* fix some bugs
diff --git a/bootstub.c b/bootstub.c
index 6f894d3..27fe646 100644
--- a/bootstub.c
+++ b/bootstub.c
@@ -75,10 +75,14 @@
 
 int main(void)
 {
+	*(char*)0xb8000='A';
 	setup_idt();
+	*(char*)0xb8000='B';
 	setup_gdt();
+	*(char*)0xb8000='C';
 	setup_boot_params((struct boot_params *)BOOT_PARAMS_OFFSET, 
 		(struct setup_header*)SETUP_HEADER_OFFSET);
+	*(char*)0xb8000='D';
 	return get_32bit_entry((unsigned char *)BZIMAGE_OFFSET);
 }