You have to do that and much more. A "self-hosting" basic OS is a great achievement that I am not trying to downplay. However there really aren't any examples that I am aware of where that was achieved without relying on artifacts somewhere up the chain that come from an external source. I would say that achieving any self-hosting OS without relying on external artifacts is well outside one human lifetime. Edit: You have to completely manually bootstrap your hardware design and manufacturing simultaneously with your software.
