"logical" vs "virtual" kernel addresses?

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  i'm trying to understand the distinction (if there *is* one) between
logical and virtual addresses in kernel space.

  according to the LDD3 book, logical addresses are most likely
treated like physical addresses, and might differ from the actual
physical addresses only by a constant offset.  (e.g., logical
addresses in the 3G-4G range might just be reduced by 3G to map into
the first physical 1G of memory, something simple like that.)  in any
case, even with something this simple, there is still a page mapping
operation going on.

  on the other hand, LDD3 describes kernel *virtual* addresses as
"similar" to logical addresses, but possibly without the linear,
one-to-one mapping to physical addresses that logical addresses have.

  so is there a meaningful difference between these two types of
addresses other than a philosophical one?  are they treated any
differently in terms of page mapping?  i'm just curious.

rday

-- 
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Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

http://fsdev.net/wiki/index.php?title=Main_Page
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