Increase stack size to 16k

src/arch/x86_64/boot.asm

@@ -151,7 +151,7 @@ p3_table:
 p2_table:
     resb 4096
 stack_bottom:
-    resb 64
+    resb 4096 * 4
 stack_top:
 
 section .rodata

src/lib.rs

@@ -13,8 +13,6 @@ mod vga_buffer;
 
 #[no_mangle]
 pub extern fn rust_main() {
-    // ATTENTION: we have a very small stack and no guard page
-
     vga_buffer::clear_screen();
     println!("Hello World{}", "!");