diff --git a/exec.c b/exec.c
index 8ffde75..0989933 100644
--- a/exec.c
+++ b/exec.c
@@ -2715,11 +2715,13 @@ void cpu_physical_memory_rw(hwaddr addr, uint8_t *buf,
 
 enum write_rom_type {
     WRITE_DATA,
+    READ_DATA,
     FLUSH_CACHE,
 };
 
-static inline void cpu_physical_memory_write_rom_internal(AddressSpace *as,
-    hwaddr addr, const uint8_t *buf, int len, enum write_rom_type type)
+static inline void cpu_physical_memory_rw_debug_internal(AddressSpace *as,
+    hwaddr addr, uint8_t *buf, int len, MemTxAttrs attrs,
+    enum write_rom_type type)
 {
     hwaddr l;
     uint8_t *ptr;
@@ -2733,13 +2735,33 @@ static inline void cpu_physical_memory_write_rom_internal(AddressSpace *as,
 
         if (!(memory_region_is_ram(mr) ||
               memory_region_is_romd(mr))) {
-            l = memory_access_size(mr, l, addr1);
+            /* Pass MMIO down to address address_space_rw */
+            switch (type) {
+            case READ_DATA:
+            case WRITE_DATA:
+                address_space_rw(as, addr, attrs, buf, l,
+                                 type == WRITE_DATA);
+                break;
+            case FLUSH_CACHE:
+                break;
+            }
         } else {
             /* ROM/RAM case */
             ptr = qemu_map_ram_ptr(mr->ram_block, addr1);
             switch (type) {
+            case READ_DATA:
+                if (mr->ram_ops) {
+                    mr->ram_ops->read(buf, ptr, l, attrs);
+                } else {
+                    memcpy(buf, ptr, l);
+                }
+                break;
             case WRITE_DATA:
-                memcpy(ptr, buf, l);
+                if (mr->ram_ops) {
+                    mr->ram_ops->write(ptr, buf, l, attrs);
+                } else {
+                    memcpy(ptr, buf, l);
+                }
                 invalidate_and_set_dirty(mr, addr1, l);
                 break;
             case FLUSH_CACHE:
@@ -2756,9 +2778,10 @@ static inline void cpu_physical_memory_write_rom_internal(AddressSpace *as,
 
 /* used for ROM loading : can write in RAM and ROM */
 void cpu_physical_memory_write_rom(AddressSpace *as, hwaddr addr,
-                                   const uint8_t *buf, int len)
+                                   uint8_t *buf, int len)
 {
-    cpu_physical_memory_write_rom_internal(as, addr, buf, len, WRITE_DATA);
+    cpu_physical_memory_rw_debug_internal(as, addr, buf, len,
+            MEMTXATTRS_UNSPECIFIED, WRITE_DATA);
 }
 
 void cpu_flush_icache_range(hwaddr start, int len)
@@ -2773,8 +2796,10 @@ void cpu_flush_icache_range(hwaddr start, int len)
         return;
     }
 
-    cpu_physical_memory_write_rom_internal(&address_space_memory,
-                                           start, NULL, len, FLUSH_CACHE);
+    cpu_physical_memory_rw_debug_internal(&address_space_memory,
+                                           start, NULL, len,
+                                           MEMTXATTRS_UNSPECIFIED,
+                                           FLUSH_CACHE);
 }
 
 typedef struct {
@@ -3597,6 +3622,7 @@ int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
     int l;
     hwaddr phys_addr;
     target_ulong page;
+    int type = is_write ? WRITE_DATA : READ_DATA;
 
     while (len > 0) {
         int asidx;
@@ -3605,6 +3631,10 @@ int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
         page = addr & TARGET_PAGE_MASK;
         phys_addr = cpu_get_phys_page_attrs_debug(cpu, page, &attrs);
         asidx = cpu_asidx_from_attrs(cpu, attrs);
+
+        /* set debug attribute */
+        attrs.debug = 1;
+
         /* if no physical page mapped, return an error */
         if (phys_addr == -1)
             return -1;
@@ -3612,14 +3642,9 @@ int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
         if (l > len)
             l = len;
         phys_addr += (addr & ~TARGET_PAGE_MASK);
-        if (is_write) {
-            cpu_physical_memory_write_rom(cpu->cpu_ases[asidx].as,
-                                          phys_addr, buf, l);
-        } else {
-            address_space_rw(cpu->cpu_ases[asidx].as, phys_addr,
-                             MEMTXATTRS_UNSPECIFIED,
-                             buf, l, 0);
-        }
+        cpu_physical_memory_rw_debug_internal(cpu->cpu_ases[asidx].as,
+                                               phys_addr, buf, l, attrs,
+                                               type);
         len -= l;
         buf += l;
         addr += l;
diff --git a/include/exec/cpu-common.h b/include/exec/cpu-common.h
index 952bcfe..520dae0 100644
--- a/include/exec/cpu-common.h
+++ b/include/exec/cpu-common.h
@@ -104,7 +104,7 @@ void stq_le_phys(AddressSpace *as, hwaddr addr, uint64_t val);
 void stq_be_phys(AddressSpace *as, hwaddr addr, uint64_t val);
 
 void cpu_physical_memory_write_rom(AddressSpace *as, hwaddr addr,
-                                   const uint8_t *buf, int len);
+                                   uint8_t *buf, int len);
 void cpu_flush_icache_range(hwaddr start, int len);
 
 extern struct MemoryRegion io_mem_rom;
diff --git a/include/exec/memory.h b/include/exec/memory.h
index 3e4d416..80af3b0 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -146,6 +146,18 @@ struct MemoryRegionOps {
     const MemoryRegionMmio old_mmio;
 };
 
+/* Memory Region RAM callback */
+typedef struct MemoryRegionRAMReadWriteOps MemoryRegionRAMReadWriteOps;
+
+struct MemoryRegionRAMReadWriteOps {
+    /* Write data into guest memory */
+    int (*write) (uint8_t *dest, const uint8_t *src,
+                  uint32_t len, MemTxAttrs attrs);
+    /* Read data from guest memory */
+    int (*read) (uint8_t *dest, const uint8_t *src,
+                 uint32_t len, MemTxAttrs attrs);
+};
+
 typedef struct MemoryRegionIOMMUOps MemoryRegionIOMMUOps;
 
 struct MemoryRegionIOMMUOps {
@@ -179,6 +191,7 @@ struct MemoryRegion {
     RAMBlock *ram_block;
     Object *owner;
     const MemoryRegionIOMMUOps *iommu_ops;
+    const MemoryRegionRAMReadWriteOps *ram_ops;
 
     const MemoryRegionOps *ops;
     void *opaque;
@@ -506,6 +519,18 @@ static inline void memory_region_init_reservation(MemoryRegion *mr,
 }
 
 /**
+ * memory_region_set_ram_ops: Set the Read/Write ops for accessing the RAM
+ *
+ * @mr: the #MemoryRegion to be initialized
+ * @ops: a function that will be used to read/write @target region
+ */
+static inline void memory_region_set_ram_ops(MemoryRegion *mr,
+                               const MemoryRegionRAMReadWriteOps *ops)
+{
+    mr->ram_ops = ops;
+}
+
+/**
  * memory_region_init_iommu: Initialize a memory region that translates
  * addresses
  *
