-In general, the code that you turn in must not depend on conditional
-compilation directives. Project code should be written so that all of
-the subproblems for the project function together, and it should
-compile properly without the need for any new macros to be defined.
-There are a few exceptions:
-
-@itemize @bullet
-@item
-Project 1 has a few parts that we must be able to turn on and off via
-conditional compilation. You must use the macros we specify for those
-parts.
-
-@item
-Code written for extra credit may be included conditionally. If the
-extra credit code changes the normally expected functionality of the
-code, then it @emph{must} be included conditionally, and it must not
-be enabled by default.
-@end itemize
-
-You can use @file{constants.h} in @file{pintos/src} to define macros
-for conditional compilation. We will replace the @file{constants.h}
-that you supply with one of our own when we test your code, so do not
-define anything important in it.
+Project code should be written so that all of the subproblems for the
+project function together, that is, without the need to rebuild with
+different macros defined, etc. If you do extra credit work that
+changes normal Pintos behavior so as to interfere with grading, then
+you must implement it so that it only acts that way when given a
+special command-line option of the form @option{-@var{name}}, where
+@var{name} is a name of your choice. You can add such an option by
+modifying @func{parse_options} in @file{threads/init.c}.
+
+The introduction describes additional coding style requirements
+(@pxref{Design}).