OSDev.org

Hi.
I am currently starting to work on the userspace side of my OS, and I have come to the state where I need a custom toolchain for my OS (so far I've been using the basic x86_64-elf toolchain). The thing is, I know very little about GCC and Binutils and how to customize them.
I tried looking for information, but I only found basic user manuals that explain GCC's options and such. I know that there's a wiki article that explains how to create the toolchain, but I prefer understanding what I'm doing instead of just copying from the wiki (also, I encountered some errors, and it really confuses me).
So, to conclude my little story, I would like to know what docs I should read to better understand GCC and Binutils, and where I can find those docs.
Thanks in advance.