In complex reconfigurable systems on chip, the dynamism of targeted applications requires an efficient management of platforms. To enable run-time resource management, operating system and reconfigurable SoC platform should be developed together. In this context, additionally to the issues inherent to hardware and software design development, we have to deal with the supplementary difficulty of the interaction between software and hardware, and of both with the platform. In this paper we present a real-time debugging tool operating in a mixed hardware and software environment. This dynamically loadable tool seriously decreases the time required for debugging while the overhead in terms of additional code is minimal.