need --trace-children when self-hosting



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@5064 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/README_DEVELOPERS b/README_DEVELOPERS
index 798c47c..f05b848 100644
--- a/README_DEVELOPERS
+++ b/README_DEVELOPERS
@@ -66,18 +66,20 @@
 
 (4) Choose a very simple program (date) and try
 
-    outer/.../bin/valgrind --weird-hacks=enable-outer   \
+    outer/.../bin/valgrind --weird-hacks=enable-outer --trace-children=yes  \
        --tool=cachegrind -v inner/.../bin/valgrind --tool=none -v prog
 
-It's fragile, confusing and slow, but it does work well enough for
-you to get some useful performance data.  The inner Valgrind has most of
-its output (ie. those lines beginning with "==<pid>==") prefixed with a
-'>', which helps a lot.
+If you omit the --trace-children=yes, you'll only valgrind inner's launcher
+program, not its stage2.  The whole thing is fragile, confusing and slow,
+but it does work well enough for you to get some useful performance data.
+The inner Valgrind has most of its output (ie. those lines beginning with
+"==<pid>==") prefixed with a '>', which helps a lot.
 
 At the time of writing the allocator is not annotated with client requests
 so Memcheck is not as useful as it could be.  It also has not been tested
 much, so don't be surprised if you hit problems.
 
+
 Printing out problematic blocks
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 If you want to print out a disassembly of a particular block that