make sure g_bsp_rom_registers is not dropped by linker in cmake build.

always reserve 0x100 for option setting in linker to prevent possible bricked mcu

hw/bsp/ra/boards/portenta_c33/script/fsp.ld

@@ -173,6 +173,9 @@ SECTIONS
         . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x400;
         KEEP(*(.rom_registers*))
 
+        /* Reserving 0x100 bytes of space for ROM registers. */
+        . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x500;
+
         /* Allocate flash write-boundary-aligned
          * space for sce9 wrapped public keys for mcuboot if the module is used.
          */

hw/bsp/ra/boards/ra4m1_ek/script/fsp.ld

@@ -173,6 +173,9 @@ SECTIONS
         . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x400;
         KEEP(*(.rom_registers*))
 
+        /* Reserving 0x100 bytes of space for ROM registers. */
+        . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x500;
+
         /* Allocate flash write-boundary-aligned
          * space for sce9 wrapped public keys for mcuboot if the module is used.
          */

hw/bsp/ra/boards/ra4m3_ek/script/fsp.ld

@@ -173,6 +173,9 @@ SECTIONS
         . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x400;
         KEEP(*(.rom_registers*))
 
+        /* Reserving 0x100 bytes of space for ROM registers. */
+        . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x500;
+
         /* Allocate flash write-boundary-aligned
          * space for sce9 wrapped public keys for mcuboot if the module is used.
          */

hw/bsp/ra/boards/ra6m1_ek/script/fsp.ld

@@ -173,6 +173,9 @@ SECTIONS
         . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x400;
         KEEP(*(.rom_registers*))
 
+        /* Reserving 0x100 bytes of space for ROM registers. */
+        . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x500;
+
         /* Allocate flash write-boundary-aligned
          * space for sce9 wrapped public keys for mcuboot if the module is used.
          */

hw/bsp/ra/boards/ra6m5_ek/script/fsp.ld

@@ -173,6 +173,9 @@ SECTIONS
         . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x400;
         KEEP(*(.rom_registers*))
 
+        /* Reserving 0x100 bytes of space for ROM registers. */
+        . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x500;
+
         /* Allocate flash write-boundary-aligned
          * space for sce9 wrapped public keys for mcuboot if the module is used.
          */

hw/bsp/ra/boards/ra8m1_ek/script/fsp.ld

@@ -177,6 +177,9 @@ SECTIONS
         . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x400;
         KEEP(*(.rom_registers*))
 
+        /* Reserving 0x100 bytes of space for ROM registers. */
+        . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x500;
+
         /* Allocate flash write-boundary-aligned
          * space for sce9 wrapped public keys for mcuboot if the module is used.
          */

hw/bsp/ra/boards/uno_r4/script/fsp.ld

@@ -173,6 +173,9 @@ SECTIONS
         . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x400;
         KEEP(*(.rom_registers*))
 
+        /* Reserving 0x100 bytes of space for ROM registers. */
+        . = OPTION_SETTING_LENGTH > 0 ? . : __ROM_Start + 0x500;
+
         /* Allocate flash write-boundary-aligned
          * space for sce9 wrapped public keys for mcuboot if the module is used.
          */

hw/bsp/ra/family.cmake

@@ -54,7 +54,6 @@ function(add_board_target BOARD_TARGET)
       ${FSP_RA}/src/bsp/mcu/all/bsp_io.c
       ${FSP_RA}/src/bsp/mcu/all/bsp_irq.c
       ${FSP_RA}/src/bsp/mcu/all/bsp_register_protection.c
-      ${FSP_RA}/src/bsp/mcu/all/bsp_rom_registers.c
       ${FSP_RA}/src/bsp/mcu/all/bsp_sbrk.c
       ${FSP_RA}/src/bsp/mcu/all/bsp_security.c
       ${FSP_RA}/src/r_ioport/r_ioport.c
@@ -125,12 +124,17 @@ function(family_configure_example TARGET RTOS)
     # BSP
     ${CMAKE_CURRENT_FUNCTION_LIST_DIR}/family.c
     ${CMAKE_CURRENT_FUNCTION_LIST_DIR}/../board.c
+    # Explicitly added bsp_rom_registers here, otherwise MCU can be bricked if g_bsp_rom_registers is dropped by linker
+    ${FSP_RA}/src/bsp/mcu/all/bsp_rom_registers.c
     )
   target_include_directories(${TARGET} PUBLIC
     # family, hw, board
     ${CMAKE_CURRENT_FUNCTION_LIST_DIR}
     ${CMAKE_CURRENT_FUNCTION_LIST_DIR}/../../
     )
+  target_compile_options(${TARGET} PUBLIC
+    -Wno-error=undef
+    )
 
 #  # RA has custom freertos port
 #  if (NOT TARGET freertos_kernel_port)