Clarifications.

[pintos-anon] / doc / userprog.texi

diff --git a/doc/userprog.texi b/doc/userprog.texi
index 903d9c53311dcd856860b10a5749ffdbd234d3ab..9277b087f5d9d9ba30e5a90d20ab8951f9b1284d 100644 (file)
--- a/doc/userprog.texi
+++ b/doc/userprog.texi
@@ -129,7 +129,7 @@ system implementation.
 
 You need to be able to create and format simulated disks.  The
 @command{pintos} program provides this functionality with its
-@option{make-disk} command.  From the @file{filesys/build} directory,
+@option{make-disk} command.  From the @file{userprog/build} directory,
 execute @code{pintos make-disk fs.dsk 2}.  This command creates a 2 MB
 simulated disk named @file{fs.dsk}.  (It does not actually start
 Pintos.)  Then format the disk by passing the @option{-f} option to
@@ -273,9 +273,10 @@ called by user programs are prototyped in @file{lib/user/syscall.h}:
 @table @code
 @item SYS_halt
 @itemx void halt (void)
-Stops Pintos and prints out performance statistics.  Note that this
-should be seldom used, since then you lose some information about
-possible deadlock situations, etc.
+Stops Pintos by calling @func{power_off} (declared in
+@file{threads/init.h}).  Note that this should be seldom used, since
+then you lose some information about possible deadlock situations,
+etc.
 
 @item SYS_exit
 @itemx void exit (int @var{status})
@@ -299,8 +300,9 @@ process, the return value is undefined (but kernel operation must not
 be disrupted).
 
 @item SYS_create
-@itemx bool create (const char *@var{file})
-Create a new file called @var{file}.  Returns -1 if failed, 0 if OK.
+@itemx bool create (const char *@var{file}, unsigned @var{initial_size})
+Create a new file called @var{file} initially @var{initial_size} bytes
+in size.  Returns -1 if failed, 0 if OK.
 
 @item SYS_remove
 @itemx bool remove (const char *@var{file})
@@ -396,6 +398,14 @@ You may find the code for @func{thread_join} to be useful in
 implementing the join syscall, but besides that, you can use
 the original code provided for project 1.
 
+@item
+@b{All my user programs die with page faults.}
+
+This will generally happen if you haven't implemented problem 2-1
+yet.  The reason is that the basic C library for user programs tries
+to read @var{argc} and @var{argv} off the stack.  Because the stack
+isn't properly set up yet, this causes a page fault.
+
 @item
 @b{Is there a way I can disassemble user programs?}
 
@@ -417,7 +427,7 @@ is compiled as a unit.)  If you wish to port libraries to Pintos, feel
 free.
 
 @item
-@b{How do I compile new user programs? How do I make 'echo' compile?}
+@b{How do I compile new user programs?}
 
 You need to modify @file{tests/Makefile}.