memory_region_allocate_system_memory() API is going away, so
replace it with memdev allocated MemoryRegion. The later is
initialized by generic code, so board only needs to opt in
to memdev scheme by providing
  MachineClass::default_ram_id
and using MachineState::ram instead of manually initializing
RAM memory region.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
CC: mst@redhat.com
CC: pbonzini@redhat.com
CC: rth@twiddle.net
CC: ehabkost@redhat.com
---
 hw/i386/pc.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 2ddce4230a..6ab4acb0c6 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -937,7 +937,7 @@ void pc_memory_init(PCMachineState *pcms,
                     MemoryRegion **ram_memory)
 {
     int linux_boot, i;
-    MemoryRegion *ram, *option_rom_mr;
+    MemoryRegion *option_rom_mr;
     MemoryRegion *ram_below_4g, *ram_above_4g;
     FWCfgState *fw_cfg;
     MachineState *machine = MACHINE(pcms);
@@ -950,22 +950,20 @@ void pc_memory_init(PCMachineState *pcms,
 
     linux_boot = (machine->kernel_filename != NULL);
 
-    /* Allocate RAM.  We allocate it as a single memory region and use
-     * aliases to address portions of it, mostly for backwards compatibility
-     * with older qemus that used qemu_ram_alloc().
+    /*
+     * Split single memory region and use aliases to address portions of it,
+     * done for backwards compatibility with older qemus.
      */
-    ram = g_malloc(sizeof(*ram));
-    memory_region_allocate_system_memory(ram, NULL, "pc.ram",
-                                         machine->ram_size);
-    *ram_memory = ram;
+    *ram_memory = machine->ram;
     ram_below_4g = g_malloc(sizeof(*ram_below_4g));
-    memory_region_init_alias(ram_below_4g, NULL, "ram-below-4g", ram,
+    memory_region_init_alias(ram_below_4g, NULL, "ram-below-4g", machine->ram,
                              0, x86ms->below_4g_mem_size);
     memory_region_add_subregion(system_memory, 0, ram_below_4g);
     e820_add_entry(0, x86ms->below_4g_mem_size, E820_RAM);
     if (x86ms->above_4g_mem_size > 0) {
         ram_above_4g = g_malloc(sizeof(*ram_above_4g));
-        memory_region_init_alias(ram_above_4g, NULL, "ram-above-4g", ram,
+        memory_region_init_alias(ram_above_4g, NULL, "ram-above-4g",
+                                 machine->ram,
                                  x86ms->below_4g_mem_size,
                                  x86ms->above_4g_mem_size);
         memory_region_add_subregion(system_memory, 0x100000000ULL,
@@ -1952,6 +1950,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     mc->default_cpu_type = TARGET_DEFAULT_CPU_TYPE;
     mc->nvdimm_supported = true;
     mc->numa_mem_supported = true;
+    mc->default_ram_id = "pc.ram";
 
     object_class_property_add(oc, PC_MACHINE_DEVMEM_REGION_SIZE, "int",
         pc_machine_get_device_memory_region_size, NULL,
-- 
2.18.1