We have provided you a user-level function for each system call in
@file{lib/user/syscall.c}. These provide a way for user processes to
-invoke each system call from a C program. Each of them calls an
-assembly language routine in @file{lib/user/syscall-stub.S}, which in
-turn invokes the system call interrupt and returns.
+invoke each system call from a C program. Each uses a little inline
+assembly code to invoke the system call and (if appropriate) returns the
+system call's return value.
When you're done with this part, and forevermore, Pintos should be
bulletproof. Nothing that a user program can do should ever cause the