diff --git a/hw/core/loader.c b/hw/core/loader.c
index 7527fd3036..d3f8501dc7 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -712,12 +712,22 @@ static void rom_insert(Rom *rom)
     QTAILQ_INSERT_TAIL(&roms, rom, next);
 }
 
+static void fw_cfg_resized(const char *id, uint64_t length, void *host)
+{
+    if (fw_cfg) {
+        fw_cfg_modify_file(fw_cfg, id + strlen("/rom@"), host, length);
+    }
+}
+
 static void *rom_set_mr(Rom *rom, Object *owner, const char *name)
 {
     void *data;
 
     rom->mr = g_malloc(sizeof(*rom->mr));
-    memory_region_init_ram(rom->mr, owner, name, rom->datasize, &error_abort);
+    memory_region_init_resizeable_ram(rom->mr, owner, name,
+                                      rom->datasize, rom->romsize,
+                                      fw_cfg_resized,
+                                      &error_abort);
     memory_region_set_readonly(rom->mr, true);
     vmstate_register_ram_global(rom->mr);
 
@@ -812,7 +822,7 @@ err:
 }
 
 ram_addr_t rom_add_blob(const char *name, const void *blob, size_t len,
-                   hwaddr addr, const char *fw_file_name,
+                   size_t max_len, hwaddr addr, const char *fw_file_name,
                    FWCfgReadCallback fw_callback, void *callback_opaque)
 {
     Rom *rom;
@@ -821,7 +831,7 @@ ram_addr_t rom_add_blob(const char *name, const void *blob, size_t len,
     rom           = g_malloc0(sizeof(*rom));
     rom->name     = g_strdup(name);
     rom->addr     = addr;
-    rom->romsize  = len;
+    rom->romsize  = max_len ? max_len : len;
     rom->datasize = len;
     rom->data     = g_malloc0(rom->datasize);
     memcpy(rom->data, blob, len);
@@ -841,7 +851,7 @@ ram_addr_t rom_add_blob(const char *name, const void *blob, size_t len,
 
         fw_cfg_add_file_callback(fw_cfg, fw_file_name,
                                  fw_callback, callback_opaque,
-                                 data, rom->romsize);
+                                 data, rom->datasize);
     }
     return ret;
 }
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index a4d0c0c8bf..6a2e9c52bc 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -68,6 +68,9 @@
 
 #define ACPI_BUILD_TABLE_SIZE             0x20000
 
+/* Reserve RAM space for tables: add another order of magnitude. */
+#define ACPI_BUILD_TABLE_MAX_SIZE         0x200000
+
 /* #define DEBUG_ACPI_BUILD */
 #ifdef DEBUG_ACPI_BUILD
 #define ACPI_BUILD_DPRINTF(fmt, ...)        \
@@ -1718,6 +1721,11 @@ static void acpi_build_update(void *build_opaque, uint32_t offset)
     acpi_build(build_state->guest_info, &tables);
 
     assert(acpi_data_len(tables.table_data) == build_state->table_size);
+
+    /* Make sure RAM size is correct - in case it got changed by migration */
+    qemu_ram_resize(build_state->table_ram, build_state->table_size,
+                    &error_abort);
+
     memcpy(qemu_get_ram_ptr(build_state->table_ram), tables.table_data->data,
            build_state->table_size);
 
@@ -1734,10 +1742,10 @@ static void acpi_build_reset(void *build_opaque)
 }
 
 static ram_addr_t acpi_add_rom_blob(AcpiBuildState *build_state, GArray *blob,
-                               const char *name)
+                               const char *name, uint64_t max_size)
 {
-    return rom_add_blob(name, blob->data, acpi_data_len(blob), -1, name,
-                        acpi_build_update, build_state);
+    return rom_add_blob(name, blob->data, acpi_data_len(blob), max_size, -1,
+                        name, acpi_build_update, build_state);
 }
 
 static const VMStateDescription vmstate_acpi_build = {
@@ -1781,11 +1789,12 @@ void acpi_setup(PcGuestInfo *guest_info)
 
     /* Now expose it all to Guest */
     build_state->table_ram = acpi_add_rom_blob(build_state, tables.table_data,
-                                               ACPI_BUILD_TABLE_FILE);
+                                               ACPI_BUILD_TABLE_FILE,
+                                               ACPI_BUILD_TABLE_MAX_SIZE);
     assert(build_state->table_ram != RAM_ADDR_MAX);
     build_state->table_size = acpi_data_len(tables.table_data);
 
-    acpi_add_rom_blob(NULL, tables.linker, "etc/table-loader");
+    acpi_add_rom_blob(NULL, tables.linker, "etc/table-loader", 0);
 
     fw_cfg_add_file(guest_info->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
                     tables.tcpalog->data, acpi_data_len(tables.tcpalog));
diff --git a/hw/lm32/lm32_hwsetup.h b/hw/lm32/lm32_hwsetup.h
index 9fd5e697a7..838754d5d8 100644
--- a/hw/lm32/lm32_hwsetup.h
+++ b/hw/lm32/lm32_hwsetup.h
@@ -73,7 +73,8 @@ static inline void hwsetup_free(HWSetup *hw)
 static inline void hwsetup_create_rom(HWSetup *hw,
         hwaddr base)
 {
-    rom_add_blob("hwsetup", hw->data, TARGET_PAGE_SIZE, base, NULL, NULL, NULL);
+    rom_add_blob("hwsetup", hw->data, TARGET_PAGE_SIZE,
+                 TARGET_PAGE_SIZE, base, NULL, NULL, NULL);
 }
 
 static inline void hwsetup_add_u8(HWSetup *hw, uint8_t u)
diff --git a/include/hw/loader.h b/include/hw/loader.h
index 64816395dc..1d761088ce 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -60,7 +60,7 @@ int rom_add_file(const char *file, const char *fw_dir,
                  hwaddr addr, int32_t bootindex,
                  bool option_rom);
 ram_addr_t rom_add_blob(const char *name, const void *blob, size_t len,
-                   hwaddr addr, const char *fw_file_name,
+                   size_t max_len, hwaddr addr, const char *fw_file_name,
                    FWCfgReadCallback fw_callback, void *callback_opaque);
 int rom_add_elf_program(const char *name, void *data, size_t datasize,
                         size_t romsize, hwaddr addr);
@@ -74,7 +74,7 @@ void do_info_roms(Monitor *mon, const QDict *qdict);
 #define rom_add_file_fixed(_f, _a, _i)          \
     rom_add_file(_f, NULL, _a, _i, false)
 #define rom_add_blob_fixed(_f, _b, _l, _a)      \
-    rom_add_blob(_f, _b, _l, _a, NULL, NULL, NULL)
+    rom_add_blob(_f, _b, _l, _l, _a, NULL, NULL, NULL)
 
 #define PC_ROM_MIN_VGA     0xc0000
 #define PC_ROM_MIN_OPTION  0xc8000