Add explanatory comments to userprog tests.

[pintos-anon] / src / tests / userprog / sc-bad-arg.c

diff --git a/src/tests/userprog/sc-bad-arg.c b/src/tests/userprog/sc-bad-arg.c
index b990468db3eb031fcbdd0674dc0202d18c3fdb61..e0cad1581c6620983b15485ba59f316bdcc20f4c 100644 (file)
--- a/src/tests/userprog/sc-bad-arg.c
+++ b/src/tests/userprog/sc-bad-arg.c
@@ -1,3 +1,9 @@
+/* Sticks a system call number (SYS_exit) at the very top of the
+   stack, then invokes a system call with the stack pointer
+   (%esp) set to its address.  The process must be terminated
+   with -1 exit code because the argument to the system call
+   would be above the top of the user address space. */
+
 #include <syscall-nr.h>
 #include "tests/lib.h"
 #include "tests/main.h"