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Release Notes for Debian GNU/Linux 4.0 ("etch"), PowerPC
Chapter 4 - Upgrades from previous releases


4.1 Preparing for the upgrade

We suggest that before upgrading you also read the information in Issues to be aware of for etch, Chapter 5. That chapter covers potential issues not directly related to the upgrade process but which could still be important to know about before you begin.


4.1.1 Back up any data or configuration information

Before upgrading your system, it is strongly recommended that you make a full backup, or at least back up any data or configuration information you can't afford to lose. The upgrade tools and process are quite reliable, but a hardware failure in the middle of an upgrade could result in a severely damaged system.

The main things you'll want to back up are the contents of /etc, /var/lib/dpkg, /var/lib/aptitude/pkgstates and the output of dpkg --get-selections "*" (the quotes are important).

The upgrade process itself does not modify anything in the /home directory. However, some applications (e.g. parts of the Mozilla suite, and the GNOME and KDE desktop environments) are known to overwrite existing user settings with new defaults when a new version of the application is first started by a user. As a precaution, you may want to make a backup of the hidden files and directories ("dotfiles") in users' home directories. This backup may help to restore or recreate the old settings. You may also want to inform users about this.

Any package installation operation must be run with superuser privileges, so either login as root or use su or sudo to gain the necessary access rights.

The upgrade has a few preconditions; you should check them before actually executing the upgrade.


4.1.2 Inform users in advance

It's wise to inform all users in advance of any upgrades you're planning, although users accessing your system via an ssh connection should notice little during the upgrade, and should be able to continue working.

If you wish to take extra precautions, back up or unmount users' partitions (/home) before upgrading.

You will probably have to do a kernel upgrade when upgrading to etch, so a reboot will normally be necessary. Typically, this will be done after the upgrade is finished.


4.1.3 Prepare for recovery

Because of the many changes in the kernel between sarge and etch regarding drivers, hardware discovery and the naming and ordering of device files, there is a real risk that you may experience problems rebooting your system after the upgrade. A lot of known potential issues are documented in this and the next chapters of these Release Notes.

For that reason it makes sense to ensure that you will be able to recover if your system should fail to reboot or, for remotely managed systems, fail to bring up networking.

If you are upgrading remotely via an ssh link it is highly recommended that you take the necessary precautions to be able to access the server through a remote serial terminal. There is a chance that, after upgrading the kernel and rebooting, some devices will be renamed (as described in Device enumeration reordering, Section 4.6.4) and you will have to fix the system configuration through a local console. Also, if the system is rebooted accidentally in the middle of an upgrade there is a chance you will need to recover using a local console.

The most obvious thing to try first is to reboot with your old kernel. However, for various reasons documented elsewhere in this document, this is not guaranteed to work.

If that fails, you will need an alternative way to boot your system so you can access and repair it. One option is to use a special rescue image or a Linux live CD. After booting from that, you should be able to mount your root file system and chroot into it to investigate and fix the problem.

Another option we'd like to recommend is to use the rescue mode of the etch Debian Installer. The advantage of using the installer is that you can choose between its many installation methods for one that best suits your situation. For more information, please consult the section "Recovering a Broken System" in chapter 8 of the Installation Guide and the Debian Installer FAQ.


4.1.3.1 Debug shell during boot using initrd

The initramfs-tools includes a debug shell[6] in the initrds it generates. If for example the initrd is unable to mount your root file system, you will be dropped into this debug shell which has basic commands available to help trace the problem and possibly fix it.

Basic things to check are: presence of correct device files in /dev; what modules are loaded (cat /proc/modules); output of dmesg for errors loading drivers. The output of dmesg will also show what device files have been assigned to which disks; you should check that against the output of echo $ROOT to make sure that the root file system is on the expected device.

If you do manage to fix the problem, typing exit will quit the debug shell and continue the boot process at the point it failed. Of course you will also need to fix the underlying problem and regenerate the initrd so the next boot won't fail again.


4.1.4 Prepare a safe environment for the upgrade

The distribution upgrade should be done either locally from a textmode virtual console (or a directly connected serial terminal), or remotely via an ssh link.

In order to gain extra safety margin when upgrading remotely, we suggest that you run upgrade processes in the virtual console provided by the screen program, which enables safe reconnection and ensures the upgrade process is not interrupted even if the remote connection process fails.

Important! You should not upgrade using telnet, rlogin, rsh, or from an X session managed by xdm, gdm or kdm etc on the machine you are upgrading. That is because each of those services may well be terminated during the upgrade, which can result in an inaccessible system that is only half-upgraded.


4.1.5 Support for 2.2-kernels has been dropped

In case you run a kernel prior to 2.4.1, you need to upgrade to (at least) the 2.4-series before upgrading glibc. This should be done before starting the upgrade. It is recommended that you directly upgrade to the 2.6.8 kernel available in sarge, instead of upgrading to a 2.4 kernel.


4.2 Checking system status

The upgrade process described in this chapter has been designed for upgrades from "pure" sarge systems without third-party packages. In particular, there are known problems with third-party packages which install programs under /usr/X11R6/bin/ causing problems with upgrades due to the X.Org transition (XFree86 to X.Org transition, Section 5.3). For greatest reliability of the upgrade process, you may wish to remove third-party packages from your system before you begin upgrading.

This procedure also assumes your system has been updated to the latest point release of sarge. If you have not done this or are unsure, follow the instructions in Upgrading your sarge system, Section A.1.


4.2.1 Review actions pending in package manager

In some cases, the use of apt-get for installing packages instead of aptitude might make aptitude consider a package as "unused" and schedule it for removal. In general, you should make sure the system is fully up-to-date and "clean" before proceeding with the upgrade.

Because of this you should review if there are any pending actions in the package manager aptitude. If a package is scheduled for removal or update in the package manager, it might negatively impact the upgrade procedure. Note that correcting this is only possible if your sources.list still points to sarge; and not to stable or etch; see Checking your sources list, Section A.2.

To do this, you have to run aptitude's user interface and press 'g' ("Go"). If it shows any actions, you should review them and either fix them or implement the suggested actions. If no actions are suggested you will be presented with a message saying "No packages are scheduled to be installed, removed, or upgraded".


4.2.2 Disabling APT pinning

If you have configured APT to install certain packages from a distribution other than stable (e.g. from testing), you may have to change your APT pinning configuration (stored in /etc/apt/preferences) to allow the upgrade of packages to the versions in the new stable release. Further information on APT pinning can be found in apt_preferences(5).


4.2.3 Checking packages status

Regardless of the method used for upgrading, it is recommended that you check the status of all packages first, and verify that all packages are in an upgradable state. The following command will show any packages which have a status of Half-Installed or Failed-Config, and those with any error status.

     # dpkg --audit

You could also inspect the state of all packages on your system using dselect, aptitude, or with commands such as

     # dpkg -l | pager

or

     # dpkg --get-selections "*" > ~/curr-pkgs.txt

It is desirable to remove any holds before upgrading. If any package that is essential for the upgrade is on hold, the upgrade will fail.

Note that aptitude uses a different method for registering packages that are on hold than apt-get and dselect. You can identify packages on hold for aptitude with

     # aptitude search "~ahold" | grep "^.h"

If you want to check which packages you had on hold for apt-get, you should use

     # dpkg --get-selections | grep hold

If you changed and recompiled a package locally, and didn't rename it or put an epoch in the version, you must put it on hold to prevent it from being upgraded.

The "hold" package state for aptitude can be changed using:

     # aptitude hold package_name

Replace hold with unhold to unset the "hold" state.

If there is anything you need to fix, it is best to make sure your sources.list still refers to sarge as explained in Checking your sources list, Section A.2.


4.2.4 Unofficial sources and backports

If you have any non-Debian packages on your system, you should be aware that these may be removed during the upgrade because of conflicting dependencies. If these packages were installed by adding an extra package archive in your /etc/apt/sources.list, you should check if that archive also offers packages compiled for etch and change the source line accordingly at the same time as your source lines for Debian packages.

Some users may have unofficial backported "newer" versions of packages that are in Debian installed on their sarge system. Such packages are most likely to cause problems during an upgrade as they may result in file conflicts[7]. Section Possible issues during upgrade, Section 4.5.8 has some information on how to deal with file conflicts if they should occur.


4.3 Manually unmarking packages

To prevent aptitude from removing some packages that were pulled in through dependencies, you need to manually unmark them as auto packages. This includes OpenOffice and Vim for desktop installs:

     # aptitude unmarkauto openoffice.org vim

And 2.6 kernel images if you have installed them using a kernel metapackage:

     # aptitude unmarkauto $(dpkg-query -W 'kernel-image-2.6.*' | cut -f1)

Note: You can review which packages are marked as auto in aptitude by running:

     # aptitude search 'i~M <package name>'

4.4 Preparing sources for APT

Before starting the upgrade you must set up apt's configuration file for package lists, /etc/apt/sources.list.

apt will consider all packages that can be found via any "deb" line, and install the package with the highest version number, giving priority to the first mentioned lines (that way, in case of multiple mirror locations, you'd typically first name a local harddisk, then CD-ROMs, and then HTTP/FTP mirrors).

A release can often be referred to by both its codename (e.g. sarge, etch) and by its status name (i.e. oldstable, stable, testing, unstable). Referring to a release by its codename has the advantage that you will never be surprised by a new release and for this reason is the approach taken here. It does of course mean that you will have to watch out for release announcements yourself. If you use the status name instead, you will just see loads of updates for packages available as soon as a release has happened.


4.4.1 Adding APT Internet sources

The default configuration is set up for installation from main Debian Internet servers, but you may wish to modify /etc/apt/sources.list to use other mirrors, preferably a mirror that is network-wise closest to you.

Debian HTTP or FTP mirror addresses can be found at http://www.debian.org/distrib/ftplist (look at the "Full list of mirrors" section). HTTP mirrors are generally speedier than FTP mirrors.

For example, suppose your closest Debian mirror is http://mirrors.kernel.org/debian/. When inspecting that mirror with a web browser or FTP program, you will notice that the main directories are organized like this:

     http://mirrors.kernel.org/debian/dists/etch/main/binary-powerpc/...
     http://mirrors.kernel.org/debian/dists/etch/contrib/binary-powerpc/...

To use this mirror with apt, you add this line to your sources.list file:

     deb http://mirrors.kernel.org/debian etch main contrib

Note that the `dists' is added implicitly, and the arguments after the release name are used to expand the path into multiple directories.

After adding your new sources, disable the previously existing "deb" lines in sources.list by placing a hash sign (#) in front of them.


4.4.2 Adding APT sources for a local mirror

Instead of using HTTP or FTP packages mirrors, you may wish to modify /etc/apt/sources.list to use a mirror on a local disk (possibly mounted over NFS).

For example, your packages mirror may be under /var/ftp/debian/, and have main directories like this:

     /var/ftp/debian/dists/etch/main/binary-powerpc/...
     /var/ftp/debian/dists/etch/contrib/binary-powerpc/...

To use this with apt, add this line to your sources.list file:

     deb file:/var/ftp/debian etch main contrib

Note that the `dists' is added implicitly, and the arguments after the release name are used to expand the path into multiple directories.

After adding your new sources, disable the previously existing "deb" lines in sources.list by placing a hash sign (#) in front of them.


4.4.3 Adding APT source from CD-ROM or DVD

If you want to use CDs only, comment out the existing "deb" lines in /etc/apt/sources.list by placing a hash sign (#) in front of them.

Make sure there is a line in /etc/fstab that enables mounting your CD-ROM drive at the /cdrom mount point (the exact /cdrom mount point is required for apt-cdrom). For example, if /dev/hdc is your CD-ROM drive, /etc/fstab should contain a line like:

     /dev/hdc /cdrom auto defaults,noauto,ro 0 0

Note that there must be no spaces between the words defaults,noauto,ro in the fourth field.

To verify it works, insert a CD and try running

     # mount /cdrom    # this will mount the CD to the mount point
     # ls -alF /cdrom  # this should show the CD's root directory
     # umount /cdrom   # this will unmount the CD

Next, run:

     # apt-cdrom add

for each Debian Binary CD-ROM you have, to add the data about each CD to APT's database.


4.5 Upgrading packages

The recommended way to upgrade from previous Debian GNU/Linux releases is to use the package management tool aptitude. This program makes safer decisions about package installations than running apt-get directly.

Don't forget to mount all needed partitions (notably the root and /usr partitions) read-write, with a command like:

     # mount -o remount,rw /mountpoint

Next you should double-check that the APT source entries (in /etc/apt/sources.list) refer either to "etch" or to "stable". There should not be any sources entries pointing to sarge. Note: source lines for a CD-ROM will often refer to "unstable"; although this may be confusing, you should not change it.


4.5.1 Recording the session

It is strongly recommended that you use the /usr/bin/script program to record a transcript of the upgrade session. Then if a problem occurs, you will have a log of what happened, and if needed, can provide exact information in a bug report. To start the recording, type:

     # script -t 2>~/upgrade-etch.time -a ~/upgrade-etch.script

or similar. Do not put the typescript file in a temporary directory such as /tmp or /var/tmp (files in those directories may be deleted during the upgrade or during any restart).

The typescript will also allow you to review information that has scrolled off-screen. Just switch to VT2 (using Alt-F2) and, after logging in, use less -R ~root/upgrade-etch.script to view the file.

After you have completed the upgrade, you can stop script by typing exit at the prompt.

If you have used the -t switch for script you can use the scriptreplay program to replay the whole session:

     # scriptreplay ~/upgrade-etch.time ~/upgrade-etch.script

4.5.2 Updating the package list

First the list of available packages for the new release needs to be fetched. This is done by executing:

     # aptitude update

Running this the first time new sources are updated will print out some warnings related to the availability of the sources. These warnings are harmless and will not appear if you rerun the command again.


4.5.3 Make sure you have sufficient space for the upgrade

You have to make sure before upgrading your system that you have sufficient hard disk space when you start the full system upgrade described in Upgrading the rest of the system, Section 4.5.6. First, any package needed for installation that is fetched from the network is stored in /var/cache/apt/archives (and the partial/ subdirectory, during download), so you must make sure you have enough space on the file system partition that holds /var/ to temporarily download the packages that will be installed in your system. After the download, you will probably need more space in other file system partitions in order to both install upgraded packages (which might contain bigger binaries or more data) and new packages that will be pulled in for the upgrade. If your system does not have sufficient space you might end up with an incomplete upgrade that might be difficult to recover from.

Both aptitude and apt will show you detailed information of the disk space needed for the installation. Before executing the upgrade, you can see this estimate by running:

     # aptitude -y -s -f --with-recommends dist-upgrade
     [ ... ]
     XXX upgraded, XXX newly installed, XXX to remove and XXX not upgraded.
     Need to get xx.xMB/yyyMB of archives. After unpacking AAAMB will be used.
     Would download/install/remove packages.

[8]

If you do not have enough space for the upgrade, make sure you free up space beforehand. You can:

Note that in order to safely remove packages, it is advisable to switch your sources.list back to sarge as described in Checking your sources list, Section A.2.


4.5.4 Minimal system upgrade

Because of certain necessary package conflicts between sarge and etch, running aptitude dist-upgrade directly will often remove large numbers of packages that you will want to keep. We therefore recommend a two-part upgrade process, first a minimal upgrade to overcome these conflicts, then a full dist-upgrade.

First, run:

     # aptitude upgrade

This has the effect of upgrading those packages which can be upgraded without requiring any other packages to be removed or installed.

Follow the minimal upgrade with:

     # aptitude install initrd-tools

This step will automatically upgrade libc6 and locales and will pull in SELinux support libraries (libselinux1). At this point, some running services will be restarted, including xdm, gdm and kdm. As a consequence, local X11 sessions will be disconnected.

The next step will vary depending on the set of packages that you have installed. These release notes give general advice about which method should be used, but if in doubt, it is recommended that you examine the package removals proposed by each method before proceeding.

Some common packages that are expected to be removed include base-config, hotplug, xlibs, netkit-inetd, python2.3, xfree86-common, and xserver-common. For a more complete list of packages obsoleted in etch, see Obsolete packages, Section 4.10.


4.5.4.1 Upgrading a desktop system

This upgrade path has been verified to work on systems with the sarge desktop task installed. It is probably the method that will give the best results on systems with the desktop task installed, or with the gnome or kde packages installed.

It is probably not the correct method to use if you do not already have the libfam0c102 and xlibmesa-glu packages installed:

     # dpkg -l libfam0c102 | grep ^ii
     # dpkg -l xlibmesa-glu | grep ^ii

If you do have a full desktop system installed, run:

     # aptitude install libfam0 xlibmesa-glu

4.5.4.2 Upgrading a system with some X packages installed

Systems with some X packages installed, but not the full desktop task, require a different method. This method applies in general to systems with xfree86-common installed, including some server systems which have tasksel server tasks installed as some of these tasks include graphical management tools. It is likely the correct method to use on systems which run X, but do not have the full desktop task installed.

     # dpkg -l xfree86-common | grep ^ii

First, check whether you have the libfam0c102 and xlibmesa-glu packages installed.

     # dpkg -l libfam0c102 | grep ^ii
     # dpkg -l xlibmesa-glu | grep ^ii

If you do not have libfam0c102 installed, do not include libfam0 in the following commandline. If you do not have xlibmesa-glu installed, do not include it in the following commandline. [9]

     # aptitude install x11-common libfam0 xlibmesa-glu

Note that installing libfam0 will also install the File Alteration Monitor (fam) as well as the RPC portmapper (portmap) if not already available in your system. Both packages will enable a new network service in the system although they can both be configured to be bound to the (internal) loopback network device.


4.5.4.3 Upgrading a system with no X support installed

On a system with no X, no additional aptitude install command should be required, and you can move on to the next step.


4.5.5 Upgrading the kernel

The udev version in etch does not support kernel versions earlier than 2.6.15 (which includes sarge 2.6.8 kernels), and the udev version in sarge will not work properly with the latest kernels. In addition, installing the etch version of udev will force the removal of hotplug, used by Linux 2.4 kernels.

As a consequence, the previous kernel package will probably not boot properly after this upgrade. Similarly, there is a time window during the upgrade in which udev has been upgraded but the latest kernel has not been installed. If the system were to be rebooted at this point, in the middle of the upgrade, it might not be bootable because of drivers not being properly detected and loaded. (See Prepare a safe environment for the upgrade, Section 4.1.4 for recommendations on preparing for this possibility if you are upgrading remotely.)

Unless your system has the desktop task installed, or other packages that would cause an unacceptable number of package removals, it is therefore recommended that you upgrade the kernel on its own at this point.

To proceed with this kernel upgrade, run:

     # aptitude install linux-image-2.6-flavor

See Installing the kernel metapackage, Section 4.6.1 for help in determining which flavor of kernel package you should install.

In the desktop case, it is unfortunately not possible to ensure the new kernel package is installed immediately after the new udev is installed, so there is a window of unknown length when your system will have no kernel installed with full hotplug support. See Upgrading your kernel and related packages, Section 4.6 for information on configuring your system to not depend on hotplug for booting.


4.5.6 Upgrading the rest of the system

You are now ready to continue with the main part of the upgrade. Execute:

     # aptitude dist-upgrade

This will perform a complete upgrade of the system, i.e. install the newest available versions of all packages, and resolve all possible dependency changes between packages in different releases. If necessary, it will install some new packages (usually new library versions, or renamed packages), and remove any conflicting obsoleted packages.

When upgrading from a set of CD-ROMs, you will be asked to insert specific CDs at several points during the upgrade. You might have to insert the same CD multiple times; this is due to inter-related packages that have been spread out over the CDs.

New versions of currently installed packages that cannot be upgraded without changing the install status of another package will be left at their current version (displayed as "held back"). This can be resolved by either using aptitude to choose these packages for installation or by trying aptitude -f install package.


4.5.7 Getting package signatures

After the upgrade, with the new version of apt you can now update your package information, which will include the new package signature checking mechanism:

     # aptitude update

The upgrade will have already retrieved and enabled the signing keys for Debian's package archives. If you add other (unofficial) package sources, apt will print warnings related to its inability to confirm that packages downloaded from them are legitimate and have not been tampered with. For more information please see Package management, Section 2.2.1.

You will notice that, since you are using the new version of apt, it will download package differences files (pdiff) instead of the full package index list. For more information on this feature please read Slower updates of APT package index files, Section 5.1.4.


4.5.8 Possible issues during upgrade

If an operation using aptitude, apt-get, or dpkg fails with the error

     E: Dynamic MMap ran out of room

the default cache space is insufficient. You can solve this by either removing or commenting lines you don't need in /etc/apt/sources.list or by increasing the cache size. The cache size can be increased by setting APT::Cache-Limit in /etc/apt/apt.conf. The following command will set it to a value that should be sufficient for the upgrade:

     # echo 'APT::Cache-Limit "12500000";' >> /etc/apt/apt.conf

This assumes that you do not yet have this variable set in that file.

Sometimes it's necessary to enable the APT::Force-LoopBreak option in APT to be able to temporarily remove an essential package due to a Conflicts/Pre-Depends loop. aptitude will alert you of this and abort the upgrade. You can work around that by specifying -o APT::Force-LoopBreak=1 option on aptitude command line.

It is possible that a system's dependency structure can be so corrupt as to require manual intervention. Usually this means using aptitude or

     # dpkg --remove package_name

to eliminate some of the offending packages, or

     # aptitude -f install
     # dpkg --configure --pending

In extreme cases you might have to force re-installation with a command like

     # dpkg --install /path/to/package_name.deb

File conflicts should not occur if you upgrade from a "pure" sarge system, but can occur if you have unofficial backports installed. A file conflict will result in an error like:

     Unpacking <package-foo> (from <package-foo-file>) ...
     dpkg: error processing <package-foo> (--install):
      trying to overwrite `<some-file-name>',
      which is also in package <package-bar>
     dpkg-deb: subprocess paste killed by signal (Broken pipe)
      Errors were encountered while processing:
      <package-foo>

You can try to solve a file conflict by forcibly removing the package mentioned on the last line of the error message:

     # dpkg -r --force-depends package_name

After fixing things up, you should be able to resume the upgrade by repeating the previously described aptitude commands.

During the upgrade, you will be asked questions regarding the configuration or re-configuration of several packages. When you are asked if any file in the /etc/init.d or /etc/terminfo directories, or the /etc/manpath.config file should be replaced by the package maintainer's version, it's usually necessary to answer `yes' to ensure system consistency. You can always revert to the old versions, since they will be saved with a .dpkg-old extension.

If you're not sure what to do, write down the name of the package or file and sort things out at a later time. You can search in the typescript file to review the information that was on the screen during the upgrade.


4.6 Upgrading your kernel and related packages

This section explains how to upgrade your kernel and identifies potential issues related to this upgrade. You can either install one of the linux-image-* packages provided by Debian, or compile a customized kernel from source.

Note that a lot of information in this section is based on the assumption that you will be using one of the modular Debian kernels, together with initramfs-tools and udev. If you choose to use a custom kernel that does not require an initrd or if you use a different initrd generator, some of the information may not be relevant for you.

Note also that if udev is not installed on your system, it is still possible to use hotplug for hardware discovery.

If you are currently using a 2.4 kernel, you should also read Upgrading to a 2.6 kernel, Section 5.2 carefully.


4.6.1 Installing the kernel metapackage

When you dist-upgrade from sarge to etch, it is strongly recommended that you install a new linux-image-2.6-* metapackage. This package may be installed automatically by the dist-upgrade process. You can verify this by running:

     # dpkg -l "linux-image*" | grep ^ii

If you do not see any output, then you will need to install a new linux-image package by hand. To see a list of available linux-image-2.6 metapackages, run:

     # apt-cache search linux-image-2.6- | grep -v transition

If you are unsure about which package to select, run uname -r and look for a package with a similar name. For example, if you see '2.4.27-3-686', it is recommended that you install linux-image-2.6-686. You may also use apt-cache to see a long description of each package in order to help choose the best one available. For example:

     # apt-cache show linux-image-2.6-686

You should then use aptitude install to install it. Once this new kernel is installed you should reboot at the next available opportunity to get the benefits provided by the new kernel version.

For the more adventurous there is an easy way to compile your own custom kernel on Debian GNU/Linux. Install the kernel-package tool and read the documentation in /usr/share/doc/kernel-package.


4.6.2 Upgrading from a 2.6 kernel

If you are currently running a 2.6 series kernel from sarge this upgrade will take place automatically after you do a full upgrade of the system packages (as described in Upgrading packages, Section 4.5).

If possible, it is to your advantage to upgrade the kernel package separately from the main dist-upgrade to reduce the chances of a temporarily non-bootable system. See Upgrading the kernel, Section 4.5.5 for a description of this process. Note that this should only be done after the minimal upgrade process described in Minimal system upgrade, Section 4.5.4.

You can also take this step if you are using your own custom kernel and want to use the kernel available in etch. If your kernel version is not supported by udev then it is recommended that you upgrade after the minimal upgrade. If your version is supported by udev you can safely wait until after the full system upgrade.


4.6.3 Upgrading from a 2.4 kernel

If you have a 2.4 kernel installed, and your system relies on hotplug for its hardware detection you should first upgrade to a 2.6 series kernel from sarge before attempting the upgrade. Make sure that the 2.6 series kernel boots your system and all your hardware is properly detected before you perform the upgrade. The hotplug package is removed from the system (in favor of udev) when you do a full system upgrade. If you do not do the kernel upgrade before this your system might not boot up properly from this point on. Once you have done an upgrade to a 2.6 series kernel in sarge you can do a kernel upgrade as described in Upgrading from a 2.6 kernel, Section 4.6.2.

If your system does not rely on hotplug[10] you can delay the kernel upgrade to after you have done a full system upgrade, as described in Upgrading the rest of the system, Section 4.5.6. Once your system has been upgraded you can then do the following (changing the kernel package name to the one most suited to your system by substituting <flavor>):

     # aptitude install linux-image-2.6-<flavor>

4.6.4 Device enumeration reordering

etch features a more robust mechanism for hardware discovery than previous releases. However, this may cause changes in the order devices are discovered on your system, affecting the order in which device names are assigned. For example, if you have two network adapters that are associated with two different drivers, the devices eth0 and eth1 refer to may be swapped. Please note that the new mechanism means that if you e.g. exchange ethernet adapters in a running etch system, the new adapter will also get a new interface name.

For network devices, you can avoid this reordering by using udev rules, more specifically, through the definitions at /etc/udev/rules.d/z25_persistent-net.rules[11]. Alternatively you can use the ifrename utility to bind physical devices to specific names at boot time. See ifrename(8) and iftab(5) for more information. The two alternatives (udev and ifrename) should not be used at the same time.

For storage devices, you can avoid this reordering by using initramfs-tools and configuring it to load storage device driver modules in the same order they are currently loaded. To do this, identify the order the storage modules on your system were loaded by looking at the output of lsmod. lsmod lists modules in the reverse order that they were loaded in, i.e., the first module in the list was the last one loaded. Note that this will only work for devices which the kernel enumerates in a stable order (like PCI devices).

However, removing and reloading modules after initial boot will affect this order. Also, your kernel may have some drivers linked statically, and these names will not appear in the output of lsmod. You may be able to decipher these driver names and load order from looking at /var/log/kern.log, or the output of dmesg.

Add these module names to /etc/initramfs-tools/modules in the order they should be loaded at boot time. Some module names may have changed between sarge and etch. For example, sym53c8xx_2 has become sym53c8xx.

You will then need to regenerate your initramfs image(s) by executing update-initramfs -u -k all.

Once you are running a etch kernel and udev, you may reconfigure your system to access disks by an alias that is not dependent upon driver load order. These aliases reside in the /dev/disk/ hierarchy.


4.6.5 Boot timing issues

If an initrd created with initramfs-tools is used to boot the system, in some cases the creation of device files by udev can happen too late for the boot scripts to act on.

The usual symptoms are that the boot will fail because the root file system cannot be mounted and you are dropped into a debug shell, but that when you check afterwards, all devices that are needed are present in /dev. This has been observed in cases where the root file system is on a USB disk or on RAID, especially if lilo is used.

A workaround for this issue is to use the boot parameter rootdelay=9. The value for the timeout (in seconds) may need to be adjusted.


4.6.6 PCILynx FireWire driver is broken

The PCILynx driver is horribly broken and might result in driver crashes on PowerPC. We encourage users who need FireWire to avail themselves of one of the cheap OHCI1394 cards and blacklist PCILynx driver.


4.7 Things to do before rebooting

When aptitude dist-upgrade has finished, the "formal" upgrade is complete, but there are some other things that should be taken care of before the next reboot.


4.7.1 Converting from devfs

Debian kernels no longer include support for devfs, so devfs users will need to convert their systems manually before booting an etch kernel.

If you see the string 'devfs' in /proc/mounts, you are most likely using devfs. Any configuration files that reference devfs-style names will need to be adjusted to use udev-style names. Files that are likely to refer to devfs-style device names include /etc/fstab, /etc/lilo.conf, /boot/grub/menu.lst, and /etc/inittab.

More information about potential issues is available in bug report #341152.


4.7.2 Upgrading mdadm

mdadm now needs a configuration file to assemble MD arrays (RAID) from the initial ramdisk and during the system initialisation sequence. Please make sure to read and act upon the instructions in /usr/share/doc/mdadm/README.upgrading-2.5.3.gz after the package has been upgraded and before you reboot. The latest version of this file is available at http://svn.debian.org/wsvn/pkg-mdadm/mdadm/trunk/debian/README.upgrading-2.5.3?op=file; please consult it in case of problems.


4.8 Preparing for the next release

After the upgrade there are several things you can do to prepare for the next release.


4.9 Deprecated packages

With the release of Lenny a bigger number of server packages will be deprecated, thus updating to newer versions of those now will save you from trouble when updating to Lenny.

This includes the following packages:


4.10 Obsolete packages

Introducing several thousand new packages, etch also retires and omits more than two thousand old packages that were in sarge. It provides no upgrade path for these obsolete packages. While nothing prevents you from continuing to use an obsolete package where desired, the Debian project will usually discontinue security support for it a year after etch's release[12], and will not normally provide other support in the meantime. Replacing them with available alternatives, if any, is recommended.

There are many reasons why packages might have been removed from the distribution: they are no longer maintained upstream; there is no longer a Debian Developer interested in maintaining the packages; the functionality they provide has been superseded by different software (or a new version); or they are no longer considered suitable for etch due to bugs in them. In the latter case, packages might still be present in the "unstable" distribution.

Detecting which packages in an updated system are "obsolete" is easy since the package management front-ends will mark them as such. If you are using aptitude, you will see a listing of these packages in the "Obsolete and Locally Created Packages" entry. dselect provides a similar section but the listing it presents might differ. Also, if you have used aptitude to manually install packages in sarge it will have kept track of those packages you manually installed and will be able to mark as obsolete those packages pulled in by dependencies alone which are no longer needed if a package has been removed. Also, aptitude, unlike deborphan will not mark as obsolete packages that you manually installed, as opposed to those that were automatically installed through dependencies.

There are additional tools you can use to find obsolete packages such as deborphan, debfoster or cruft. deborphan is highly recommended, although it will (in default mode) only report obsolete libraries: packages in the "libs" or "oldlibs" sections that are not used by any other packages. Do not blindly remove the packages these tools present, especially if you are using aggressive non-default options that are prone to produce false positives. It is highly recommended that you manually review the packages suggested for removal (i.e. their contents, size and description) before you remove them.

The Debian Bug Tracking System often provides additional information on why the package was removed. You should review both the archived bug reports for the package itself and the archived bug reports for the ftp.debian.org pseudo-package.


4.10.1 Dummy packages

Some packages from sarge have been split into several packages in etch, often to improve system maintainability. To ease the upgrade path in such cases, etch often provides "dummy" packages: empty packages that have the same name as the old package in sarge with dependencies that cause the new packages to be installed. These "dummy" packages are considered obsolete packages after the upgrade and can be safely removed.

Most (but not all) dummy packages' descriptions indicate their purpose. Package descriptions for dummy packages are not uniform, however, so you might also find deborphan with the --guess options useful to detect them in your system. Note that some dummy packages are not intended to be removed after an upgrade but are, instead, used to keep track of the current available version of a program over time.


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Release Notes for Debian GNU/Linux 4.0 ("etch"), PowerPC

$Id: release-notes.en.sgml,v 1.312 2007-08-16 22:24:38 jseidel Exp $

Josip Rodin, Bob Hilliard, Adam Di Carlo, Anne Bezemer, Rob Bradford, Frans Pop (current), Andreas Barth (current), Javier Fernández-Sanguino Peña (current), Steve Langasek (current)
debian-doc@lists.debian.org