diff --git a/hw/xilinx_ethlite.c b/hw/xilinx_ethlite.c
index f35ba84..6f44c84 100644
--- a/hw/xilinx_ethlite.c
+++ b/hw/xilinx_ethlite.c
@@ -50,6 +50,7 @@
 struct xlx_ethlite
 {
     SysBusDevice busdev;
+    MemoryRegion mmio;
     qemu_irq irq;
     NICState *nic;
     NICConf conf;
@@ -70,7 +71,8 @@ static inline void eth_pulse_irq(struct xlx_ethlite *s)
     }
 }
 
-static uint32_t eth_readl (void *opaque, target_phys_addr_t addr)
+static uint64_t
+eth_read(void *opaque, target_phys_addr_t addr, unsigned int size)
 {
     struct xlx_ethlite *s = opaque;
     uint32_t r = 0;
@@ -98,10 +100,12 @@ static uint32_t eth_readl (void *opaque, target_phys_addr_t addr)
 }
 
 static void
-eth_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
+eth_write(void *opaque, target_phys_addr_t addr,
+          uint64_t val64, unsigned int size)
 {
     struct xlx_ethlite *s = opaque;
     unsigned int base = 0;
+    uint32_t value = val64;
 
     addr >>= 2;
     switch (addr) 
@@ -146,12 +150,14 @@ eth_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
     }
 }
 
-static CPUReadMemoryFunc * const eth_read[] = {
-    NULL, NULL, &eth_readl,
-};
-
-static CPUWriteMemoryFunc * const eth_write[] = {
-    NULL, NULL, &eth_writel,
+static const MemoryRegionOps eth_ops = {
+    .read = eth_read,
+    .write = eth_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4
+    }
 };
 
 static int eth_can_rx(VLANClientState *nc)
@@ -206,13 +212,12 @@ static NetClientInfo net_xilinx_ethlite_info = {
 static int xilinx_ethlite_init(SysBusDevice *dev)
 {
     struct xlx_ethlite *s = FROM_SYSBUS(typeof (*s), dev);
-    int regs;
 
     sysbus_init_irq(dev, &s->irq);
     s->rxbuf = 0;
 
-    regs = cpu_register_io_memory(eth_read, eth_write, s, DEVICE_NATIVE_ENDIAN);
-    sysbus_init_mmio(dev, R_MAX * 4, regs);
+    memory_region_init_io(&s->mmio, &eth_ops, s, "xilinx-ethlite", R_MAX * 4);
+    sysbus_init_mmio_region(dev, &s->mmio);
 
     qemu_macaddr_default_if_unset(&s->conf.macaddr);
     s->nic = qemu_new_nic(&net_xilinx_ethlite_info, &s->conf,
diff --git a/hw/xilinx_intc.c b/hw/xilinx_intc.c
index cb72d5a..58b73d9 100644
--- a/hw/xilinx_intc.c
+++ b/hw/xilinx_intc.c
@@ -40,6 +40,7 @@
 struct xlx_pic
 {
     SysBusDevice busdev;
+    MemoryRegion mmio;
     qemu_irq parent_irq;
 
     /* Configuration reg chosen at synthesis-time. QEMU populates
@@ -72,7 +73,8 @@ static void update_irq(struct xlx_pic *p)
     }
 }
 
-static uint32_t pic_readl (void *opaque, target_phys_addr_t addr)
+static uint64_t
+pic_read(void *opaque, target_phys_addr_t addr, unsigned int size)
 {
     struct xlx_pic *p = opaque;
     uint32_t r = 0;
@@ -91,9 +93,11 @@ static uint32_t pic_readl (void *opaque, target_phys_addr_t addr)
 }
 
 static void
-pic_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
+pic_write(void *opaque, target_phys_addr_t addr,
+          uint64_t val64, unsigned int size)
 {
     struct xlx_pic *p = opaque;
+    uint32_t value = val64;
 
     addr >>= 2;
     D(qemu_log("%s addr=%x val=%x\n", __func__, addr * 4, value));
@@ -116,14 +120,14 @@ pic_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
     update_irq(p);
 }
 
-static CPUReadMemoryFunc * const pic_read[] = {
-    NULL, NULL,
-    &pic_readl,
-};
-
-static CPUWriteMemoryFunc * const pic_write[] = {
-    NULL, NULL,
-    &pic_writel,
+static const MemoryRegionOps pic_ops = {
+    .read = pic_read,
+    .write = pic_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4
+    }
 };
 
 static void irq_handler(void *opaque, int irq, int level)
@@ -148,13 +152,12 @@ static void irq_handler(void *opaque, int irq, int level)
 static int xilinx_intc_init(SysBusDevice *dev)
 {
     struct xlx_pic *p = FROM_SYSBUS(typeof (*p), dev);
-    int pic_regs;
 
     qdev_init_gpio_in(&dev->qdev, irq_handler, 32);
     sysbus_init_irq(dev, &p->parent_irq);
 
-    pic_regs = cpu_register_io_memory(pic_read, pic_write, p, DEVICE_NATIVE_ENDIAN);
-    sysbus_init_mmio(dev, R_MAX * 4, pic_regs);
+    memory_region_init_io(&p->mmio, &pic_ops, p, "xilinx-pic", R_MAX * 4);
+    sysbus_init_mmio_region(dev, &p->mmio);
     return 0;
 }
 
diff --git a/hw/xilinx_timer.c b/hw/xilinx_timer.c
index f1c7abc..8779c56 100644
--- a/hw/xilinx_timer.c
+++ b/hw/xilinx_timer.c
@@ -59,6 +59,7 @@ struct xlx_timer
 struct timerblock
 {
     SysBusDevice busdev;
+    MemoryRegion mmio;
     qemu_irq irq;
     uint32_t nr_timers;
     uint32_t freq_hz;
@@ -85,7 +86,8 @@ static void timer_update_irq(struct timerblock *t)
     qemu_set_irq(t->irq, !!irq);
 }
 
-static uint32_t timer_readl (void *opaque, target_phys_addr_t addr)
+static uint64_t
+timer_read(void *opaque, target_phys_addr_t addr, unsigned int size)
 {
     struct timerblock *t = opaque;
     struct xlx_timer *xt;
@@ -134,11 +136,13 @@ static void timer_enable(struct xlx_timer *xt)
 }
 
 static void
-timer_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
+timer_write(void *opaque, target_phys_addr_t addr,
+            uint64_t val64, unsigned int size)
 {
     struct timerblock *t = opaque;
     struct xlx_timer *xt;
     unsigned int timer;
+    uint32_t value = val64;
 
     addr >>= 2;
     timer = timer_from_addr(addr);
@@ -166,14 +170,14 @@ timer_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
     timer_update_irq(t);
 }
 
-static CPUReadMemoryFunc * const timer_read[] = {
-    NULL, NULL,
-    &timer_readl,
-};
-
-static CPUWriteMemoryFunc * const timer_write[] = {
-    NULL, NULL,
-    &timer_writel,
+static const MemoryRegionOps timer_ops = {
+    .read = timer_read,
+    .write = timer_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid = {
+        .min_access_size = 4,
+        .max_access_size = 4
+    }
 };
 
 static void timer_hit(void *opaque)
@@ -192,7 +196,6 @@ static int xilinx_timer_init(SysBusDevice *dev)
 {
     struct timerblock *t = FROM_SYSBUS(typeof (*t), dev);
     unsigned int i;
-    int timer_regs;
 
     /* All timers share a single irq line.  */
     sysbus_init_irq(dev, &t->irq);
@@ -209,9 +212,9 @@ static int xilinx_timer_init(SysBusDevice *dev)
         ptimer_set_freq(xt->ptimer, t->freq_hz);
     }
 
-    timer_regs = cpu_register_io_memory(timer_read, timer_write, t,
-                                        DEVICE_NATIVE_ENDIAN);
-    sysbus_init_mmio(dev, R_MAX * 4 * t->nr_timers, timer_regs);
+    memory_region_init_io(&t->mmio, &timer_ops, t, "xilinx-timer",
+                          R_MAX * 4 * t->nr_timers);
+    sysbus_init_mmio_region(dev, &t->mmio);
     return 0;
 }
 
diff --git a/hw/xilinx_uartlite.c b/hw/xilinx_uartlite.c
index 467a26c..3b4f75b 100644
--- a/hw/xilinx_uartlite.c
+++ b/hw/xilinx_uartlite.c
@@ -49,6 +49,7 @@
 struct xlx_uartlite
 {
     SysBusDevice busdev;
+    MemoryRegion mmio;
     CharDriverState *chr;
     qemu_irq irq;
 
@@ -82,7 +83,8 @@ static void uart_update_status(struct xlx_uartlite *s)
     s->regs[R_STATUS] = r;
 }
 
-static uint32_t uart_readl (void *opaque, target_phys_addr_t addr)
+static uint64_t
+uart_read(void *opaque, target_phys_addr_t addr, unsigned int size)
 {
     struct xlx_uartlite *s = opaque;
     uint32_t r = 0;
@@ -107,9 +109,11 @@ static uint32_t uart_readl (void *opaque, target_phys_addr_t addr)
 }
 
 static void
-uart_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
+uart_write(void *opaque, target_phys_addr_t addr,
+           uint64_t val64, unsigned int size)
 {
     struct xlx_uartlite *s = opaque;
+    uint32_t value = val64;
     unsigned char ch = value;
 
     addr >>= 2;
@@ -147,16 +151,14 @@ uart_writel (void *opaque, target_phys_addr_t addr, uint32_t value)
     uart_update_irq(s);
 }
 
-static CPUReadMemoryFunc * const uart_read[] = {
-    &uart_readl,
-    &uart_readl,
-    &uart_readl,
-};
-
-static CPUWriteMemoryFunc * const uart_write[] = {
-    &uart_writel,
-    &uart_writel,
-    &uart_writel,
+static const MemoryRegionOps uart_ops = {
+    .read = uart_read,
+    .write = uart_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid = {
+        .min_access_size = 1,
+        .max_access_size = 4
+    }
 };
 
 static void uart_rx(void *opaque, const uint8_t *buf, int size)
@@ -196,14 +198,13 @@ static void uart_event(void *opaque, int event)
 static int xilinx_uartlite_init(SysBusDevice *dev)
 {
     struct xlx_uartlite *s = FROM_SYSBUS(typeof (*s), dev);
-    int uart_regs;
 
     sysbus_init_irq(dev, &s->irq);
 
     uart_update_status(s);
-    uart_regs = cpu_register_io_memory(uart_read, uart_write, s,
-                                       DEVICE_NATIVE_ENDIAN);
-    sysbus_init_mmio(dev, R_MAX * 4, uart_regs);
+    memory_region_init_io(&s->mmio, &uart_ops, s, "xilinx-uartlite", R_MAX * 4);
+    sysbus_init_mmio_region(dev, &s->mmio);
+
 
     s->chr = qdev_init_chardev(&dev->qdev);
     if (s->chr)
