Redefinition calls the verifier passing true for should_verify_class.

      RedefineVerifyMark rvm(the_class, scratch_class, state);
      Verifier::verify(scratch_class, true, THREAD);

But code within the verifier decides otherwise if the class belongs to the null class loader. verify() calls

    Verifier::is_eligible_for_verification(InstanceKlass* klass, bool should_verify_class) {

which calls

    bool Verifier::should_verify_for(oop class_loader, bool should_verify_class) {
      return (class_loader == nullptr || !should_verify_class) ?
        BytecodeVerificationLocal : BytecodeVerificationRemote;
    }

So returns false for redefining java.lang.VerifyError for example. Should that code be an && above ?

is_eligible_for_verification also has some exceptions, that for redefinition (java.lang.Class etc) should not be exceptions. They should be verified if redefined.

-Xverify:all sets BytecodeVerificationLocal to true, but that's not what's needed for redefinition. There should be a way to call the verifier with an always verify flag.