Why linux kernel use trap gate to handle divide_error exception?

Question

In kernel 2.6.11.5, divide zero exception handler is set up as:

set_trap_gate(0,÷_error);

According to \"Understanding The Linux

Answer 1

The kernel is not running under user mode. It has to handle the trap generated by user mode programs (e.g. linux processes in user-land). Kernel code is not expected to divide by zero.

I don't understand well your question. How would you implement it otherwise?