On Fri, Oct 12, 2007 at 02:27:52PM +0530, Thippeswamy, Aravind wrote: > I would like to know if the Virtual Memory addressing is > still going to be used in an environment with out any disk/Swap-space. > > The reason I ask this is because, I think that the main point to having > this Virtual memory is to make the processes re-locatable on the RAM and > to support the Demand-Paging concept. If there is no swap-space in the > first place to begin with, is there a need to still have this scheme? Do > all processes + kernel run in Real Mode instead? Real mode and protected mode are specific i386 (or even 80286) concepts, don't use them or otherwise you will confuse things. You probably mean "run without the MMU turned on", or "run with a 1:1 memory mapping". > Or is it that the Protected-mode (with Virtual Memory) is still used but > the mapping from Virtual Address to Physical is more one-to-one? And the > 4 Gb Virtual Address space in any conventional system is not applicable > to this kind of a situation. Swap is only useful for so called anonymous memory, memory that is not backed by a file like all memory you acquire with malloc() calls. Memory that is backed by files (i.e. the binary itself, all libraries, mmap()'ed files) can still be discarded from physical memory if the system needs physical memory for more important things. In order to do that, you still need virtual memory o you can't turn it off when you don't have swap. Erik -- They're all fools. Don't worry. Darwin may be slow, but he'll eventually get them. -- Matthew Lammers in alt.sysadmin.recovery
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