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