Gentoo Handbook

1. Gentoo and Upgrades

Philosophy

Here in Gentoo land, the concept of upgrading is quite different compared to the rest of the Linux world. You probably already know that we never got in touch with the "classic" way of upgrading software: waiting for a new release, downloading it, burning, putting it in the cdrom drive and then following the upgrade instructions.

You know (being a Gentoo user after all) that this process is extremely frustrating for power users that want to live on the bleeding edge. Even power users from other distributions probably share the same feelings, given the popularity and spread of tools like apt or apt-rpm which make it possible to have quick and frequent updates. However, no distibution is more suited than Gentoo to satisfy these kind of demanding users. From the beginning, Gentoo was designed around the concept of fast, incremental updates.

Ideally, you install once and never bother with releases: just follow the instructions in A Portage Introduction in the Gentoo Handbook that explain how to keep your system up to date. While that's the way things usually go, sometimes changes are made to the core system which require updates to be done manually.

Releases and Profiles

A recurring question about the Gentoo release process is: "Why roll out new releases frequently, if they are not intended to let users update software?". There are various reasons:

• A new release means new LiveCDs with bugfixes and more features.
• A new release provides an updated set of GRP packages, so that users that choose "the fast way" to install (stage3 + precompiled packages) end up with a system that is not outdated.
• Finally, a new release may, from time to time, implement some features that are incompatible with previous releases.

When a release includes new incompatible features, or provides a set of core packages and settings that deeply modify the behavior of the system, we say that it provides a new profile.

A profile is a set of configuration files, stored in a subdirectory of /usr/portage/profiles, that describe things such as the ebuilds that are considered system packages, the default USE flags, the default mapping for virtual packages, and the architecture on which the system is running.

The profile in use is determined by the symbolic link /etc/make.profile, which points to a subdirectory of /usr/portage/profiles which holds the profile files. For instance, the default x86 2005.0 profile can be found at /usr/portage/profiles/default-linux/x86/2005.0. The files in the parent directories are part of the profile as well (and are therefore shared by different subprofiles). This is why we call these cascaded profiles.

Profiles obsoleted by new ones are kept in /usr/portage/profiles along with the current ones, but they are marked as deprecated. When that happens a file named deprecated is put in the profile directory. The content of this file is the name of the profile that should be "upgraded to"; portage uses this information to automatically warn you when you should update to a new profile.

There are various reasons that a new profile may be created: the release of new versions of core packages (such as baselayout, gcc, or glibc) that are incompatible with previous versions, a change in the default USE flags or in the virtual mappings, or maybe a change in system-wide settings (such as defining udev to be the default manager for /dev instead of devfs).

2. Keeping Up With New Releases

Releases Without Profile Changes

If a new Gentoo release is announced that does not include a new profile then you can safely pretend that it never happened :).

If you update your installed packages as explained in the Gentoo Handbook, then your system will be exactly the same as one that has been installed using the new release.

Releases With Profile Changes

If a release (such as 2005.0) introduces a new profile, you have the choice to migrate to the new profile.

Naturally, you are not forced to do so, and you can continue to use the old profile and just update your packages as explained in the Gentoo Handbook.

However, Gentoo strongly recommends updating your profile if it becomes deprecated. When this happens, it means that Gentoo developers no longer plan on supporting it. Using the table below, you can quickly check to see what profiles are currently supported.

If you decide to migrate to the new profile, then you will have to manually perform the update. The way you update may vary significantly from release to release; it depends on how deep the modifications introduced in the new profile are.

In the simplest case you only have to change the /etc/make.profile symlink, in the worst case you may have to recompile your system from scratch while doing a neat voodoo dance. Migration is usually covered in the release notes. You can also find instructions at the end of this guide.

Supported Profile

The following profiles are officially supported by Gentoo developers:

3. Profile Updating Instructions

Updating to 2005.0

With the introduction of 2005.0, several architectures have decided to define additional profiles. Make sure you read the description of said profiles before you decide to migrate to one of them. Most architectures now also default to the 2.6 kernel tree where 2.4 was chosen previously.

Some architectures require a bit more actions to be completed in order to convert from one profile to another. If that is the case, the step-by-step guides are linked from the table.

To switch to the selected profile, point the /etc/make.profile symlink to the new location. Make sure your Portage is updated before you change your profile!

# rm /etc/make.profile
# ln -s ../usr/portage/profiles/<selected profile> /etc/make.profile

If you are running a Linux 2.4-based system but want to migrate to a 2.6-based kernel, make sure you read our Gentoo Linux 2.6 Migration Guide.

Updating to 2004.3

With the introduction of the 2004.3 profiles, users are not going to see huge modifications of their systems (see below for details). However, Gentoo developers decided to push out this new profile and to deprecate quite a few of the old ones to speed up the adoption of stacked profiles, that is, the profiles that follow the new layout of the /usr/portage/profiles directory, for instance /usr/portage/profiles/default-linux/x86/2004.3 (supported by Portage 2.0.51 or later).

To switch to the 2004.3 profile, point the /etc/make.profile symlink to the new location:

Warning: Don't forget to upgrade Portage before you change your profile!!!

substitute <arch> with your arch
# rm /etc/make.profile
# ln -s ../usr/portage/profiles/default-linux/<arch>/2004.3 /etc/make.profile

All archs - As said above, there are no big changes introduced in this profile. However, it should be noted that sys-apps/slocate and net-misc/dhcpcd are no longer considered system packages. This means that if you run emerge --depclean, Portage will try to remove them from your system. If you need any of those packages, add them to /var/lib/portage/world after the profile switch, or manually emerge them.

ppc - sys-fs/udev is now the default instead of sys-fs/devfs for newly installed machines. This has no effect on already installed machines, though.

Updating to 2004.2

To switch to the 2004.2 profile, point the /etc/make.profile symlink to the new location:

Warning: Don't forget to upgrade Portage before you change your profile!!!

substitute <arch> with your arch
# rm /etc/make.profile
# ln -s ../usr/portage/profiles/default-linux/<arch>/2004.2 /etc/make.profile

x86 - This profile changes the default X11 implementation from x11-base/xfree to x11-base/xorg-x11. This change only touches the default value, and is only relevant for those who have not installed an X server yet. If you already have one installed, then it will not affect you at all; you are free to switch from one X server to the other exactly as before.

amd64 - There are no fundamental changes from previous profiles, no specific action needs to be performed.

Updating to 2004.0

To switch to the 2004.0 profile, point the /etc/make.profile symlink to the new location:

substitute <arch> with your arch
# rm /etc/make.profile
# ln -s ../usr/portage/profiles/default-linux/<arch>/2004.0 /etc/make.profile

All archs - There are no fundamental changes from previous profiles, no specific action needs to be performed.

Updating From Profiles Older Than 1.4 to 1.4

Please report your idea; disagreeing without providing us with constructive feedback doesn't help the situation. Documentation is made for the community, so community feedback is well appreciated.

However, you must know that most decisions made while developing documentation are based on a consensus-model. It is impossible to write/structure documentation in such a way that everybody is happy with it. You must be able to accept a "No" with the reason that we believe the current implementation benefits most people.

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