Most ebuilds specify a KEYWORDS variable. This variable is used to indicate the suitability and stability of both the package and the ebuild on each given arch (sparc, ppc, x86-obsd, ...).

A sample KEYWORDS entry might look like:

KEYWORDS="-ia64 ~mips ~ppc sparc x86 ~ppc-macos"

The different levels of keyword are:

arch (x86, ppc-macos)
Both the package version and the ebuild are widely tested, known to work and not have any serious issues on the indicated platform.
~arch (~x86, ~ppc-macos)
The package version and the ebuild are believed to work and do not have any known serious bugs, but more testing is required before the package version is considered suitable for arch.
No keyword
If a package has no keyword for a given arch, it means it is not known whether the package will work, or that insufficient testing has occurred for ~arch.
-arch (-x86, -ppc-macos)
The package version will not work on the arch. This could be caused by badly written code (for example, non-64-bit or endian clean code), relying upon particular hardware (for example, a BIOS querying tool would not work on non-BIOS architectures) or binary only packages.

The -* keyword is special. It is used to indicate package versions which are not worth trying to test on unlisted archs. For example, a binary-only package which is only supported upstream on ppc and x86 might use:

KEYWORDS="-* ppc x86"

This is different in implication from "ppc x86" — the former implies that it will not work on other archs, whereas the latter implies that it has not been tested.

Do not use the * or ~* special keywords in ebuilds.

Equal Visibility Requirement

An ebuild must not depend upon any package that is of a lower keyword level than itself. For example, if foo-1.2 depends upon bar-1.2, and bar-1.2 is ~x86, then foo-1.2 must not be marked stable on x86 unless bar-1.2 is also stabilised.

You may assume that if a user accepts ~arch for a given arch then they also accept arch.

For optional dependencies, all possible dependencies must satisfy the above. Note that certain USE flags can be forcibly disabled on a per-profile basis — talk to the arch teams if you require this. For either-or dependencies, at least one of the options must be of equal or better visibility than the package in question.

Hard Masks

The package.mask file can be used to 'hard mask' individual or groups of ebuilds. This should be used for testing ebuilds or beta releases of software, and may also be used if a package has serious compatibility problems. Packages which are not hard masked must not have a dependency upon hard masked packages.

The only time it is acceptable for a user to see the Possibly a DEPEND problem error message is if they have manually changed visibility levels for a package (for example, through /etc/portage/) and have missed a dependency. You should never commit a change which could cause this error to appear on a user system.

Keywording New Packages

Do not assume that your package works on all architectures. Do not assume that user submitted ebuilds will have correct KEYWORDS — chances are they just copied from somewhere else. Do not assume that upstream's 'supported architectures' list is correct. Do not assume that because your code is written in Perl / Python / Java / whatever that it will run on other archs (there is at least one case of a vim script which only worked on x86).

Note that most (non-x86) archs expect you to be on the arch team and bugzilla alias if you are committing packages with keywords for that arch, and may have additional requirements of which you should be aware (on mips, for example, there are multiple ABIs and byte orders to consider — a package working on your o32 box may not work on o64 or n32). Contact the individual arch teams for details.

It's important to note that alternative arches (like alpha, ia64, s390, sh, sparc, hppa, ppc*) are mainly undermanned arches, some of them are slow, they have more basic problems and have a small userbase. Just file bugs for these architectures when a package is going to be a dependency of a package already keyworded.

Do not commit straight to arch.

Keywording on Upgrades

When upgrading, drop all existing keywords from arch to ~arch, and leave any existing ~arch keywords intact. This must be done even if you think you're just making a trivial fix — there have been several examples of the stable tree getting broken this way.

Sometimes you may need to remove a keyword because of new unresolved dependencies. If you do this, you must file a bug notifying the relevant arch teams.

This also applies to revision bumps, not just to upstream version changes.

Moving from ~arch to arch

Moving a package from ~arch to arch is done only by the relevant arch teams. If you have access to non-x86 hardware but are not on the arch teams, you may wish to make individual arrangements — the arch teams are happy for help, so long as they know what is going on. Please note that x86 is now no longer an exception and stabilisation must be done through the x86 arch team unless you have individual arrangements — see GLEP 40 for further details.

For a package to move to stable, the following guidelines must be met:

For security fixes, the "reasonable amount of time" guideline may be relaxed. See the Vulnerability Treatment Policy

Simultaneous stabilization on all architectures

If you maintain an architecture-independent package (data files, icons, pure Perl,...) then you may request that your package be stabilized on all arches at once. To do this — when you are filing the stabilization bug — please add the keyword ALLARCHES in addition to STABLEREQ and CC the arches that you would like to stabilize.

The arch teams, when encountering the ALLARCHES keyword, should perform their usual set of tests on a single convenient architecture. Then, if everything works, stabilize not only the arch that was used during testing, but also all of the other arches in CC on the bug. Afterwards, the CC field can be cleared and the bug closed if appropriate.

Removing Package Versions

When removing ebuild, ensure that you do not remove the most recent version at any given keyword level on any profile. The aim here is:

If you would like a particular package version moved to stable on certain archs so that you can tidy up, file a bug.