diff --git a/exec.c b/exec.c
index 6492b0c24c..95c4356c65 100644
--- a/exec.c
+++ b/exec.c
@@ -1743,12 +1743,7 @@ void address_space_destroy_dispatch(AddressSpace *as)
 static void memory_map_init(void)
 {
     system_memory = g_malloc(sizeof(*system_memory));
-
-    assert(TARGET_PHYS_ADDR_SPACE_BITS <= 64);
-
-    memory_region_init(system_memory, NULL, "system",
-                       TARGET_PHYS_ADDR_SPACE_BITS == 64 ?
-                       UINT64_MAX : (0x1ULL << TARGET_PHYS_ADDR_SPACE_BITS));
+    memory_region_init(system_memory, NULL, "system", INT64_MAX);
     address_space_init(&address_space_memory, system_memory, "memory");
 
     system_io = g_malloc(sizeof(*system_io));
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 6cfa0446ac..486e7055a6 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1182,6 +1182,11 @@ void acpi_setup(PcGuestInfo *guest_info)
         return;
     }
 
+    if (!acpi_enabled) {
+        ACPI_BUILD_DPRINTF(3, "ACPI disabled. Bailing out.\n");
+        return;
+    }
+
     build_state = g_malloc0(sizeof *build_state);
 
     build_state->guest_info = guest_info;
diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
index bad3953fb5..edc974ece3 100644
--- a/hw/pci-host/piix.c
+++ b/hw/pci-host/piix.c
@@ -48,6 +48,7 @@ typedef struct I440FXState {
     PCIHostState parent_obj;
     PcPciInfo pci_info;
     uint64_t pci_hole64_size;
+    uint32_t short_root_bus;
 } I440FXState;
 
 #define PIIX_NUM_PIC_IRQS       16      /* i8259 * 2 */
@@ -720,13 +721,19 @@ static const TypeInfo i440fx_info = {
 static const char *i440fx_pcihost_root_bus_path(PCIHostState *host_bridge,
                                                 PCIBus *rootbus)
 {
+    I440FXState *s = I440FX_PCI_HOST_BRIDGE(host_bridge);
+
     /* For backwards compat with old device paths */
-    return "0000";
+    if (s->short_root_bus) {
+        return "0000";
+    }
+    return "0000:00";
 }
 
 static Property i440fx_props[] = {
     DEFINE_PROP_SIZE(PCI_HOST_PROP_PCI_HOLE64_SIZE, I440FXState,
                      pci_hole64_size, DEFAULT_PCI_HOLE64_SIZE),
+    DEFINE_PROP_UINT32("short_root_bus", I440FXState, short_root_bus, 0),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index b8feed1254..c043998e32 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -61,8 +61,13 @@ static void q35_host_realize(DeviceState *dev, Error **errp)
 static const char *q35_host_root_bus_path(PCIHostState *host_bridge,
                                           PCIBus *rootbus)
 {
-    /* For backwards compat with old device paths */
-    return "0000";
+    Q35PCIHost *s = Q35_HOST_DEVICE(host_bridge);
+
+     /* For backwards compat with old device paths */
+    if (s->mch.short_root_bus) {
+        return "0000";
+    }
+    return "0000:00";
 }
 
 static void q35_host_get_pci_hole_start(Object *obj, Visitor *v,
@@ -124,6 +129,7 @@ static Property mch_props[] = {
                         MCH_HOST_BRIDGE_PCIEXBAR_DEFAULT),
     DEFINE_PROP_SIZE(PCI_HOST_PROP_PCI_HOLE64_SIZE, Q35PCIHost,
                      mch.pci_hole64_size, DEFAULT_PCI_HOLE64_SIZE),
+    DEFINE_PROP_UINT32("short_root_bus", Q35PCIHost, mch.short_root_bus, 0),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index a98c8a0580..ed32059bf8 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -283,24 +283,6 @@ const char *pci_root_bus_path(PCIDevice *dev)
     return rootbus->qbus.name;
 }
 
-static uint64_t master_abort_mem_read(void *opaque, hwaddr addr, unsigned size)
-{
-   return -1ULL;
-}
-
-static void master_abort_mem_write(void *opaque, hwaddr addr, uint64_t val,
-                                   unsigned size)
-{
-}
-
-static const MemoryRegionOps master_abort_mem_ops = {
-    .read = master_abort_mem_read,
-    .write = master_abort_mem_write,
-    .endianness = DEVICE_LITTLE_ENDIAN,
-};
-
-#define MASTER_ABORT_MEM_PRIORITY INT_MIN
-
 static void pci_bus_init(PCIBus *bus, DeviceState *parent,
                          const char *name,
                          MemoryRegion *address_space_mem,
@@ -312,14 +294,6 @@ static void pci_bus_init(PCIBus *bus, DeviceState *parent,
     bus->address_space_mem = address_space_mem;
     bus->address_space_io = address_space_io;
 
-
-    memory_region_init_io(&bus->master_abort_mem, OBJECT(bus),
-                          &master_abort_mem_ops, bus, "pci-master-abort",
-                          memory_region_size(bus->address_space_mem));
-    memory_region_add_subregion_overlap(bus->address_space_mem,
-                                        0, &bus->master_abort_mem,
-                                        MASTER_ABORT_MEM_PRIORITY);
-
     /* host bridge */
     QLIST_INIT(&bus->child);
 
diff --git a/hw/ppc/ppc440_bamboo.c b/hw/ppc/ppc440_bamboo.c
index 655e49906d..67597dfb88 100644
--- a/hw/ppc/ppc440_bamboo.c
+++ b/hw/ppc/ppc440_bamboo.c
@@ -110,8 +110,9 @@ static int bamboo_load_device_tree(hwaddr addr,
     qemu_devtree_setprop_cell(fdt, "/cpus/cpu@0", "timebase-frequency",
                               tb_freq);
 
-    ret = rom_add_blob_fixed(BINARY_DEVICE_TREE_FILE, fdt, fdt_size, addr);
+    rom_add_blob_fixed(BINARY_DEVICE_TREE_FILE, fdt, fdt_size, addr);
     g_free(fdt);
+    return 0;
 
 out:
 
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 03cc0ba0f7..57e8d16180 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -260,6 +260,14 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
             .driver   = "qemu32-" TYPE_X86_CPU,\
             .property = "model",\
             .value    = stringify(3),\
+        },{\
+            .driver   = "i440FX-pcihost",\
+            .property = "short_root_bus",\
+            .value    = stringify(1),\
+        },{\
+            .driver   = "q35-pcihost",\
+            .property = "short_root_bus",\
+            .value    = stringify(1),\
         }
 
 #define PC_COMPAT_1_5 \
@@ -296,6 +304,14 @@ int e820_add_entry(uint64_t, uint64_t, uint32_t);
             .driver = TYPE_X86_CPU,\
             .property = "pmu",\
             .value = "on",\
+        },{\
+            .driver   = "i440FX-pcihost",\
+            .property = "short_root_bus",\
+            .value    = stringify(0),\
+        },{\
+            .driver   = "q35-pcihost",\
+            .property = "short_root_bus",\
+            .value    = stringify(0),\
         }
 
 #define PC_COMPAT_1_4 \
diff --git a/include/hw/loader.h b/include/hw/loader.h
index 58eca9832b..7a23d6bdc1 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -55,7 +55,7 @@ void do_info_roms(Monitor *mon, const QDict *qdict);
 #define rom_add_file_fixed(_f, _a, _i)          \
     rom_add_file(_f, NULL, _a, _i)
 #define rom_add_blob_fixed(_f, _b, _l, _a)      \
-    (rom_add_blob(_f, _b, _l, _a, NULL, NULL, NULL) ? 0 : -1)
+    rom_add_blob(_f, _b, _l, _a, NULL, NULL, NULL)
 
 #define PC_ROM_MIN_VGA     0xc0000
 #define PC_ROM_MIN_OPTION  0xc8000
diff --git a/include/hw/pci-host/q35.h b/include/hw/pci-host/q35.h
index aee91aa038..309065fa41 100644
--- a/include/hw/pci-host/q35.h
+++ b/include/hw/pci-host/q35.h
@@ -61,6 +61,7 @@ typedef struct MCHPCIState {
     ram_addr_t above_4g_mem_size;
     uint64_t pci_hole64_size;
     PcGuestInfo *guest_info;
+    uint32_t short_root_bus;
 } MCHPCIState;
 
 typedef struct Q35PCIHost {
diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
index 2ad5edbde9..9df17885ec 100644
--- a/include/hw/pci/pci_bus.h
+++ b/include/hw/pci/pci_bus.h
@@ -23,7 +23,6 @@ struct PCIBus {
     PCIDevice *parent_dev;
     MemoryRegion *address_space_mem;
     MemoryRegion *address_space_io;
-    MemoryRegion master_abort_mem;
 
     QLIST_HEAD(, PCIBus) child; /* this will be replaced by qdev later */
     QLIST_ENTRY(PCIBus) sibling;/* this will be replaced by qdev later */