Get rid of THREAD_JOIN_IMPLEMENTED by adding thread_join() stub.

[pintos-anon] / doc / threads.texi

diff --git a/doc/threads.texi b/doc/threads.texi
index 8e6e38de64de1b93777a2e5f3770c094d321c612..1905707ffa09a631d2a7114febf6472438b52d93 100644 (file)
--- a/doc/threads.texi
+++ b/doc/threads.texi
@@ -157,9 +157,9 @@ the kernel.
 Basic interrupt handling and functions for turning interrupts on and
 off.
 
-@item intr-stubs.pl
+@item intr-stubs.S
 @itemx intr-stubs.h
-A Perl program that outputs assembly for low-level interrupt handling.
+Assembly code for low-level interrupt handling.
 
 @item synch.c
 @itemx synch.h
@@ -401,6 +401,15 @@ This is less likely to produce surprises, because everyone can see
 everyone else's code as it is written, instead of just when it is
 finished.  These systems also make it possible to review changes and,
 when a change introduces a bug, drop back to working versions of code.
+
+@item
+You should expect to run into bugs that you simply don't understand
+while working on this and subsequent projects.  When you do, go back
+and reread the appendix on debugging tools, which is filled with
+useful debugging tips that should help you to get back up to speed
+(@pxref{Debugging Tools}).  Be sure to read the section on backtraces
+(@pxref{Backtraces}), which will help you to get the most out of every
+kernel panic or assertion failure.
 @end itemize
 
 @node Problem 1-1 Alarm Clock
@@ -478,7 +487,10 @@ exited at the time of the later joins.  Thus, joins on T after the
 first should return immediately.
 
 Calling @func{thread_join} on an thread that is not the caller's
-child should cause the caller to return immediately.
+child should cause the caller to return immediately.  For this purpose,
+children are not inherited, that is, if @var{A} has child @var{B} and
+@var{B} has child @var{C}, then @var{A} always returns immediately
+should it try to join @var{C}, even if @var{B} is dead.
 
 Consider all the ways a join can occur: nested joins (@var{A} joins
 @var{B}, then @var{B} joins @var{C}), multiple joins (@var{A} joins
@@ -486,15 +498,10 @@ Consider all the ways a join can occur: nested joins (@var{A} joins
 if @func{thread_join} is called on a thread that has not yet been
 scheduled for the first time?  You should handle all of these cases.
 Write test code that demonstrates the cases your join works for.
-Don't overdo the output volume, please!
 
 Be careful to program this function correctly.  You will need its
 functionality for project 2.
 
-Once you've implemented @func{thread_join}, define
-@code{THREAD_JOIN_IMPLEMENTED} in @file{constants.h}.
-@xref{Conditional Compilation}, for more information.
-
 @node Problem 1-3 Priority Scheduling
 @section Problem 1-3: Priority Scheduling
 
@@ -518,7 +525,9 @@ than the currently running thread, the current thread should
 immediately yield the processor to the new thread.  Similarly, when
 threads are waiting for a lock, semaphore or condition variable, the
 highest priority waiting thread should be woken up first.  A thread
-may set its priority at any time.
+may raise or lower its own priority at any time, but lowering its
+priority such that it no longer has the highest priority must cause it
+to immediately yield the CPU.
 
 One issue with priority scheduling is ``priority inversion'': if a
 high priority thread needs to wait for a low priority thread (for
@@ -546,10 +555,6 @@ implement this fix for semaphores, condition variables, or joins,
 although you are welcome to do so.  However, you do need to implement
 priority scheduling in all cases.
 
-You may assume a static priority for priority donation, that is, it is
-not necessary to ``re-donate'' a thread's priority if it changes
-(although you are free to do so).
-
 @node Problem 1-4 Advanced Scheduler
 @section Problem 1-4: Advanced Scheduler