A processor device has a cache, and a cache controller that manages the replacement of a number of cache lines in the cache, in accordance with a replacement policy. A storage location is to be configured to define a memory map having a cacheable region, an un-cacheable region, and a real time region. Upon a cache miss of an address that lies in the real time region, the cache controller responds by loading content at the address into a cache line, and then prevents the cache line from aging as would a cache line that is in the cacheable region. Other embodiments are also described and claimed.