diff --git a/boot/zephyr/boards/b_u585i_iot02a_stm32u585xx_ext_flash_app.conf b/boot/zephyr/boards/b_u585i_iot02a_stm32u585xx_ext_flash_app.conf
new file mode 100644
index 000000000..18dec9fcb
--- /dev/null
+++ b/boot/zephyr/boards/b_u585i_iot02a_stm32u585xx_ext_flash_app.conf
@@ -0,0 +1 @@
+CONFIG_STM32_MEMMAP=y
diff --git a/boot/zephyr/boards/stm32h750b_dk.conf b/boot/zephyr/boards/stm32h750b_dk.conf
new file mode 100644
index 000000000..ba48f0ae9
--- /dev/null
+++ b/boot/zephyr/boards/stm32h750b_dk.conf
@@ -0,0 +1,4 @@
+CONFIG_STM32_MEMMAP=y
+
+CONFIG_BOOT_MAX_IMG_SECTORS_AUTO=n
+CONFIG_BOOT_MAX_IMG_SECTORS=4096
diff --git a/boot/zephyr/boards/stm32h7b3i_dk_stm32h7b3xx_ext_flash_app.conf b/boot/zephyr/boards/stm32h7b3i_dk_stm32h7b3xx_ext_flash_app.conf
new file mode 100644
index 000000000..18dec9fcb
--- /dev/null
+++ b/boot/zephyr/boards/stm32h7b3i_dk_stm32h7b3xx_ext_flash_app.conf
@@ -0,0 +1 @@
+CONFIG_STM32_MEMMAP=y