Add a flash linker script. Push the example into flash.

Makefile

@@ -8,7 +8,10 @@ CFLAGS = -mcpu=cortex-m0 -mthumb -O -nostdlib -std=gnu99 -fno-toplevel-reorder
 all: first.bin
 
 first.elf: first.o
-	$(CC) $(CFLAGS) -T first.ld -o $@ $<
+	$(CC) $(CFLAGS) -T flash.ld -o $@ $<
 
 %.bin: %.elf
 	$(OBJCOPY) -Obinary $< $@
+
+clean:
+	rm -f *.o *.elf *.bin

first.c

@@ -15,8 +15,12 @@ typedef volatile uint32_t REG32;
 #define GPIO_GPIO2DATA                            (*(pREG32 (0x50023FFC)))    // Port data register
 #define GPIO_GPIO2DIR                             (*(pREG32 (0x50028000)))    // Data direction register
 
+#define RAM_START  0x10000000
+#define RAM_SIZE   8192
+
 void pwm(int level, int top);
 
+__attribute__((naked))
 void start(void)
 {
   GPIO_GPIO2DIR = 0xFFFF;
@@ -74,3 +78,15 @@ void startx(void)
 	}
     }
 }
+
+__attribute__((section(".vectors")))
+const void * vectors[] = {
+  (void *)(RAM_START + RAM_SIZE - 64),
+  start,
+  0,
+  0,
+  0,
+  0,
+  0,
+  0,
+};

first.ld

@@ -4,6 +4,7 @@ SECTIONS
      {
        . = 0x10000400;
        .text : { *(.text) }
+       .vectors : { *(.vectors) }
        .data : { *(.data) }
        .bss : { *(.bss) }
      }