Question about which tools to use, bugs, the best way to implement a function, etc should go here. Don't forget to see if your question is answered in the wiki first! When in doubt post here.
GCC likes to do a bunch of stuff behind the scenes. It's great for application programming because all of the runtime support is already there, unfortunately in OS development you have to make the runtime support yourself. Using that flag tells GCC to not to do some of that stuff behind the scenes, so you don't have to write the stuff until much later where you have an idea as to what you need and how to do it.