Is it possible to turn off the gcc optimization when compiling kernel?

[Hao Lee]

Hi,
When I am debugging the linux kernel, I find that the execution
sequence of some code is very strange. I think I need to turn off gcc
optimization by  changing "-O2" to "-O0". But I encounter many errors.
So, I want to know is it possible to turn off the gcc optimization or
how can I compile some functions without optimization.
Thanks.