Read/Write Access in Nios II

Thanks for the insight Daixiwen. It brings one more question:

You said :

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I recommend to use the IO_RD/WR macros to access your component, or to use the alt_remap_uncached() routine if you prefer to use pointers. If you don't, the CPU can read data from its cache rather than your components and you'll have strange results.

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How can the CPU read data at the wrong memory location(cache) if the address I store in my pointers specifically target the memory space to which my components are mapped?

In other words, what security these macros/functions bring in terms of addressing?

Thanks