在cortex a7上看到PoC和PoU的概念如下：
PoC: the PoC is the point at which all blocks, for example, cores, DSPs, or DMA engines, that canaccess memory are guaranteed to see the same copy of a memory location.
PoU: the PoU for a core is the point at which the instruction and data caches of the core are guaranteed to see the same copy of a memory location.
1.感觉PoC和PoU只是看待内存的主体不一样而已，PoC是具体的agent看同一块内存的数据应该保持一致，而PoU是指的cache L1看同一块内存的数据应该保持一致，这样理解对么？
2.还有就是什么地方会用到PoC和PoU的概念呢？
