This paper presents a lightweight service discovery mechanism for the mobile ad hoc pervasive environment, applying cross-layer design to reduce the infrastructure and protocol overhead, and to improve service accessibility. Integrated with the network routing layer, the proposed mechanism automatically identifies the proper service discovery model for the current network configuration. The solution adapts to network expansion with enhanced scalability. Simulation studies of real-time service scenarios employing the proposed mechanism are presented, demonstrating the efficiency of the mechanism and the satisfactory service performance results.