GLEP 72: Architecture stability status file

Abstract

This GLEP provides specifications for a new file in the profiles base directory, arches.desc. Its intent is to allow more fine-grained repoman check control, and in particular to help moving architectures from stable to testing while keeping the testing dependency tree consistent, or moving architectures from testing to stable while easily preparing a consistent stable dependency tree.

arches.desc specifies whether an architecture, as opposed to a profile, is to be considered stable. It does not replace profiles.desc, but supplements it; profiles.desc still describes the profiles of each architecture.

We use the term architecture here in the colloquial sense, as also used by the Package Manager Specification in section 4.4.1 (describing profiles.desc), and corresponding in the terminology of GLEP 53 to a "keyword" (which, however, even if more precise is not consistently used in practice).

Motivation

At the moment we have several cases where repoman finds its limits:

1. An architecture loses its stable status (imagine c128), but the architecture team doesn't want to drop all the stable keywords since they are useful for stage building. Since the stable keywords on c128 are only an arch-team-internal thing, everyone is allowed to drop the latest stable version of a package, and it's the arch team's responsibility to keep their "unofficial stable tree" straight. This is how at the time of the writing of this GLEP s390, sh, and m68k are handled.

   Right now this means that we have to set all profiles of this arch to profile status exp in profiles.desc, otherwise repoman throws errors about a broken stable dependency tree. If we do that, repoman does however also not check ~c128 consistency, meaning that the ~c128 dependency tree will soon be broken as well due to negligence. Given arches.conf as described below, one could set the architecture c128 to "transitional" status and keep stable profiles. This results in stable keywords being ignored, but consistency of the ~c128 dependency tree is still enforced.

2. An architecture prepares for becoming a stable architecture (think arm64). So, first the ~arm64 dependency tree should be fine, and then stable keywords can be added. However, to avoid repoman errors as long as the stable dependency tree is not complete yet, the profiles need to be set to dev/exp, and again this brings the danger of the ~arm64 dependency tree getting inadvertently broken. Again the combination of setting the architecture to "transitional" in arches.desc and profiles to stable helps.

Finally, at the moment the "semi-official" algorithm to figure out if an architecture is stable in the colloquial sense (e.g., requires stabilization requests) is to check if the architecture has any stable profile. This makes non-stable arches which want to keep a consistent dependency tree (think mips) impossible. Reading the architecture status from arches.desc instead solves this problem.

Specifications for profiles/arches.desc

# Example arches.desc file
amd64   stable
x86     stable        # not for long

sparc   transitional
m68k    testing

Backwards Compatibility

Essentially two cases need to be discussed. Here "old system" designates a Gentoo installation where package manager and/or utilities do not provide arches.desc support yet, "new system" an installation where they do.

Copyright

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