README_DEVELOPERS: Debugging a tool needs "--tool=..."

Otherwise the function redirections / client requests seem
to get confused. Symptoms are error messages such as
--3031-- VG_USERREQ__CLIENT_CALL1: func=0x0

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12852

diff --git a/README_DEVELOPERS b/README_DEVELOPERS
index de8082ba05c5ae4bbc66c5b0195ca0bc41ab275a..2201fd63c8bd4c1705d50002e17bcef03288264b 100644 (file)
--- a/README_DEVELOPERS
+++ b/README_DEVELOPERS
@@ -111,9 +111,10 @@ without too much problem by following these steps:
 
     (gdb) b vgPlain_do_exec
 
-(5) Run the tool with required options:
+(5) Run the tool with required options (the --tool option is required
+    for correct setup), e.g.
 
-    (gdb) run pwd
+    (gdb) run --tool=lackey pwd
 
 Steps (1)--(3) can be put in a .gdbinit file, but any directory names must
 be fully expanded (ie. not an environment variable).