add minimal stdlib.h

Signed-off-by: Boris Figovsky <borfig@gmail.com>
fix outs* buffer register

Signed-off-by: Boris Figovsky <borfig@gmail.com>
mem: refactor kernel virtual memory allocation

Signed-off-by: Boris Figovsky <borfig@gmail.com>
Introduce generic file interface

Signed-off-by: Boris Figovsky <borfig@gmail.com>
Add some values from BIOS Data Area

Signed-off-by: Boris Figovsky <borfig@gmail.com>
initial (and blocking) implementation of serial port

Signed-off-by: Boris Figovsky <borfig@gmail.com>