How to config DSP Cache?

Hi 

   I am config DSP cache, for example:

Cache = xdc.useModule('ti.sysbios.family.c64p.Cache');
Cache.MAR128_159 = 0x0000ffff; /* the external memory range (0x80000000-0x8FFFFFFF) cacheable */
//Cache.MAR192_223 = 0x00000008; /* xxxx xxxx xxxx xxxx xxxx xxxx xxxx 10xx */

I don't known what about this. 

Is there some document? What's mean about this?

Thanks