diff --git a/boot/zephyr/boards/stm32h7s78_dk.conf b/boot/zephyr/boards/stm32h7s78_dk.conf
deleted file mode 100644
index 93013ed9a1..0000000000
--- a/boot/zephyr/boards/stm32h7s78_dk.conf
+++ /dev/null
@@ -1,4 +0,0 @@
-CONFIG_BOOT_DIRECT_XIP=y
-CONFIG_STM32_MEMMAP=y
-CONFIG_BOOT_MAX_IMG_SECTORS_AUTO=n
-CONFIG_BOOT_MAX_IMG_SECTORS=4096
diff --git a/boot/zephyr/socs/stm32h7s7xx_ext_flash_app.conf b/boot/zephyr/socs/stm32h7s7xx_ext_flash_app.conf
new file mode 100644
index 0000000000..2e008f3292
--- /dev/null
+++ b/boot/zephyr/socs/stm32h7s7xx_ext_flash_app.conf
@@ -0,0 +1 @@
+CONFIG_STM32_MEMMAP=y
\ No newline at end of file
diff --git a/boot/zephyr/socs/stm32h7s7xx_ext_flash_app.overlay b/boot/zephyr/socs/stm32h7s7xx_ext_flash_app.overlay
new file mode 100644
index 0000000000..0d8b3f5f11
--- /dev/null
+++ b/boot/zephyr/socs/stm32h7s7xx_ext_flash_app.overlay
@@ -0,0 +1,7 @@
+/ {
+	chosen {
+		zephyr,flash = &flash0;
+		zephyr,flash-controller = &flash;
+		zephyr,code-partition = &boot_partition;
+	};
+};