> > What limits user space to 3GB.
> Hardware limitations imposed by the x86 architecture. The x86 only has
> _one_ virtual address space, which has to be shared by user space and
> kernel space. It is not possible to give user space more virtual
> address space without taking it away from the kernel.
You can theoretically run kernel in one task (I mean "task" in the
Intel-processor-meaning of the word ;) ) and userspace programs in another
task, which will result in having 4GB of memory for both of them, won't
it?
I know, there would be big compilcations - for example copying data
betweeen userspace and kernelspace should be problem, and if implemented,
I can't imagine how to do it considerably fast...which is IMHO the main
reason why it isn't done such way.
-- JiKos.
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