For more than three decades, reverse engineering has been a major issue in industry wanting to capitalise on legacy systems. Lots of companies have developed reverse engineering tools in order to help developers in their work. However, those tools have been focusing on traditional information systems. Working on a time critical embedded system we found that the solutions available focus either on software behaviour structuring or on data extraction from the system. None of them seem to be clearly using both approaches in a complementary way. In this paper, based on our industrial experiment, we list the requirements that such a tool should fulfil. We also present a short overview of existing reverse engineering tools and their features.