Virtual Memory Questions

[Chen Micheal]

1. Why is it not a good idea to save/restore the TLB on context switches
(other than the obvious it increases the context switch time) ?

2. A range of addresses starting at 0x0000000 is intentionally left empty.
Why is this?

[More VM Questions (Segmentation)]

Another question on the review sheet is "how does segmentation improve
address translation? What is the motivation behind segmentation?"

I'm not sure if I have the correct idea:

Basically segmentation allows you to have a separate virtual address space
for different parts of the program (code, data, stack, heap etc.). How is
this useful? As in, how would this improve address translation?