machine: alias -mem-path and -mem-prealloc into memory-foo backend

Allow machine to opt in for hostmem backend based initial RAM
even if user uses old -mem-path/prealloc options by providing
  MachineClass::default_ram_id
Follow up patches will incrementally convert machines to new API,
by dropping memory_region_allocate_system_memory() and setting
default_ram_id that board used to use before conversion to keep
migration stream the same.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20200219160953.13771-4-imammedo@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 7b4b6b79d7..8e536cafb2 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -170,6 +170,13 @@ typedef struct {
  *    false is returned, an error must be set to show the reason of
  *    the rejection.  If the hook is not provided, all hotplug will be
  *    allowed.
+ * @default_ram_id:
+ *    Specifies inital RAM MemoryRegion name to be used for default backend
+ *    creation if user explicitly hasn't specified backend with "memory-backend"
+ *    property.
+ *    It also will be used as a way to optin into "-m" option support.
+ *    If it's not set by board, '-m' will be ignored and generic code will
+ *    not create default RAM MemoryRegion.
  */
 struct MachineClass {
     /*< private >*/
@@ -226,6 +233,7 @@ struct MachineClass {
     bool nvdimm_supported;
     bool numa_mem_supported;
     bool auto_enable_numa;
+    const char *default_ram_id;
 
     HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
                                            DeviceState *dev);