Bug 10888

I propose we add a section to the manual along the lines of:

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Releases and the Stable Release Process

The Yocto Project deliveres releases on a six month cadence with releases roughly in April and October. There is never a perfect cadance but this timescale has been found to mean we release (and hence have a strong QA cycle) regularly enough that the project quality is maintained but not so often users are overwhelemed with new releases, its a predictable cycle which can be relied upon and it avoids as many major holidays in various geos as we can.

Each release is given a codename which is used to indentify it in the repositories. The idea is that branches of metadata with the same codename are likely to work together. The reason a codename is used is that version numbers often conflict with a given layer's or company's own versioning scheme and the codenames are chosen to be fairly identifiable. The releases are given a nominal release version too but the codename is used in repositories for this reason. Information about the releases and codenames can be found on https://wiki.yoctoproject.org/wiki/Releases

After being released, the release enters the stable release process. A stable release maintainer is appointed for the release and this person then looks after their given stable release and people can nominate patches to be backported. Only things which have first been fixed on master (the current indevelopment branch) can be considered for backporting to the stable release. Our policy is to only consider backporting bug fixes and fixes for security issues, not features. This means generic recipe version upgrades are unlikely to be accepted, unless there is a strong reason like the version upgrade is the upstream preferred approach to security fixes and features are not backported.

The stable releases are periodically released as point releases (e.g. 2.2.1, the first point release of 2.2), this indicate point where we go through a full QA cycle and release process which validates the content of the release branch. There may be patches merged onto the stable release branches as and when they become available however.

The convention is for the stable release branches to have strong maintainship and releases for around a year after their original release. For significant issues, we may backport things to older releases. Beyond this point there is are communuty-lts trees and branches where people share patchs for older releases but these do not go through the same release process as the point releases. https://wiki.yoctoproject.org/wiki/Stable_branch_maintenance has more information about stable branches.
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pieces in this last paragraph are about to be discussed with the community so might change if there are alternative proposals/suggestions.