Add base code

linker.ld

@@ -0,0 +1,15 @@
+ENTRY(_start)
+
+SECTIONS
+{
+    /* text section (code)*/
+    .text : { *(.text*) }
+    /* data section, initialized variables */
+    .data : { *(.data) }
+    ram_start = 0x20000000;
+    /* bss section, uninitialized variables */
+    .bss : { *(.bss*) }
+    /* stack section */
+    /* The stack is placed at the end of the RAM */
+    stack_top = 0x2001ffff;
+}