diff --git a/ports/stm32/boards/ARDUINO_GIGA/mpconfigboard.h b/ports/stm32/boards/ARDUINO_GIGA/mpconfigboard.h
index 440326035311..98ccac460ab0 100644
--- a/ports/stm32/boards/ARDUINO_GIGA/mpconfigboard.h
+++ b/ports/stm32/boards/ARDUINO_GIGA/mpconfigboard.h
@@ -7,6 +7,7 @@
 #define MICROPY_HW_BOARD_NAME       "Arduino GIGA R1 WiFi"
 #define MICROPY_HW_MCU_NAME         "STM32H747"
 #define MICROPY_HW_FLASH_FS_LABEL   "GIGA R1 WiFi"
+#define MICROPY_VFS_ROM             (1)
 
 // Network config
 #define MICROPY_PY_NETWORK_HOSTNAME_DEFAULT "mpy-giga-r1-wifi"
@@ -125,8 +126,8 @@ void GIGA_board_low_power(int mode);
 // QSPI flash #1 for storage
 #define MICROPY_HW_QSPI_PRESCALER           (2) // 100MHz
 #define MICROPY_HW_QSPIFLASH_SIZE_BITS_LOG2 (27)
-// Reserve 1MiB at the end for compatibility with alternate firmware that places WiFi blob here.
-#define MICROPY_HW_SPIFLASH_SIZE_BITS       (120 * 1024 * 1024)
+// Reserve 4MiB for romfs and 1MiB at for WiFi/BT firmware.
+#define MICROPY_HW_SPIFLASH_SIZE_BITS       (88 * 1024 * 1024)
 #define MICROPY_HW_QSPIFLASH_CS             (pyb_pin_QSPI2_CS)
 #define MICROPY_HW_QSPIFLASH_SCK            (pyb_pin_QSPI2_CLK)
 #define MICROPY_HW_QSPIFLASH_IO0            (pyb_pin_QSPI2_D0)
diff --git a/ports/stm32/boards/ARDUINO_NICLA_VISION/mpconfigboard.h b/ports/stm32/boards/ARDUINO_NICLA_VISION/mpconfigboard.h
index 9e21cd0f1d9e..382f4f590d89 100644
--- a/ports/stm32/boards/ARDUINO_NICLA_VISION/mpconfigboard.h
+++ b/ports/stm32/boards/ARDUINO_NICLA_VISION/mpconfigboard.h
@@ -7,6 +7,7 @@
 #define MICROPY_HW_BOARD_NAME       "Arduino Nicla Vision"
 #define MICROPY_HW_MCU_NAME         "STM32H747"
 #define MICROPY_HW_FLASH_FS_LABEL   "Nicla Vision"
+#define MICROPY_VFS_ROM             (1)
 
 // Network config
 #define MICROPY_PY_NETWORK_HOSTNAME_DEFAULT "mpy-nicla-vision"
@@ -130,8 +131,8 @@ void NICLAV_board_osc_enable(int enable);
 // QSPI flash for storage
 #define MICROPY_HW_QSPI_PRESCALER           (2) // 100MHz
 #define MICROPY_HW_QSPIFLASH_SIZE_BITS_LOG2 (27)
-// Reserve 1MiB at the end for compatibility with alternate firmware that places WiFi blob here.
-#define MICROPY_HW_SPIFLASH_SIZE_BITS       (120 * 1024 * 1024)
+// Reserve 4MiB for romfs and 1MiB at for WiFi/BT firmware.
+#define MICROPY_HW_SPIFLASH_SIZE_BITS       (88 * 1024 * 1024)
 #define MICROPY_HW_QSPIFLASH_CS             (pyb_pin_QSPI2_CS)
 #define MICROPY_HW_QSPIFLASH_SCK            (pyb_pin_QSPI2_CLK)
 #define MICROPY_HW_QSPIFLASH_IO0            (pyb_pin_QSPI2_D0)
diff --git a/ports/stm32/boards/ARDUINO_PORTENTA_H7/mpconfigboard.h b/ports/stm32/boards/ARDUINO_PORTENTA_H7/mpconfigboard.h
index 27eb8c00243f..e40a2856e9e4 100644
--- a/ports/stm32/boards/ARDUINO_PORTENTA_H7/mpconfigboard.h
+++ b/ports/stm32/boards/ARDUINO_PORTENTA_H7/mpconfigboard.h
@@ -7,6 +7,7 @@
 #define MICROPY_HW_BOARD_NAME       "Arduino Portenta H7"
 #define MICROPY_HW_MCU_NAME         "STM32H747"
 #define MICROPY_HW_FLASH_FS_LABEL   "Portenta H7"
+#define MICROPY_VFS_ROM             (1)
 
 // Network config
 #define MICROPY_PY_NETWORK_HOSTNAME_DEFAULT "mpy-portenta-h7"
@@ -129,8 +130,8 @@ void PORTENTA_board_osc_enable(int enable);
 // QSPI flash #1 for storage
 #define MICROPY_HW_QSPI_PRESCALER           (2) // 100MHz
 #define MICROPY_HW_QSPIFLASH_SIZE_BITS_LOG2 (27)
-// Reserve 1MiB at the end for compatibility with alternate firmware that places WiFi blob here.
-#define MICROPY_HW_SPIFLASH_SIZE_BITS       (120 * 1024 * 1024)
+// Reserve 4MiB for romfs and 1MiB at for WiFi/BT firmware.
+#define MICROPY_HW_SPIFLASH_SIZE_BITS       (88 * 1024 * 1024)
 #define MICROPY_HW_QSPIFLASH_CS             (pyb_pin_QSPI2_CS)
 #define MICROPY_HW_QSPIFLASH_SCK            (pyb_pin_QSPI2_CLK)
 #define MICROPY_HW_QSPIFLASH_IO0            (pyb_pin_QSPI2_D0)
diff --git a/ports/stm32/boards/OPENMV2/mpconfigboard.h b/ports/stm32/boards/OPENMV2/mpconfigboard.h
index 37d0708f413e..4e66bec35883 100644
--- a/ports/stm32/boards/OPENMV2/mpconfigboard.h
+++ b/ports/stm32/boards/OPENMV2/mpconfigboard.h
@@ -2,6 +2,7 @@
 #define MICROPY_HW_MCU_NAME         "STM32F427"
 #define MICROPY_PY_SYS_PLATFORM     "OpenMV2"
 #define MICROPY_HW_FLASH_FS_LABEL   "OPENMV"
+#define MICROPY_VFS_ROM             (1)
 
 #define MICROPY_OBJ_REPR            (MICROPY_OBJ_REPR_C)
 #define UINT_FMT                    "%u"
diff --git a/ports/stm32/boards/OPENMV3/mpconfigboard.h b/ports/stm32/boards/OPENMV3/mpconfigboard.h
index 389d8ec6a8e9..adb2703b8e9e 100644
--- a/ports/stm32/boards/OPENMV3/mpconfigboard.h
+++ b/ports/stm32/boards/OPENMV3/mpconfigboard.h
@@ -2,6 +2,7 @@
 #define MICROPY_HW_MCU_NAME         "STM32F765"
 #define MICROPY_PY_SYS_PLATFORM     "OpenMV3-M7"
 #define MICROPY_HW_FLASH_FS_LABEL   "OPENMV"
+#define MICROPY_VFS_ROM             (1)
 
 #define MICROPY_OBJ_REPR            (MICROPY_OBJ_REPR_C)
 #define UINT_FMT                    "%u"
diff --git a/ports/stm32/boards/OPENMV4/mpconfigboard.h b/ports/stm32/boards/OPENMV4/mpconfigboard.h
index 464f65034f01..f0ca7f198045 100644
--- a/ports/stm32/boards/OPENMV4/mpconfigboard.h
+++ b/ports/stm32/boards/OPENMV4/mpconfigboard.h
@@ -2,6 +2,7 @@
 #define MICROPY_HW_MCU_NAME         "STM32H743"
 #define MICROPY_PY_SYS_PLATFORM     "OpenMV4-H7"
 #define MICROPY_HW_FLASH_FS_LABEL   "OPENMV"
+#define MICROPY_VFS_ROM             (1)
 
 #define MICROPY_OBJ_REPR            (MICROPY_OBJ_REPR_C)
 #define UINT_FMT                    "%u"
diff --git a/ports/stm32/boards/OPENMV4P/mpconfigboard.h b/ports/stm32/boards/OPENMV4P/mpconfigboard.h
index 38c7d20624ec..1fc2c1e4879a 100644
--- a/ports/stm32/boards/OPENMV4P/mpconfigboard.h
+++ b/ports/stm32/boards/OPENMV4P/mpconfigboard.h
@@ -2,6 +2,7 @@
 #define MICROPY_HW_MCU_NAME         "STM32H743"
 #define MICROPY_PY_SYS_PLATFORM     "OpenMV4P-H7"
 #define MICROPY_HW_FLASH_FS_LABEL   "OPENMV"
+#define MICROPY_VFS_ROM             (1)
 
 #define MICROPY_OBJ_REPR            (MICROPY_OBJ_REPR_C)
 #define UINT_FMT                    "%u"
@@ -133,7 +134,7 @@ extern const struct _mp_obj_type_t mod_network_nic_type_winc;
 
 // QSPI Flash 256MBits
 #define MICROPY_HW_QSPI_PRESCALER           (2) // F_CLK = F_AHB/2 (100MHz)
-#define MICROPY_HW_SPIFLASH_SIZE_BITS       (256 * 1024 * 1024)
+#define MICROPY_HW_SPIFLASH_SIZE_BITS       (192 * 1024 * 1024)
 #define MICROPY_HW_QSPIFLASH_SIZE_BITS_LOG2 (28)
 #define MICROPY_HW_QSPIFLASH_CS             (pyb_pin_QSPIFLASH_CS)
 #define MICROPY_HW_QSPIFLASH_SCK            (pyb_pin_QSPIFLASH_SCK)
diff --git a/ports/stm32/boards/OPENMVPT/mpconfigboard.h b/ports/stm32/boards/OPENMVPT/mpconfigboard.h
index 797e92338780..e0ceac101889 100644
--- a/ports/stm32/boards/OPENMVPT/mpconfigboard.h
+++ b/ports/stm32/boards/OPENMVPT/mpconfigboard.h
@@ -2,6 +2,7 @@
 #define MICROPY_HW_MCU_NAME         "STM32H743"
 #define MICROPY_PY_SYS_PLATFORM     "OpenMVPureThermal"
 #define MICROPY_HW_FLASH_FS_LABEL   "OPENMV"
+#define MICROPY_VFS_ROM             (1)
 
 #define MICROPY_OBJ_REPR            (MICROPY_OBJ_REPR_C)
 #define UINT_FMT                    "%u"
@@ -145,7 +146,7 @@ extern const struct _mp_obj_type_t mod_network_nic_type_winc;
 
 // QSPI Flash 256MBits
 #define MICROPY_HW_QSPI_PRESCALER           (2) // F_CLK = F_AHB/2 (100MHz)
-#define MICROPY_HW_SPIFLASH_SIZE_BITS       (256 * 1024 * 1024)
+#define MICROPY_HW_SPIFLASH_SIZE_BITS       (192 * 1024 * 1024)
 #define MICROPY_HW_QSPIFLASH_SIZE_BITS_LOG2 (28)
 #define MICROPY_HW_QSPIFLASH_CS             (pin_G6)
 #define MICROPY_HW_QSPIFLASH_SCK            (pin_F10)