[PATCH 4/4] include/hw/boards: add warning about changing deprecation logic

["Daniel P. Berrangé" <berrange@redhat.com>]

If we change the deprecation logic in include/hw/boards.h, we must make
a corresponding change to docs/conf.py and docs/about/deprecated.rst.
Add comments to these files as a warning to future maintainers to keep
these files in sync.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 docs/conf.py        | 4 ++++
 include/hw/boards.h | 6 +++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/docs/conf.py b/docs/conf.py
index 8b567787ce..d0d3cd10ce 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -129,6 +129,10 @@
     else:
         minor += 1
 
+# These thresholds must match the constants
+# MACHINE_VER_DELETION_MAJOR  & MACHINE_VER_DEPRECATION_MAJOR
+# defined in include/hw/boards.h and the introductory text in
+# docs/about/deprecated.rst
 ver_machine_deprecation_version = "%d.%d.%d" % (major - 3, minor, micro)
 ver_machine_deletion_version = "%d.%d.%d" % (major - 6, minor, micro)
 
diff --git a/include/hw/boards.h b/include/hw/boards.h
index dcfb251cbd..a89a885add 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -633,7 +633,11 @@ struct MachineState {
 /*
  * How many years/major releases for each phase
  * of the life cycle. Assumes use of versioning
- * scheme where major is bumped each year
+ * scheme where major is bumped each year.
+ *
+ * These values must match the ver_machine_deprecation_version
+ * and ver_machine_deletion_version logic in docs/conf.py and
+ * the text in docs/about/deprecated.rst
  */
 #define MACHINE_VER_DELETION_MAJOR 6
 #define MACHINE_VER_DEPRECATION_MAJOR 3
-- 
2.47.1