[oe] Discussion: Version retention policy in oe-core

[Tom Rini]

Hi all,

The TSC has discussed this item at the request of the community and has 
come up with the following recommendation which we are looking for 
feedback (positive/negative/neutral) before putting this up on the wiki.

-------- Original Message --------
Subject: Re: Discussion: Version retention policy in oe-core
Date: Thu, 24 Feb 2011 15:05:25 -0600
From: Mark Hatle <mark.hatle at windriver.com>
Reply-To: tsc at lists.openembedded.org
Organization: Wind River Systems
To: <tsc at lists.openembedded.org>

This is a follow on to Tom's original post.  The attempt is to merge his
original thoughts with my own.

---

As has been discussed in a few places, there needs to be a policy that
is followed about how long to retain (or when to replace) old recipes
within the oe-core repository as well as what to do with older versions 
of things.

It is expected that OE will have a related meta-oe or similar layers 
which older components can be moved into while they are still useful and 
desirable to maintain.  However, these will be alternative versions and 
not the "core" version any longer.

Within the oe-core we can divide the components into two classes. 
Critical infrastructure components and standard components.  The 
critical components include the toolchain, autotools, and key libraries. 
  Virtually everything else fits into the standard components bucket.

We also have use cases such as:
- Upstream provides provides support (new releases) and clear guidelines
on upgrading for version 4.0 (current), version 3.8 (previous and 
stable) and version 3.6 (further previous, stable).  Upstream is also 
working on version 4.1.x (unstable, active development).
- Upstream provides no clear policy about what's supported other than 
current.
- Community standards indicate a specific version should be used rather 
then the latest for some reason
- An architecture requires specific versions.

We would like to propose the following:

The goal of oe-core is to remain a stable, yet up-to-date set of 
software that forms the foundation of the Open Embedded world.  While 
not everyone will be able to agree on a broad definition of "stable, yet 
up-to-date" the following guidelines will help define the rules for the 
inclusion and/or replacement of different versions into the oe-core.

First, each of the packages need to be divided into two categories: 
Critical Infrastructure and Core components.  If an item is neither of 
these, then the oe-core is likely the wrong place for the component.

By default we want to use the latest stable version of each component. 
The latest stable version of each component is defined by the 
component's upstream. When there is no clear policy from upstream we 
simply have to apply best judgment.

There of course will be exceptions to the default policy.  However, when 
an exception occurs it must be clearly stated and documented when and 
why we did not use the latest stable version -- or why we may have 
multiple versions available of a given component.  This will allow us to 
reevaluate the exceptions on a timely basis and decide the exception is 
no longer reasonable.

Most of these exceptions will be located in the critical infrastructure
components, specifically the toolchains.  In many cases we will need to 
support variants of these components either for stability or 
architectural reasons.

Another common exception is to meet specific policy or compatibility 
objectives within the system, such as the need to support both GPLv2 and 
GPLv3 versions of selected components.

If multiple versions are provided, usually the latest stable version 
will be preferred, however best judgment will be used to determine the 
preferred version.

As existing versions of removed, if they are still desirable, they 
should be moved into meta-oe or a suitable layer.

We also have the issue of upcoming development versions it is suggested 
that upcoming development versions of software be worked on in specific 
development layers until they have reach sufficient maturity to be 
considered stable and ready for inclusion in oe-core.

Related to this are:
- We want to encourage distributions that are tracking the latest to try 
and stay with the latest.
- We want to encourage recipes which people are interested in to be 
maintained long term to be maintained, long term, in meta-oe.
- We want to encourage distributions to work with and add to / maintain 
the core rather than deciding we have too frequent of an unhelpful churn 
(which is to say 4.0.1 -> 4.0.2 of $whatever is good, 4.0.1 -> 4.4.3 of 
$whatever is not).