qapi-schema: Comment about full expansion of non-migration-safe models

Add a note warning that static expansion may not be 100% accurate
when the CPU model is not migration-safe. This will be the case
on x86 when expansing the "host" CPU model, because there are
"host" features that can't have a migration-safe representation
(e.g. "host-cache-info").

Message-Id: <20170116211124.29245-3-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

diff --git a/qapi-schema.json b/qapi-schema.json
index 150ee98e9e67af5fdf63aec00442539c9a594387..2051c46cfcc45f3135a550303cc0e07b056be648 100644 (file)
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -4274,6 +4274,15 @@
 #        migration-safe, but allows tooling to get an insight and work with
 #        model details.
 #
+# Note: When a non-migration-safe CPU model is expanded in static mode, some
+# features enabled by the CPU model may be omitted, because they can't be
+# implemented by a static CPU model definition (e.g. cache info passthrough and
+# PMU passthrough in x86). If you need an accurate representation of the
+# features enabled by a non-migration-safe CPU model, use @full. If you need a
+# static representation that will keep ABI compatibility even when changing QEMU
+# version or machine-type, use @static (but keep in mind that some features may
+# be omitted).
+#
 # Since: 2.8.0
 ##
 { 'enum': 'CpuModelExpansionType',