If you run with -v, you currently get two kinds of messages. Some of them are useful to the user, eg. lists of all errors reported, lists of suppressions used. But most of them are debugging messages only useful to Valgrind developers. Furthermore, we also have the -d option which prints only debugging messages. We should move all debugging messages out of -v, into -d, so that users can run -v and only get info that is useful to them. A consequence of this is that, because -d printing is implemented in a more low-level way than -v printing, debugging messages can only print to stderr. But this doesn't seem like much of a problem.