The recent advancement of embedded devices is requiring excellent performance of processors, so the use of multi-core processor is increasing as its solution. To achieve high performance in multi-core, data is being processed by using shared memory with highest performance among IPC methods. In the case of a system using single bus, it uses memory with same shared memory for each processor core. Accordingly, it is possible to use shared memory method between processors only by modifying the data structure of OS. However, in the case of using separate bus for each processor to high performance, physical memory address used in process is different and unless a special method is used, so it does not provide data sharing method between processors.

To support shared memory in dual bus environment for each processor, memory controller that allows communication with bus connected to two processors was added. Through this controller, two processors end up having new memory area that can be accessed by both processors, and it is possible to read or write data to this address. In the case of using this memory area, most processors transmit data to different areas. Accordingly, interrupt was used in the case of recording data by creating shared memory from a particular processor to be made aware by processor that intends to read data.

For various processors to use the memory connected to memory controller, it was divided into the unit of logical segments with 4KByte in size of one segment. Memory used by memory controller is SRAM, and 4Byte register of inside process was used for the setting of whether particular memory area is being used. This register consists of 2 status bit indicating whether corresponding segment is being used and 1 direction bit indicating the information of processor currently assigned with segment. Accordingly, corresponding memory segment is being used is identified through the set-up value of this register, and the value of this register is changed with new assigned segment.

In terms of the shared memory used in this paper, list data structure was used to manage segment through which it was designed to manage segment information. Since maximum segment of shared memory is limited to 8, it used the method of removing segment with the lowest frequency of usage from data structure upon using LFU algorithm in where usable segment no longer exists.

To test the shared memory designed in this paper, it was performed in AMP method embedded Linux OS for which it was designed in shared memory controller device driver. For AMP multi-core test, Linux OS was installed in 2 processor cores.

Through the set-up of DDR and NAND memory partition used in Linux kernel, it verified that Linux OS is simultaneously executed. In addition, it verified the creation and use of shared memory by using device driver implemented to test shared memory.