Mention that GCC reorders statements.

[pintos-anon] / doc / debug.texi

diff --git a/doc/debug.texi b/doc/debug.texi
index d48e6392e477f7da88f33363b59abba690056da4..19270f46e46c19aa4d8897195a68622af032b913 100644 (file)
--- a/doc/debug.texi
+++ b/doc/debug.texi
@@ -16,7 +16,7 @@ introduces you to a few of them.
 @end menu
 
 @node printf
-@section @func{printf}
+@section @code{@code{printf()}}
 
 Don't underestimate the value of @func{printf}.  The way
 @func{printf} is implemented in Pintos, you can call it from
@@ -201,7 +201,15 @@ address.
 (Use a @samp{0x} prefix to specify an address in hex.)
 @end table
 
-If you notice unexplainable behavior while using @command{gdb}, there
+You might notice that @command{gdb} tends to show code being executed
+in an order different from the order in the source.  That is, the
+current statement jumps around seemingly randomly.  This is due to
+GCC's optimizer, which does tend to reorder code.  If it bothers you,
+you can turn off optimization by editing
+@file{pintos/src/Make.config}, removing @option{-O3} from the
+@code{CFLAGS} definition.
+
+If you notice other strange behavior while using @command{gdb}, there
 are three possibilities.  The first is that there is a bug in your
 modified Pintos.  The second is that there is a bug in Bochs's
 interface to @command{gdb} or in @command{gdb} itself.  The third is