paged memory

• processes each see translated memory addresses (can't see physical memory addresses directly)
• only kernel can see untranslated memory addresses directly
• thus in kernelspace we can see specific addresses but in userspace we can't
• kernel "sees" reality
• kernel "sees" itself at beginning of memory space (and thus is at beginning in reality)
• each process "sees" itself as starting at beginning of memory space and "sees" the kernel as being at the end of memory space
• each process may "see" more memory than there actually is, for the following reasons:
  • swap facilitates more space than actually present
  • each process "sees" itself as the only process on the system
• NOTE THAT KERNELSPACE RUNS IN PRIVILEGED MODE

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example