> 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.
Why is it that a user process can't intentionally switch segments?
Dereferencing a 32-bit address causes the address to be calculated using the
"current" segment descriptor, right? It seems to me that a process could set
a new segment selector, in which case a dereference would operate on a whole
new segment. Is there a reason why processes are limited to a single
segment?
chris
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This archive was generated by hypermail 2b29 : Sun Oct 15 2000 - 21:00:25 EST