docs/about/deprecated: auto-generate a note for versioned machine types

We deprecate versioned machine types on a fixed schedule. This allows us
to auto-generate a paragraph in the deprecated.rst document that always
has accurate version info.

Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

docs/about/deprecated.rst

@@ -278,6 +278,13 @@ CPU implementation for a while before removing all support.
 System emulator machines
 ------------------------
 
+Versioned machine types (aarch64, arm, i386, m68k, ppc64, s390x, x86_64)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+In accordance with our versioned machine type deprecation policy, all machine
+types with version |VER_MACHINE_DEPRECATION_VERSION|, or older, have been
+deprecated.
+
 Arm ``virt`` machine ``dtb-kaslr-seed`` property (since 7.1)
 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
 

docs/conf.py

@@ -117,6 +117,27 @@ finally:
     else:
         version = release = "unknown version"
 
+bits = version.split(".")
+
+major = int(bits[0])
+minor = int(bits[1])
+micro = int(bits[2])
+
+# Check for a dev snapshot, so we can adjust to next
+# predicted release version.
+#
+# This assumes we do 3 releases per year, so must bump
+# major if minor == 2
+if micro >= 50:
+    micro = 0
+    if minor == 2:
+        major += 1
+        minor = 0
+    else:
+        minor += 1
+
+ver_machine_deprecation_version = "%d.%d.0" % (major - 3, minor)
+
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
 #
@@ -145,7 +166,17 @@ suppress_warnings = ["ref.option"]
 # environment variable is not set is for the benefit of readthedocs
 # style document building; our Makefile always sets the variable.
 confdir = os.getenv('CONFDIR', "/etc/qemu")
-rst_epilog = ".. |CONFDIR| replace:: ``" + confdir + "``\n"
+
+vars = {
+    "CONFDIR": confdir,
+    "VER_MACHINE_DEPRECATION_VERSION": ver_machine_deprecation_version,
+}
+
+rst_epilog = "".join([
+    ".. |" + key + "| replace:: ``" + vars[key] + "``\n"
+    for key in vars.keys()
+])
+
 # We slurp in the defs.rst.inc and literally include it into rst_epilog,
 # because Sphinx's include:: directive doesn't work with absolute paths
 # and there isn't any one single relative path that will work for all