From: james.harris.1@nospicedham.gmail.com   
      
   On 13/04/2019 06:23, Rod Pemberton wrote:   
   > On Thu, 11 Apr 2019 09:39:04 +0100   
   > James Harris  wrote:   
   >   
   >> On 09/04/2019 11:31, Rod Pemberton wrote:   
   >>> On Mon, 8 Apr 2019 13:10:01 +0100   
   >>> James Harris  wrote:   
   >   
   >>>   
   >>> What is the purpose of mapping nothing present address regions as   
   >>> uncacheable? ...   
   >>   
   >> Why map them as cacheable?   
   >   
   > (in questions directly below)   
   >   
   >>>   
   >>> Is there any reason to not cache garbage data?  Anything not cached,   
   >>> including garbage data, will slow down the processor, correct?   
   >>   
   >> It will likely never be read (or written). Accesses to it would   
   >> normally be errors.   
   >   
   > You started this thread asking how to "access addresses which have no   
   > RAM".  If you're accessing many such addresses sequentially, and you   
   > don't know whether the region is or isn't garbage, why would you want   
   > to access them slowly because they're not cached?  You could.   
      
   Not exactly. In the original post I asked   
      
   JH> Does anyone here know what would likely happen to cache   
   JH> lines and buses if one were to read addresses which had   
   JH> no RAM - with or without caching enabled for those   
   JH> addresses?   
      
   I take your point, though, that it should not matter whether addresses   
   which are never accessed are cacheable or not.   
      
      
   --   
   James Harris   
      
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