AP_HAL_ChibiOS: add define for bootloader to find first DMA SAFE Memory

libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py

@@ -1132,6 +1132,13 @@ def write_mcu_config(self, f):
         f.write('#define HAL_CC_MEMORY_REGIONS %s\n' % ', '.join(cc_regions))
         f.write('#define HAL_MEMORY_TOTAL_KB %u\n' % (total_memory/1024))
 
+        if self.is_bootloader_fw() and not (ram_map[0][2] & 0x01):
+            # if first memory region is DMA safe then nothing to do
+            for (address, size, flags) in ram_map:
+                if flags & 0x01:
+                    f.write('#define HAL_DMA_SAFE_MEM_START 0x%x' % address)
+                    break
+
         f.write('\n// CPU serial number (12 bytes)\n')
         udid_start = self.get_mcu_config('UDID_START')
         if udid_start is None: