EVM6678 gel文件XMC设置

#define XMPAX2_L     (*(int*)(0x08000000 + 0x00000010))

#define XMPAX2_H     (*(int*)(0x08000000 + 0x00000014))

xmc_setup()

{ 

    /* mapping for ddr emif registers XMPAX*2 */

    XMPAX2_L = 0x100000FF;     /* replacement addr + permission fo segment*/

    XMPAX2_H = 0x2100000B;    /* base addr + seg size (4KB)*/        

}

gel文件中有这样一段代码，replacement addr指向的是36bits的物理地址。那这个0x10000 0000地址应该是物理地址的哪一块？为什么要把0x2100 0000映射过去？