[ion] Enable building with --gc-sections

Change-Id: Ibddb03d5fc95f99954583a51c02257dfcba3a326

Makefile

@@ -19,8 +19,7 @@ ifeq ($(DEBUG),1)
 SFLAGS += -ggdb3 -DDEBUG=1 -O0
 else
 SFLAGS += -Os -fdata-sections -ffunction-sections
-#LDFLAGS += --gc-sections
-#FIXME: --gc-sections doesn't seem to be working
+LDFLAGS += --gc-sections
 endif
 
 # Language-specific flags

ion/src/device/boot/flash.ld

@@ -29,42 +29,9 @@ SECTIONS {
      *
      * We're generating the ISR vector table in code because it's very
      * convenient: using function pointers, we can easily point to the service
-     * routine for each interrupt.
-     *
-     * Last but not least, instead of pointing directly to handler functions in
-     * the ISR declaration, we take the opportunity of having a custom linker
-     * script to use meaningful names in the ISR declaration. */
+     * routine for each interrupt. */
 
-    PROVIDE(_ResetServiceRoutine = _start);
-    PROVIDE(_NMIServiceRoutine = 0);
-    PROVIDE(_HardFaultServiceRoutine = abort);
-    PROVIDE(_MemManageServiceRoutine = 0);
-    PROVIDE(_BusFaultServiceRoutine = 0);
-    PROVIDE(_UsageFaultServiceRoutine = 0);
-    PROVIDE(_SVCallServiceRoutine = 0);
-    PROVIDE(_DebugMonitorServiceRoutine = 0);
-    PROVIDE(_PendSVServiceRoutine = 0);
-    PROVIDE(_SysTickServiceRoutine = 0);
-    PROVIDE(_WWDGServiceRoutine = 0);
-    PROVIDE(_PVDServiceRoutine = 0);
-    PROVIDE(_TampStampServiceRoutine = 0);
-    PROVIDE(_RtcWakeupServiceRoutine = 0);
-    PROVIDE(_FlashServiceRoutine = 0);
-    PROVIDE(_RCCServiceRoutine = 0);
-    PROVIDE(_EXTI0ServiceRoutine = 0);
-    PROVIDE(_EXTI1ServiceRoutine = 0);
-    PROVIDE(_EXTI2ServiceRoutine = 0);
-    PROVIDE(_EXTI3ServiceRoutine = 0);
-    PROVIDE(_EXTI4ServiceRoutine = 0);
-    PROVIDE(_DMA1Stream0ServiceRoutine = 0);
-    PROVIDE(_DMA1Stream1ServiceRoutine = 0);
-    PROVIDE(_DMA1Stream2ServiceRoutine = 0);
-    PROVIDE(_DMA1Stream3ServiceRoutine = 0);
-    PROVIDE(_DMA1Stream4ServiceRoutine = 0);
-    PROVIDE(_DMA1Stream5ServiceRoutine = 0);
-    PROVIDE(_DMA1Stream6ServiceRoutine = 0);
-
-    *(.isr_vector_table)
+    KEEP(*(.isr_vector_table))
   } >FLASH
 
   .text : {

ion/src/device/boot/isr.c

@@ -1,5 +1,4 @@
-#include "isr.h"
-
+#include "rt0.h"
 extern const void * _stack_start;
 
 /* Interrupt Service Routines are void->void functions */
@@ -13,40 +12,38 @@ typedef void(*ISR)(void);
 
 #define INITIALISATION_VECTOR_SIZE 0x6B
 
-void _start();
-
 ISR InitialisationVector[INITIALISATION_VECTOR_SIZE]
   __attribute__((section(".isr_vector_table")))
   = {
-  (ISR)&_stack_start,
-  _ResetServiceRoutine,
-  _NMIServiceRoutine,
-  _HardFaultServiceRoutine,
-  _MemManageServiceRoutine,
-  _BusFaultServiceRoutine,
-  _UsageFaultServiceRoutine,
+  (ISR)&_stack_start, // Stack start
+  start, // Reset service routine,
+  0, // NMI service routine,
+  abort, // HardFault service routine,
+  0, // MemManage service routine,
+  0, // BusFault service routine,
+  0, // UsageFault service routine,
   0, 0, 0, 0, // Reserved
-  _SVCallServiceRoutine,
-  _DebugMonitorServiceRoutine,
+  0, // SVCall service routine,
+  0, // DebugMonitor service routine,
   0, // Reserved
-  _PendSVServiceRoutine,
-  _SysTickServiceRoutine,
-  _WWDGServiceRoutine,
-  _PVDServiceRoutine,
-  _TampStampServiceRoutine,
-  _RtcWakeupServiceRoutine,
-  _FlashServiceRoutine,
-  _RCCServiceRoutine,
-  _EXTI0ServiceRoutine,
-  _EXTI1ServiceRoutine,
-  _EXTI2ServiceRoutine,
-  _EXTI3ServiceRoutine,
-  _EXTI4ServiceRoutine,
-  _DMA1Stream0ServiceRoutine,
-  _DMA1Stream1ServiceRoutine,
-  _DMA1Stream2ServiceRoutine,
-  _DMA1Stream3ServiceRoutine,
-  _DMA1Stream4ServiceRoutine,
-  _DMA1Stream5ServiceRoutine,
-  _DMA1Stream6ServiceRoutine
+  0, // PendSV service routine,
+  0, // SysTick service routine
+  0, // WWDG service routine
+  0, // PVD service routine
+  0, // TampStamp service routine
+  0, // RtcWakeup service routine
+  0, // Flash service routine
+  0, // RCC service routine
+  0, // EXTI0 service routine
+  0, // EXTI1 service routine
+  0, // EXTI2 service routine
+  0, // EXTI3 service routine
+  0, // EXTI4 service routine
+  0, // DMA1Stream0 service routine
+  0, // DMA1Stream1 service routine
+  0, // DMA1Stream2 service routine
+  0, // DMA1Stream3 service routine
+  0, // DMA1Stream4 service routine
+  0, // DMA1Stream5 service routine
+  0  // DMA1Stream6 service routine
 };

ion/src/device/boot/isr.h

@@ -1,28 +0,0 @@
-void _ResetServiceRoutine();
-void _NMIServiceRoutine();
-void _HardFaultServiceRoutine();
-void _MemManageServiceRoutine();
-void _BusFaultServiceRoutine();
-void _UsageFaultServiceRoutine();
-void _SVCallServiceRoutine();
-void _DebugMonitorServiceRoutine();
-void _PendSVServiceRoutine();
-void _SysTickServiceRoutine();
-void _WWDGServiceRoutine();
-void _PVDServiceRoutine();
-void _TampStampServiceRoutine();
-void _RtcWakeupServiceRoutine();
-void _FlashServiceRoutine();
-void _RCCServiceRoutine();
-void _EXTI0ServiceRoutine();
-void _EXTI1ServiceRoutine();
-void _EXTI2ServiceRoutine();
-void _EXTI3ServiceRoutine();
-void _EXTI4ServiceRoutine();
-void _DMA1Stream0ServiceRoutine();
-void _DMA1Stream1ServiceRoutine();
-void _DMA1Stream2ServiceRoutine();
-void _DMA1Stream3ServiceRoutine();
-void _DMA1Stream4ServiceRoutine();
-void _DMA1Stream5ServiceRoutine();
-void _DMA1Stream6ServiceRoutine();

ion/src/device/boot/rt0.cpp

@@ -1,3 +1,6 @@
+extern "C" {
+#include "rt0.h"
+}
 #include <stdint.h>
 #include <string.h>
 #include <ion.h>
@@ -9,11 +12,6 @@ extern char _data_section_end_ram;
 extern char _bss_section_start_ram;
 extern char _bss_section_end_ram;
 
-extern "C" {
-  void _start();
-  void abort();
-}
-
 void abort() {
 #ifdef DEBUG
   while (1) {
@@ -23,7 +21,7 @@ void abort() {
 #endif
 }
 
-void _start() {
+void start() {
   // This is where execution starts after reset.
   // Many things are not initialized yet so the code here has to pay attention.
 

ion/src/device/boot/rt0.h

@@ -0,0 +1,7 @@
+#ifndef ION_DEVICE_BOOT_RT0_H
+#define ION_DEVICE_BOOT_RT0_H
+
+void start();
+void abort();
+
+#endif