We present a co-simulation environment for multiprocessor architectures, that is based on SystemC and allows a transparent integration of instruction set simulators (ISSs) within the SystemC simulation framework. The integration is based on the well-known concept of bus wrapper, that realizes the interface between the ISS and the simulator. The proposed solution uses an ISS-wrapper interface based on the standard gdb remote debugging interface, and implements two alternative schemes that differ in the amount of communication they require. The two approaches provide different degrees of tradeoff between simulation granularity and speed, and show significant speedup with respect to a micro-architectural, full SystemC simulation of the system description.