Add linking step

src/startup.c

@@ -0,0 +1,34 @@
+#include <stdint.h>
+
+extern void stack_start(void);  // Defined in link.ld
+extern int main(void);
+
+void init_memory(void) {
+  // Copy .data SECTION to ram
+  extern uint32_t _data_start, _data_end, _data_addr;
+  for (uint32_t *dst = &_data_start, *src = &_data_addr; dst < &_data_end;) {
+	*dst++ = *src++;
+  }
+
+  // Initialize .bss SECTION with zeros
+  extern uint32_t _bss_start, _bss_end;
+  for (uint32_t *dst = &_bss_start; dst < &_bss_end; dst++) {
+	*dst = 0;
+  }
+}
+
+void reset(void) {
+  (void)init_memory();
+
+  main();
+
+  // Infinite loop in case main returns
+  for (;;) (void) 0;
+}
+
+// Create minimal interrupt vector table
+// 16 standard and 86 STM32F411xC/E-specific handlers
+void (*const interrupt_vector_table[16 + 86])(void) __attribute__((section(".isr_vector"))) = {
+  stack_start, // Defined in link.ld
+  reset
+};