[PATCH weston 2/2] README: updates on libweston versioning

[Pekka Paalanen]

From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>

WE have agreed to use the major as the ABI-version, so talk about major
to avoid confusion.

Remove unncessary or incorrect wording related to breaking ABI on minor
bumps.

Explain a little about the weston vs. libweston version numbers.

Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
---
 README | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/README b/README
index 37090d5..0275c09 100644
--- a/README
+++ b/README
@@ -36,7 +36,7 @@ input and output systems, so that people who just want to write a new
 "Wayland window manager" (WM) or a small desktop environment (DE) can
 focus on the WM part.
 
-Libweston was first introduced in Weston 1.9, and is expected to
+Libweston was first introduced in Weston 1.12, and is expected to
 continue evolving through many Weston releases before it achieves a
 stable API and feature completeness.
 
@@ -45,23 +45,17 @@ API/ABI (in)stability and parallel installability
 -------------------------------------------------
 
 As libweston's API surface is huge, it is impossible to get it right
-in one go. Therefore developers reserve the right to break the API/ABI
-between every 1.x.0 Weston release (minor version bumps), just like
-Weston's plugin API does. For git snapshots of the master branch, the
-API/ABI can break any time without warning or version bump.
-
-Libweston API or ABI will not be broken between Weston's stable
-releases 1.x.0 and 1.x.y, where y < 90.
+in one go. Therefore developers reserve the right to break the API/ABI and bump
+the major version to signify that. For git snapshots of the master branch, the
+API/ABI can break any time without warning.
 
 To make things tolerable for libweston users despite API/ABI breakages,
-libweston is designed to be perfectly parallel-installable. An
-API/ABI-version is defined for libweston, and it is bumped for releases as
-needed. Different non-backward compatible ABI versions of libweston can be
-installed in parallel, so that external projects can easily depend on a
-particular ABI-version. Thus they do not have to fight over which ABI-version
-is installed in a user's system. This allows a user to install many
-different compositors each requiring a different libweston ABI-version
-without tricks or conflicts.
+different libweston major versions are designed to be perfectly
+parallel-installable. This way external projects can easily depend on a
+particular API/ABI-version. Thus they do not have to fight over which
+ABI-version is installed in a user's system. This allows a user to install many
+different compositors each requiring a different libweston ABI-version without
+tricks or conflicts.
 
 Note, that versions of Weston itself will not be parallel-installable,
 only libweston is.
@@ -82,6 +76,14 @@ The document provides the full details, with the gist summed below:
  - Minor - new backward compatible features.
  - Patch - internal (implementation specific) fixes.
 
+Weston and libweston have separate version numbers in configure.ac. All
+releases are made by the Weston version number. Libweston version number
+matches the Weston version number in all releases except maybe pre-releases.
+Pre-releases have the micro/patch version 91 or greater.
+
+A pre-release is allowed to install a libweston version greater than the
+Weston version.
+
 
 Forward compatibility
 ---------------------
-- 
2.7.3