diff --git a/hw/ppc/ppc440.h b/hw/ppc/ppc440.h
index 01d76b8000..29f6f14ed7 100644
--- a/hw/ppc/ppc440.h
+++ b/hw/ppc/ppc440.h
@@ -11,13 +11,13 @@
 #ifndef PPC440_H
 #define PPC440_H
 
-#include "hw/ppc/ppc4xx.h"
+#include "hw/ppc/ppc.h"
 
 void ppc4xx_l2sram_init(CPUPPCState *env);
 void ppc4xx_cpr_init(CPUPPCState *env);
 void ppc4xx_sdr_init(CPUPPCState *env);
 void ppc440_sdram_init(CPUPPCState *env, int nbanks,
-                       Ppc4xxSdramBank *ram_banks);
+                       MemoryRegion *ram);
 void ppc4xx_ahb_init(CPUPPCState *env);
 void ppc4xx_dma_init(CPUPPCState *env, int dcr_base);
 void ppc460ex_pcie_init(CPUPPCState *env);
diff --git a/hw/ppc/ppc440_uc.c b/hw/ppc/ppc440_uc.c
index edd0781eb7..dd873d892c 100644
--- a/hw/ppc/ppc440_uc.c
+++ b/hw/ppc/ppc440_uc.c
@@ -487,7 +487,7 @@ void ppc4xx_sdr_init(CPUPPCState *env)
 typedef struct ppc440_sdram_t {
     uint32_t addr;
     uint32_t mcopt2;
-    int nbanks;
+    int nbanks; /* Banks to use from the 4, e.g. when board has less slots */
     Ppc4xxSdramBank bank[4];
 } ppc440_sdram_t;
 
@@ -733,18 +733,21 @@ static void sdram_ddr2_reset(void *opaque)
 }
 
 void ppc440_sdram_init(CPUPPCState *env, int nbanks,
-                       Ppc4xxSdramBank *ram_banks)
+                       MemoryRegion *ram)
 {
     ppc440_sdram_t *s;
-    int i;
+    /*
+     * SoC also has 4 GiB but that causes problem with 32 bit
+     * builds (4*GiB overflows the 32 bit ram_addr_t).
+     */
+    const ram_addr_t valid_bank_sizes[] = {
+        2 * GiB, 1 * GiB, 512 * MiB, 256 * MiB, 128 * MiB,
+        64 * MiB, 32 * MiB, 16 * MiB, 8 * MiB, 0
+    };
 
     s = g_malloc0(sizeof(*s));
     s->nbanks = nbanks;
-    for (i = 0; i < nbanks; i++) {
-        s->bank[i].ram = ram_banks[i].ram;
-        s->bank[i].base = ram_banks[i].base;
-        s->bank[i].size = ram_banks[i].size;
-    }
+    ppc4xx_sdram_banks(ram, s->nbanks, s->bank, valid_bank_sizes);
     qemu_register_reset(&sdram_ddr2_reset, s);
     ppc_dcr_register(env, SDRAM0_CFGADDR,
                      s, &sdram_ddr2_dcr_read, &sdram_ddr2_dcr_write);
diff --git a/hw/ppc/sam460ex.c b/hw/ppc/sam460ex.c
index b318521b01..13055a8916 100644
--- a/hw/ppc/sam460ex.c
+++ b/hw/ppc/sam460ex.c
@@ -74,13 +74,6 @@
 #define EBC_FREQ 115000000
 #define UART_FREQ 11059200
 
-/* The SoC could also handle 4 GiB but firmware does not work with that. */
-/* Maybe it overflows a signed 32 bit number somewhere? */
-static const ram_addr_t ppc460ex_sdram_bank_sizes[] = {
-    2 * GiB, 1 * GiB, 512 * MiB, 256 * MiB, 128 * MiB, 64 * MiB,
-    32 * MiB, 0
-};
-
 struct boot_info {
     uint32_t dt_base;
     uint32_t dt_size;
@@ -273,7 +266,6 @@ static void sam460ex_init(MachineState *machine)
 {
     MemoryRegion *address_space_mem = get_system_memory();
     MemoryRegion *isa = g_new(MemoryRegion, 1);
-    Ppc4xxSdramBank *ram_banks = g_new0(Ppc4xxSdramBank, 1);
     MemoryRegion *l2cache_ram = g_new(MemoryRegion, 1);
     DeviceState *uic[4];
     int i;
@@ -340,12 +332,22 @@ static void sam460ex_init(MachineState *machine)
     }
 
     /* SDRAM controller */
-    /* put all RAM on first bank because board has one slot
-     * and firmware only checks that */
-    ppc4xx_sdram_banks(machine->ram, 1, ram_banks, ppc460ex_sdram_bank_sizes);
-
+    /* The SoC could also handle 4 GiB but firmware does not work with that. */
+    if (machine->ram_size > 2 * GiB) {
+        error_report("Memory over 2 GiB is not supported");
+        exit(1);
+    }
+    /* Firmware needs at least 64 MiB */
+    if (machine->ram_size < 64 * MiB) {
+        error_report("Memory below 64 MiB is not supported");
+        exit(1);
+    }
+    /*
+     * Put all RAM on first bank because board has one slot
+     * and firmware only checks that
+     */
+    ppc440_sdram_init(env, 1, machine->ram);
     /* FIXME: does 460EX have ECC interrupts? */
-    ppc440_sdram_init(env, 1, ram_banks);
     /* Enable SDRAM memory regions as we may boot without firmware */
     ppc4xx_sdram_ddr2_enable(env);
 
@@ -354,8 +356,8 @@ static void sam460ex_init(MachineState *machine)
                                qdev_get_gpio_in(uic[0], 2));
     i2c = PPC4xx_I2C(dev)->bus;
     /* SPD EEPROM on RAM module */
-    spd_data = spd_data_generate(ram_banks->size < 128 * MiB ? DDR : DDR2,
-                                 ram_banks->size);
+    spd_data = spd_data_generate(machine->ram_size < 128 * MiB ? DDR : DDR2,
+                                 machine->ram_size);
     spd_data[20] = 4; /* SO-DIMM module */
     smbus_eeprom_init_one(i2c, 0x50, spd_data);
     /* RTC */