£gC/OS-II is a portable, scalable and preemptive real time kernel. In this paper, we describe the work of porting £gC/OS-II to the Xilinx ML310 platform, which is equipped with a Virtex-II Pro FPGA. Moreover, we also present the accomplishment of an OS4RS (Operating System for Reconfigurable System) prototype by integrating £gC/OS-II with the partial reconfiguration capability of the Virtex-II Pro FPGA. For the porting of the £gC/OS-II, we mainly port the code related to context switch, interrupt, and timer. Moreover, for the OS4RS prototype, we partition the FPGA into four regions and allow different circuits (i.e. hardware tasks) to be dynamically reconfigured (i.e. downloaded) into the regions under the control of £gC/OS-II. Finally, we propose an algorithm to predict and pre-configure the hardware tasks so as to reduce the waiting time of task reconfiguration. According to the simulation results, the proposed algorithm can reduce the waiting time effectively.