal user account will be able to # use sudo). #d-i passwd/root-login boolean false # Alternatively, to skip creation of a normal user account. #d-i passwd/make-user boolean false # Root password, either in clear text #d-i passwd/root-password password r00tme #d-i passwd/root-password-again password r00tme # or encrypted using an MD5 hash. #d-i passwd/root-password-crypted password [MD5 hash] # To create a normal user account. #d-i passwd/user-fullname string Debian User #d-i passwd/username string debian

C.5.1. Partitioning for Intel x86
If you have an existing other operating system such as DOS or Windows and you want to preserve that operating system while installing Debian, you may need to resize its partition to free up space for the Debian installation. The installer supports resizing of both FAT and NTFS lesystems; when you get to the installers partitioning step, select the option Manual and then simply select an existing partition and change its size. The PC BIOS generally adds additional constraints for disk partitioning. There is a limit to how many primary and logical partitions a drive can contain. Additionally, with pre 199498 BIOSes, there are limits to where on the drive the BIOS can boot from. More information can be found in the Linux Partition HOWTO (http://www.tldp.org/HOWTO/Partition/) and the Phoenix BIOS FAQ (http://www.phoenix.com/en/Customer+Services/BIOS/BIOS+FAQ/default.htm), but this section will include a brief overview to help you plan most situations. Primary partitions are the original partitioning scheme for PC disks. However, there can only be four of them. To get past this limitation, extended and logical partitions were invented. By setting one of your primary partitions as an extended partition, you can subdivide all the space allocated to that partition into logical partitions. You can create up to 60 logical partitions per extended partition; however, you can only have one extended partition per drive. Linux limits the partitions per drive to 15 partitions for SCSI disks (3 usable primary partitions, 12 logical partitions), and 63 partitions on an IDE drive (3 usable primary partitions, 60 logical partitions). However the normal Debian GNU/Linux system provides only 20 devices for partitions, so you may not install on partitions higher than 20 unless you rst manually create devices for those partitions. If you have a large IDE disk, and are using neither LBA addressing, nor overlay drivers (sometimes provided by hard disk manufacturers), then the boot partition (the partition containing your kernel image) must be placed within the rst 1024 cylinders of your hard drive (usually around 524 megabytes, without BIOS translation). This restriction doesnt apply if you have a BIOS newer than around 199598 (depending on the manufacturer) that supports the Enhanced Disk Drive Support Specication. Both Lilo, the Linux loader, and Debians alternative mbr must use the BIOS to read the kernel from the disk into RAM. If the BIOS int 0x13 large disk access extensions are found to be present, they will be utilized. Otherwise, the legacy disk access interface is used as a fall-back, and it cannot be used to address any location on the disk higher than the 1023rd cylinder. Once Linux is booted, no matter what BIOS your computer has, these restrictions no longer apply, since Linux does not use the BIOS for disk access. If you have a large disk, you might have to use cylinder translation techniques, which you can set from your BIOS setup program, such as LBA (Logical Block Addressing) or CHS translation mode (Large). More information about issues with large disks can be found in the Large Disk HOWTO (http://www.tldp.org/HOWTO/Large-Disk-HOWTO.html). If you are using a cylinder translation scheme, and the BIOS does not support the large disk access extensions, then your boot partition has to t within the translated representation of the 1024th cylinder. The recommended way of accomplishing this is to create a small (2550MB should sufce) partition at the beginning of the disk to be used as the boot partition, and then create whatever other partitions you wish to have, in the remaining area. This boot partition must be mounted on /boot, since that is the directory where the Linux kernel(s) will be stored. This conguration will work on any system, regardless of whether LBA or large disk CHS translation is used, and regardless of whether your BIOS supports the large disk access extensions.

Appendix D. Random Bits

D.1. Linux Devices
In Linux various special les can be found under the directory /dev. These les are called device les and behave unlike ordinary les. The most common types of device les are for block devices and character devices. These les are an interface to the actual driver (part of the Linux kernel) which in turn accesses the hardware. Another, less common, type of device le is the named pipe. The most important device les are listed in the tables below.

fd0 fd1

First Floppy Drive Second Floppy Drive
hda hdb hdc hdd hda1 hdd15
IDE Hard disk / CD-ROM on the rst IDE port (Master) IDE Hard disk / CD-ROM on the rst IDE port (Slave) IDE Hard disk / CD-ROM on the second IDE port (Master) IDE Hard disk / CD-ROM on the second IDE port (Slave) First partition of the rst IDE hard disk Fifteenth partition of the fourth IDE hard disk

sda sdb sdc sda1 sdd10

SCSI Hard disk with lowest SCSI ID (e.g. 0) SCSI Hard disk with next higher SCSI ID (e.g. 1) SCSI Hard disk with next higher SCSI ID (e.g. 2) First partition of the rst SCSI hard disk Tenth partition of the fourth SCSI hard disk

sr0 sr1

SCSI CD-ROM with the lowest SCSI ID SCSI CD-ROM with the next higher SCSI ID
ttyS0 ttyS1 psaux gpmdata
Serial port 0, COM1 under MS-DOS Serial port 1, COM2 under MS-DOS PS/2 mouse device Pseudo device, repeater data from GPM (mouse) daemon
Symbolic link to the CD-ROM drive
Symbolic link to the mouse device le

null zero

Anything written to this device will disappear One can endlessly read zeros out of this device
D.1.1. Setting Up Your Mouse
The mouse can be used in both the Linux console (with gpm) and the X window environment. Normally, this is a simple matter of installing gpm and the X server itself. Both should be congured to use /dev/input/mice as the mouse device. The correct mouse protocol is named exps2 in gpm, and ExplorerPS/2 in X. The respective conguration les are /etc/gpm.conf and /etc/X11/xorg.conf. Certain kernel modules must be loaded in order for your mouse to work. In most cases the correct modules are autodetected, but not always for old-style serial and bus mice1, which are quite rare except on very old computers. Summary of Linux kernel modules needed for different mouse types: Module psmouse usbhid sermouse logibm inport Description PS/2 mice (should be autodetected) USB mice (should be autodetected) Most serial mice Bus mouse connected to Logitech adapter card Bus mouse connected to ATI or Microsoft InPort card
To load a mouse driver module, you can use the modconf command (from the package with the same name) and look in the category kernel/drivers/input/mouse.

3. Congure the network

Auto-congure network with DHCP: No IP address: 192.168.0.1 Point-to-point address: 192.168.0.2 Name server addresses: you can enter the same addresses used on source (see /etc/resolv.conf)
D.5. Installing Debian GNU/Linux using PPP over Ethernet (PPPoE)
In some countries PPP over Ethernet (PPPoE) is a common protocol for broadband (ADSL or cable) connections to an Internet Service Provider. Setting up a network connection using PPPoE is not supported by default in the installer, but can be made to work very simply. This section explains how. The PPPoE connection set up during the installation will also be available after the reboot into the installed system (see Chapter 7). To have the option of setting up and using PPPoE during the installation, you will need to install using one of the CD-ROM/DVD images that are available. It is not supported for other installation methods (e.g. netboot). Installing over PPPoE is mostly the same as any other installation. The following steps explain the differences.
Boot the installer with the boot parameter modules=ppp-udeb3. This will ensure the component responsible for the setup of PPPoE (ppp-udeb) will be loaded and run automatically. Follow the regular initial steps of the installation (language, country and keyboard selection; the loading of additional installer components4). The next step is the detection of network hardware, in order to identify any Ethernet cards present in the system. After this the actual setup of PPPoE is started. The installer will probe all the detected Ethernet interfaces in an attempt to nd a PPPoE concentrator (a type of server which handles PPPoE connections). It is possible that the concentrator will not to be found at the rst attempt. This can happen occasionally on slow or loaded networks or with faulty servers. In most cases a second attempt to detect the concentrator will be successful; to retry, select Congure and start a PPPoE connection from the main menu of the installer.
After a concentrator is found, the user will be prompted to type the login information (the PPPoE username and password). At this point the installer will use the provided information to establish the PPPoE connection. If the correct information was provided, the PPPoE connection should be congured and the installer should be able to use it to connect to the Internet and retrieve packages over it (if needed). If the login information is not correct or some error appears, the installer will stop, but the conguration can be attempted again by selecting the menu entry Congure and start a PPPoE connection.

Yoyodyne, Inc., hereby disclaims all copyright interest in the program Gnomovision (which makes passes at compilers) written by James Hacker.
signature of Ty Coon, 1 April 1989 Ty Coon, President of Vice
This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License.