If the kernel image gets too big, "cmp ebx, KERNEL_LOAD_PAGES*8 + 1"
[pintos-anon] / grading / userprog / close-stdout.exp
1 (close-stdout) begin
2 (close-stdout) end
3 close-stdout: exit(0)
4 --OR--
5 (close-stdout) begin
6 close-stdout: exit(-1)