X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Fthreads.texi;h=bc2ccb548de6c278b0085b4bf08a098d3dcca4b5;hb=251b51f76f0594460e1cfbf2c05576fb445b861b;hp=eb59d8a4267de1629c3f3d30037faab13c4d5a8b;hpb=3c732bafbe5c72567659dfc0f397293027617c50;p=pintos-anon

diff --git a/doc/threads.texi b/doc/threads.texi
index eb59d8a..bc2ccb5 100644
--- 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
@@ -383,6 +383,33 @@ Problems 1-3 and 1-4 won't be needed for later projects.
 Problem 1-4 (MLFQS) builds on the features you implement in Problem
 1-3.  You should have Problem 1-3 fully working before you begin to
 tackle Problem 1-4.
+
+@item
+In the past, many groups divided the assignment into pieces, then each
+group member worked on his or her piece until just before the
+deadline, at which time the group reconvened to combine their code and
+submit.  @strong{This is a bad idea.  We do not recommend this
+approach.}  Groups that do this often find that two changes conflict
+with each other, requiring lots of last-minute debugging.  Some groups
+who have done this have turned in code that did not even successfully
+boot.
+
+Instead, we recommend integrating your team's changes early and often,
+using a source code control system such as CVS (@pxref{CVS}) or a
+group collaboration site such as SourceForge (@pxref{SourceForge}).
+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
@@ -500,7 +527,9 @@ 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
@@ -528,10 +557,6 @@ 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