Hi
I have basic questions about gates.

Intel designed gates for system calls.
Why?
Because:

" * Note that both the selector and offset are given in the call gate
preventing lower privileged programs from jumping into the middle of higher
privileged code.
o This mechanism makes the higher privileged code invisible to the
caller.

* Call Gates have "tolls" as well, making some or all of them
inaccessible to lower privileged processes.
o The rule is that the Call Gate's DPL field (bits 45-46) MUST be
1-) Why does higher privileged code need to be invisible?
2-) Are there only 2 reasons(above) to design "gates"? Do I miss something?

Thanks...