expand protected mode code segment

stage_2/main.s

@@ -134,13 +134,13 @@ gdt_flat:
   dq 0
 
 ; 32-bit code segment.
-; Bytes 0x0000 - 0xffff.
+; Pages 0x0000 - 0xffff.
 .segment_code_32:
   db 0xff, 0xff, \
      0x00, 0x00, \
      0x00,       \
      10011011b,  \
-     01000000b,  \
+     11000000b,  \
      0x00
 
 ; 16-bit code segment, to use if we want to switch back to real mode.