Merge pull request #12144 from hugueskamba/hk-nrf52840-two-mem-region-model

NRF52840: Use 2 region memory model for the ARM toolchain

Author: 0xc0170

targets/TARGET_NORDIC/TARGET_NRF5x/TARGET_NRF52/TARGET_MCU_NRF52840/device/TOOLCHAIN_ARM_STD/nRF52840.sct

@@ -25,6 +25,9 @@
 #define MBED_RAM1_START (MBED_CRASH_REPORT_RAM_START + MBED_CRASH_REPORT_RAM_SIZE)
 #define MBED_RAM1_SIZE  (MBED_RAM_SIZE - (MBED_RAM0_SIZE + MBED_CRASH_REPORT_RAM_SIZE))
 
+
+#define RAM_FIXED_SIZE   (MBED_BOOT_STACK_SIZE+MBED_RAM0_SIZE+MBED_CRASH_REPORT_RAM_SIZE)
+
 LR_IROM1 MBED_APP_START MBED_APP_SIZE {
   ER_IROM1 MBED_APP_START MBED_APP_SIZE {
    *.o (RESET, +First)
@@ -39,6 +42,8 @@ LR_IROM1 MBED_APP_START MBED_APP_SIZE {
   RW_IRAM1 MBED_RAM1_START MBED_RAM1_SIZE {
    .ANY (+RW +ZI)
   }
+  ARM_LIB_HEAP  AlignExpr(+0, 16)  EMPTY  (MBED_RAM_SIZE-RAM_FIXED_SIZE+MBED_RAM_START-AlignExpr(ImageLimit(RW_IRAM1), 16))  {
+  }
   ARM_LIB_STACK MBED_RAM1_START+MBED_RAM1_SIZE EMPTY -Stack_Size { ; Stack region growing down
   }
 }