Originally Posted by hazzyb
can anyone help me out with the difference among kernel stack and user stack...
Could you say more about what you're trying to figure out?
All I know about the two stacks is that both are required since instructions executed in user-mode should not be able to read or modify the stack used by the kernel. Also, using a separate stack in the kernel might help to make sure the kernel never runs out of stack space.
Good luck, hope this helps!