diff --git a/hw/pc.c b/hw/pc.c
index 112739a..2c9664d 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -52,6 +52,7 @@
 #include "arch_init.h"
 #include "bitmap.h"
 #include "vga-pci.h"
+#include "dimm.h"
 
 /* output Bochs bios info messages */
 //#define DEBUG_BIOS
@@ -93,6 +94,9 @@ struct e820_table {
 static struct e820_table e820_table;
 struct hpet_fw_config hpet_cfg = {.count = UINT8_MAX};
 
+ram_addr_t below_4g_hp_mem_size = 0;
+ram_addr_t above_4g_hp_mem_size = 0;
+extern target_phys_addr_t ram_hp_offset;
 void gsi_handler(void *opaque, int n, int level)
 {
     GSIState *s = opaque;
@@ -1160,3 +1164,40 @@ void pc_pci_device_init(PCIBus *pci_bus)
         pci_create_simple(pci_bus, -1, "lsi53c895a");
     }
 }
+
+
+/* Function to configure memory offsets of hotpluggable dimms */
+
+target_phys_addr_t pc_set_hp_memory_offset(uint64_t size)
+{
+    target_phys_addr_t ret;
+
+    /* on first call, initialize ram_hp_offset */
+    if (!ram_hp_offset) {
+        if (ram_size >= PCI_HOLE_START ) {
+            ram_hp_offset = 0x100000000LL + (ram_size - PCI_HOLE_START);
+        } else {
+            ram_hp_offset = ram_size;
+        }
+    }
+
+    if (ram_hp_offset >= 0x100000000LL) {
+        ret = ram_hp_offset;
+        above_4g_hp_mem_size += size;
+        ram_hp_offset += size;
+    }
+    /* if dimm fits before pci hole, append it normally */
+    else if (ram_hp_offset + size <= PCI_HOLE_START) {
+        ret = ram_hp_offset;
+        below_4g_hp_mem_size += size;
+        ram_hp_offset += size;
+    }
+    /* otherwise place it above 4GB */
+    else {
+        ret = 0x100000000LL;
+        above_4g_hp_mem_size += size;
+        ram_hp_offset = 0x100000000LL + size;
+    }
+
+    return ret;
+}
diff --git a/hw/pc.h b/hw/pc.h
index e4db071..f3304fc 100644
--- a/hw/pc.h
+++ b/hw/pc.h
@@ -10,6 +10,7 @@
 #include "memory.h"
 #include "ioapic.h"
 
+#define PCI_HOLE_START 0xe0000000
 /* PC-style peripherals (also used by other machines).  */
 
 /* serial.c */
@@ -214,6 +215,11 @@ static inline bool isa_ne2000_init(ISABus *bus, int base, int irq, NICInfo *nd)
 /* pc_sysfw.c */
 void pc_system_firmware_init(MemoryRegion *rom_memory);
 
+/* memory hotplug */
+target_phys_addr_t pc_set_hp_memory_offset(uint64_t size);
+extern ram_addr_t below_4g_hp_mem_size;
+extern ram_addr_t above_4g_hp_mem_size;
+
 /* e820 types */
 #define E820_RAM        1
 #define E820_RESERVED   2
diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 88ff041..d1fd276 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -43,6 +43,7 @@
 #include "xen.h"
 #include "memory.h"
 #include "exec-memory.h"
+#include "dimm.h"
 #ifdef CONFIG_XEN
 #  include <xen/hvm/hvm_info_table.h>
 #endif
@@ -155,9 +156,9 @@ static void pc_init1(MemoryRegion *system_memory,
         kvmclock_create();
     }
 
-    if (ram_size >= 0xe0000000 ) {
-        above_4g_mem_size = ram_size - 0xe0000000;
-        below_4g_mem_size = 0xe0000000;
+    if (ram_size >= PCI_HOLE_START ) {
+        above_4g_mem_size = ram_size - PCI_HOLE_START;
+        below_4g_mem_size = PCI_HOLE_START;
     } else {
         above_4g_mem_size = 0;
         below_4g_mem_size = ram_size;
@@ -172,6 +173,9 @@ static void pc_init1(MemoryRegion *system_memory,
         rom_memory = system_memory;
     }
 
+    /* adjust memory map for hotplug dimms */
+    dimm_calc_offsets(pc_set_hp_memory_offset);
+
     /* allocate ram and load rom/bios */
     if (!xen_enabled()) {
         fw_cfg = pc_memory_init(system_memory,
@@ -192,9 +196,11 @@ static void pc_init1(MemoryRegion *system_memory,
     if (pci_enabled) {
         pci_bus = i440fx_init(&i440fx_state, &piix3_devfn, &isa_bus, gsi,
                               system_memory, system_io, ram_size,
-                              below_4g_mem_size,
-                              0x100000000ULL - below_4g_mem_size,
-                              0x100000000ULL + above_4g_mem_size,
+                              below_4g_mem_size + below_4g_hp_mem_size,
+                              0x100000000ULL - below_4g_mem_size
+                                - below_4g_hp_mem_size,
+                              0x100000000ULL + above_4g_mem_size
+                                + above_4g_hp_mem_size,
                               (sizeof(target_phys_addr_t) == 4
                                ? 0
                                : ((uint64_t)1 << 62)),
@@ -223,6 +229,8 @@ static void pc_init1(MemoryRegion *system_memory,
         ioapic_init(gsi_state);
     }
 
+    main_memory_bus_create(object_resolve_path("i440fx", NULL));
+
     pc_register_ferr_irq(gsi[13]);
 
     pc_vga_init(isa_bus, pci_enabled ? pci_bus : NULL);
diff --git a/vl.c b/vl.c
index af1745c..2282910 100644
--- a/vl.c
+++ b/vl.c
@@ -184,6 +184,7 @@ DisplayType display_type = DT_DEFAULT;
 int display_remote = 0;
 const char* keyboard_layout = NULL;
 ram_addr_t ram_size;
+ram_addr_t ram_hp_offset;
 const char *mem_path = NULL;
 #ifdef MAP_POPULATE
 int mem_prealloc = 0; /* force preallocation of physical target memory */
