Improve debuggability by eliminating system call stub in separate

[pintos-anon] / doc / userprog.texi

diff --git a/doc/userprog.texi b/doc/userprog.texi
index e3771e4e1aaf0f79e089841fa9d6432903737973..a92697d1b4fe209cbe78b6a2d2b6965bcac41854 100644 (file)
--- a/doc/userprog.texi
+++ b/doc/userprog.texi
@@ -405,9 +405,9 @@ conditions (usually errors).
 @item SYS_exec
 @itemx pid_t exec (const char *@var{cmd_line})
 Runs the executable whose name is given in @var{cmd_line}, passing any
-given arguments, and returns the new process's program id (pid).  If
-there is an error loading this program, may return pid -1, which
-otherwise should not be a valid id number.
+given arguments, and returns the new process's program id (pid).  Must
+return pid -1, which otherwise should not be a valid program id, if
+there is an error loading this program.
 
 @item SYS_join
 @itemx int join (pid_t @var{pid})
@@ -686,7 +686,7 @@ provide a little bit of helpful code:
    Returns true if successful, false if USRC is invalid. */
 static inline bool get_user (uint8_t *dst, const uint8_t *usrc) {
   int eax;
-  asm ("movl $1f, %%eax; movb %2, %%al; movb %%al, %0; 1:"
+  asm ("mov %%eax, offset 1f; mov %%al, %2; mov %0, %%al; 1:"
        : "=m" (*dst), "=&a" (eax) : "m" (*usrc));
   return eax != 0;
 }
@@ -695,7 +695,7 @@ static inline bool get_user (uint8_t *dst, const uint8_t *usrc) {
    Returns true if successful, false if UDST is invalid. */
 static inline bool put_user (uint8_t *udst, uint8_t byte) {
   int eax;
-  asm ("movl $1f, %%eax; movb %b2, %0; 1:"
+  asm ("mov %%eax, offset 1f; mov %0, %b2; 1:"
        : "=m" (*udst), "=&a" (eax) : "r" (byte));
   return eax != 0;
 }