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authorIgor Mammedov <imammedo@redhat.com>2021-01-21 11:15:04 -0500
committerPaolo Bonzini <pbonzini@redhat.com>2021-02-08 14:43:54 +0100
commit8db0b20415c129cf5e577a593a4a0372d90b7cc9 (patch)
tree9efe01cbad73866594f7ac420926b1d5848e4482 /backends/hostmem.c
parent5ea9e9e239db83391a39c09f1de63c4099c20df5 (diff)
machine: add missing doc for memory-backend option
Add documentation for '-machine memory-backend' CLI option and how to use it. And document that x-use-canonical-path-for-ramblock-id, is considered to be stable to make sure it won't go away by accident. x- was intended for unstable/iternal properties, and not supposed to be stable option. However it's too late to rename (drop x-) it as it would mean that users will have to mantain both x-use-canonical-path-for-ramblock-id (for QEMU 5.0-5.2) versions and prefix-less for later versions. Signed-off-by: Igor Mammedov <imammedo@redhat.com> Message-Id: <20210121161504.1007247-1-imammedo@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'backends/hostmem.c')
-rw-r--r--backends/hostmem.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/backends/hostmem.c b/backends/hostmem.c
index be0c3b079f..c6c1ff5b99 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -494,6 +494,16 @@ host_memory_backend_class_init(ObjectClass *oc, void *data)
host_memory_backend_get_share, host_memory_backend_set_share);
object_class_property_set_description(oc, "share",
"Mark the memory as private to QEMU or shared");
+ /*
+ * Do not delete/rename option. This option must be considered stable
+ * (as if it didn't have the 'x-' prefix including deprecation period) as
+ * long as 4.0 and older machine types exists.
+ * Option will be used by upper layers to override (disable) canonical path
+ * for ramblock-id set by compat properties on old machine types ( <= 4.0),
+ * to keep migration working when backend is used for main RAM with
+ * -machine memory-backend= option (main RAM historically used prefix-less
+ * ramblock-id).
+ */
object_class_property_add_bool(oc, "x-use-canonical-path-for-ramblock-id",
host_memory_backend_get_use_canonical_path,
host_memory_backend_set_use_canonical_path);