Backward compatibility: the key store with drivers
Promise that we will try to keep backward compatibility with basic driver
usage, but not with more experimental aspects.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/BRANCHES.md b/BRANCHES.md
index e08ae87..f6cdd65 100644
--- a/BRANCHES.md
+++ b/BRANCHES.md
@@ -78,6 +78,12 @@
LTS, but future major version upgrades (for example from 2.28.x/3.x to 4.y)
may require the use of an upgrade tool.
+Note that this guarantee does not currently fully extend to drivers, which
+are an experimental feature. We intend to maintain compatibility with the
+basic use of drivers from Mbed TLS 2.28.0 onwards, even if driver APIs
+change. However, for more experimental parts of the driver interface, such
+as the use of driver state, we do not yet guarantee backward compatibility.
+
## Long-time support branches
For the LTS branches, additionally we try very hard to also maintain ABI