diff --git a/hw/ppc/mac_newworld.c b/hw/ppc/mac_newworld.c
index 7e97af4..f5bccd2 100644
--- a/hw/ppc/mac_newworld.c
+++ b/hw/ppc/mac_newworld.c
@@ -204,8 +204,9 @@ static void ppc_core99_init(MachineState *machine)
     memory_region_add_subregion(get_system_memory(), 0, ram);
 
     /* allocate and load BIOS */
-    memory_region_allocate_system_memory(bios, NULL, "ppc_core99.bios",
-                                         BIOS_SIZE);
+    memory_region_init_ram(bios, NULL, "ppc_core99.bios", BIOS_SIZE);
+    vmstate_register_ram_global(bios);
+
     if (bios_name == NULL)
         bios_name = PROM_FILENAME;
     filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
diff --git a/hw/ppc/mac_oldworld.c b/hw/ppc/mac_oldworld.c
index afae825..cd9bdbc 100644
--- a/hw/ppc/mac_oldworld.c
+++ b/hw/ppc/mac_oldworld.c
@@ -135,8 +135,9 @@ static void ppc_heathrow_init(MachineState *machine)
     memory_region_add_subregion(sysmem, 0, ram);
 
     /* allocate and load BIOS */
-    memory_region_allocate_system_memory(bios, NULL, "ppc_heathrow.bios",
-                                         BIOS_SIZE);
+    memory_region_init_ram(bios, NULL, "ppc_heathrow.bios", BIOS_SIZE);
+    vmstate_register_ram_global(bios);
+
     if (bios_name == NULL)
         bios_name = PROM_FILENAME;
     filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
diff --git a/hw/ppc/ppc405_boards.c b/hw/ppc/ppc405_boards.c
index 6b566cd..11d3379 100644
--- a/hw/ppc/ppc405_boards.c
+++ b/hw/ppc/ppc405_boards.c
@@ -214,7 +214,8 @@ static void ref405ep_init(MachineState *machine)
                         33333333, &pic, kernel_filename == NULL ? 0 : 1);
     /* allocate SRAM */
     sram_size = 512 * 1024;
-    memory_region_allocate_system_memory(sram, NULL, "ef405ep.sram", sram_size);
+    memory_region_init_ram(sram, NULL, "ef405ep.sram", sram_size);
+    vmstate_register_ram_global(sram);
     memory_region_add_subregion(sysmem, 0xFFF00000, sram);
     /* allocate and load BIOS */
 #ifdef DEBUG_BOARD_INIT
@@ -245,8 +246,9 @@ static void ref405ep_init(MachineState *machine)
         printf("Load BIOS from file\n");
 #endif
         bios = g_new(MemoryRegion, 1);
-        memory_region_allocate_system_memory(bios, NULL, "ef405ep.bios",
-                                             BIOS_SIZE);
+        memory_region_init_ram(bios, NULL, "ef405ep.bios", BIOS_SIZE);
+        vmstate_register_ram_global(bios);
+
         if (bios_name == NULL)
             bios_name = BIOS_FILENAME;
         filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
@@ -508,6 +510,7 @@ static void taihu_405ep_init(MachineState *machine)
     MemoryRegion *sysmem = get_system_memory();
     MemoryRegion *bios;
     MemoryRegion *ram_memories = g_malloc(2 * sizeof(*ram_memories));
+    MemoryRegion *ram = g_malloc0(sizeof(*ram));
     hwaddr ram_bases[2], ram_sizes[2];
     long bios_size;
     target_ulong kernel_base, initrd_base;
@@ -517,15 +520,20 @@ static void taihu_405ep_init(MachineState *machine)
     DriveInfo *dinfo;
 
     /* RAM is soldered to the board so the size cannot be changed */
-    memory_region_allocate_system_memory(&ram_memories[0], NULL,
-                           "taihu_405ep.ram-0", 0x04000000);
+    ram_size = 0x08000000;
+    memory_region_allocate_system_memory(ram, NULL, "taihu_405ep.ram",
+                                         ram_size);
+
     ram_bases[0] = 0;
     ram_sizes[0] = 0x04000000;
-    memory_region_allocate_system_memory(&ram_memories[1], NULL,
-                           "taihu_405ep.ram-1", 0x04000000);
+    memory_region_init_alias(&ram_memories[0], NULL,
+                             "taihu_405ep.ram-0", ram, ram_bases[0],
+                             ram_sizes[0]);
     ram_bases[1] = 0x04000000;
     ram_sizes[1] = 0x04000000;
-    ram_size = 0x08000000;
+    memory_region_init_alias(&ram_memories[1], NULL,
+                             "taihu_405ep.ram-1", ram, ram_bases[1],
+                             ram_sizes[1]);
 #ifdef DEBUG_BOARD_INIT
     printf("%s: register cpu\n", __func__);
 #endif
@@ -564,8 +572,8 @@ static void taihu_405ep_init(MachineState *machine)
         if (bios_name == NULL)
             bios_name = BIOS_FILENAME;
         bios = g_new(MemoryRegion, 1);
-        memory_region_allocate_system_memory(bios, NULL, "taihu_405ep.bios",
-                                             BIOS_SIZE);
+        memory_region_init_ram(bios, NULL, "taihu_405ep.bios", BIOS_SIZE);
+        vmstate_register_ram_global(bios);
         filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
         if (filename) {
             bios_size = load_image(filename, memory_region_get_ram_ptr(bios));
diff --git a/hw/ppc/ppc405_uc.c b/hw/ppc/ppc405_uc.c
index fcd5f2d..a73e918 100644
--- a/hw/ppc/ppc405_uc.c
+++ b/hw/ppc/ppc405_uc.c
@@ -974,8 +974,8 @@ static void ppc405_ocm_init(CPUPPCState *env)
 
     ocm = g_malloc0(sizeof(ppc405_ocm_t));
     /* XXX: Size is 4096 or 0x04000000 */
-    memory_region_allocate_system_memory(&ocm->isarc_ram, NULL, "ppc405.ocm",
-                                         4096);
+    memory_region_init_ram(&ocm->isarc_ram, NULL, "ppc405.ocm", 4096);
+    vmstate_register_ram_global(&ocm->isarc_ram);
     memory_region_init_alias(&ocm->dsarc_ram, NULL, "ppc405.dsarc", &ocm->isarc_ram,
                              0, 4096);
     qemu_register_reset(&ocm_reset, ocm);
diff --git a/hw/ppc/ppc4xx_devs.c b/hw/ppc/ppc4xx_devs.c
index 07f9d00..2b5d2cd 100644
--- a/hw/ppc/ppc4xx_devs.c
+++ b/hw/ppc/ppc4xx_devs.c
@@ -683,28 +683,20 @@ ram_addr_t ppc4xx_sdram_adjust(ram_addr_t ram_size, int nr_banks,
                                hwaddr ram_sizes[],
                                const unsigned int sdram_bank_sizes[])
 {
+    MemoryRegion *ram = g_malloc0(sizeof(*ram));
     ram_addr_t size_left = ram_size;
     ram_addr_t base = 0;
+    unsigned int bank_size;
     int i;
     int j;
 
     for (i = 0; i < nr_banks; i++) {
         for (j = 0; sdram_bank_sizes[j] != 0; j++) {
-            unsigned int bank_size = sdram_bank_sizes[j];
-
+            bank_size = sdram_bank_sizes[j];
             if (bank_size <= size_left) {
-                char name[32];
-                snprintf(name, sizeof(name), "ppc4xx.sdram%d", i);
-                memory_region_allocate_system_memory(&ram_memories[i], NULL,
-                                                     name, bank_size);
-                ram_bases[i] = base;
-                ram_sizes[i] = bank_size;
-                base += bank_size;
                 size_left -= bank_size;
-                break;
             }
         }
-
         if (!size_left) {
             /* No need to use the remaining banks. */
             break;
@@ -712,9 +704,31 @@ ram_addr_t ppc4xx_sdram_adjust(ram_addr_t ram_size, int nr_banks,
     }
 
     ram_size -= size_left;
-    if (size_left)
+    if (size_left) {
         printf("Truncating memory to %d MiB to fit SDRAM controller limits.\n",
                (int)(ram_size >> 20));
+    }
+
+    memory_region_allocate_system_memory(ram, NULL, "ppc4xx.sdram", ram_size);
+
+    size_left = ram_size;
+    for (i = 0; i < nr_banks && size_left; i++) {
+        for (j = 0; sdram_bank_sizes[j] != 0; j++) {
+            bank_size = sdram_bank_sizes[j];
+
+            if (bank_size <= size_left) {
+                char name[32];
+                snprintf(name, sizeof(name), "ppc4xx.sdram%d", i);
+                memory_region_init_alias(&ram_memories[i], NULL, name, ram,
+                                         base, bank_size);
+                ram_bases[i] = base;
+                ram_sizes[i] = bank_size;
+                base += bank_size;
+                size_left -= bank_size;
+                break;
+            }
+        }
+    }
 
     return ram_size;
 }
