Here's what I think modern geekos development should look like in order to simplify and standardize. This is not what I do, but is the most likely to create a development environment that will definitely work.
Download and install virtualbox from https://www.virtualbox.org or via your package manager (apt-get install virtualbox).
Download and install vagrant from https://www.vagrantup.com.
Download and install git from https://git-scm.com or via your package manager (apt-get install git).
% git clone [the repository]
% cd geekos-project
% vagrant up
(wait a while, or address vagrant's woes about your virtualbox install)
% vagrant ssh
% cd /vagrant/build
% screen make run
Screen is very useful; I would run within screen to make it possible to kill the curses-based qemu using ctrl-a k. To get help, ctrl-a ?, to create a new window, ctrl-a c, to switch windows, ctrl-a a.
I prefer to run qemu with an X window rather than have qemu take over the window using curses. On my linux or mac host, I would instead
% vagrant ssh -- -X
and remove "-curses" from the Makefile.linux.
If you'd prefer to avoid using the custom qemu (probably okay with the possible exception of the scheduler project), remove "-smpQuantum 1000" from build/Makefile.linux