Messages in this thread | | | Date | Thu, 12 Oct 2000 23:42:07 +0200 (CEST) | From | Ingo Molnar <> | Subject | Re: large memory support for x86 |
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On Thu, 12 Oct 2000, Timur Tabi wrote:
> Of course, you could define a pointer to be a 48-bit value, but I > doubt that would really work.
no, x86 virtual memory is 32 bits - segmentation only provides a way to segment this 4GB virtual memory, but cannot extend it. Under Linux there is 3GB virtual memory available to user-space processes.
this 3GB virtual memory does not have to be mapped to the same physical pages all the time - and this is nothing new. mmap()/munmap()-ing memory dynamically is one way to 'extend' the amount of physical RAM controlled by a single process. I doubt this would be very economical though.
Such big-RAM systems are almost always SMP systems, so eg. a 4-way system can have 4x 3GB processes == 12 GB RAM fully utilized. An 8-way system can utilize up to 24 GB RAM at once, without having to play mmap/munmap 'memory extender' tricks.
Ingo
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